ASTM D5302 Standard Test Method for Evaluation of Automotive Engine Oils for Inhibition of Deposit Formation and Wear in a Spark-Ignition Internal Combustion Engine Fueled with Gasoline and Operated Under Low-Temperature, Light-Duty Conditions
6.1 General Description:
6.1.1 The test engine is a 2.3-L, spark ignition, four-stroke, four-cylinder in-line engine. Features of this engine include an overhead camshaft, a cross-flow fast-burn cylinder head design, and electronic port fuel ignition. It is based on the Ford Motor Company's 2.3-L EFI Ranger truck engine.
6.1.2 Use an engine test stand equipped to control engine speed and load, air-fuel ratio, various temperatures, and other parameters.
6.1.3 Use appropriate air conditioning apparatus to control the temperature and humidity of the intake air.
6.1.4 Use an appropriate fuel supply system.
7. The Test Engine
7.1 Sequence VE Test Engine Parts Kit - The kit is available from the Ford Motor Company and contains all the necessary consumable hardware for four tests. Tests starting after May 31, 1995, shall use 1992 or later test engine parts kits with the dual plug cylinder head. A complete list of parts included in the kit is shown in Table A4.1.
7.1.1 The following required parts are to be obtained from the kit (unless substitutions for those parts are specifically approved by the Sequence VE Operations and Hardware Subpanel (contact the ASTM Test Monitoring Center (TMC) for guidance): cylinder block, cylinder head, pistons, piston rings, camshaft, rocker arms, and connecting-rod bearings.
188.8.131.52 Tests started on or after November 16, 1999 may use substitute non-kit parts (other than those listed in 7.1.1) obtained from Ford dealers, provided that the part numbers are the same as those in the kit. Where parts substitutions are made, maintain samples of the substituted part for possible comparison. Identify all substituted parts with the part numbers on the Supplemental Operational Data Form of the test report (Fig.A7.5). Cordinate the use of substituted parts with the TMC.
7.1.2 Premeasured and calibrated Sequence VE engine parts are available from the supplier listed in X2.1.5.
7.2 Required New Engine Parts - Install the following new parts in each new test engine assembly: cylinder head (may be reused for tests starting on or before May 20, 1999) cylinder head bolts (torque-to-yield), camshaft, camshaft bearings, camshaft drive belt, rocker arms, hydraulic lifters, intake and exhaust valves, valve stem seals, pistons, piston rings, wrist pins, connecting-rod bearings, main bearings, oil pump, oil filter, PCV valve, spark plugs, and gaskets and seals.
7.3 Reusable Engine Parts - The following parts can be reused: cylinder block (can be used for approximately two tests, depending on bore wear); valve springs (can be reused as long as they meet the specifications detailed in Annex A3); cylinder heads (for tests started on or after May 20, 1999, provided an acceptable reference oil test, incorporating reused cylinder heads and meeting the requirements in Annex A16, has been completed); auxiliary shaft and bearings, connecting rod, front seal housing, fuel management wiring harness, crankshaft ignition trigger, intake manifold, throttle body, camshaft drive parts, water pump drive parts, crankshaft, fuel injectors, ignition module, ignition wires, oil pump screen and pick up tube, timing belt sprockets, and water pump (all of these can be used in numerous engine assemblies as long as they remain serviceable).
7.4 Specially Fabricated Engine Parts - The following subsections detail the specially fabricated engine parts required in this test method:
7.4.1 Intake Air Horn (see Fig. 1 and Fig. A3.4):
7.4.2 Camshaft Baffle (see Fig. A3.24) - This is fabricated for attachment to the cam bearing pedestals. The clearance between the edges of the baffle and the rocker arm cover (RAC) permits a limited splash flow of oil to the top of the baffle and the RAC. Therefore, the dimensional accuracy of the baffle is important to minimize the influence on test severity. The camshaft baffle is available from the supplier listed in X2.1.13.
7.4.3 Crankcase Oil Fill Tube (see Fig. A3.27) - This design is not a requirement, but if an alternative part is used, install a suitable shut-off valve between the fill tube and the engine.
7.4.4 Dipstick Tube - Replace the existing dipstick tube with a 1/8 -in. NPT pipe nipple. The nipple should be approximately 6-in. (150-mm) long and is threaded into the port on the left side of the crankcase, as shown in Fig.A3.13.
7.4.5 Dipstick - Use the special dipstick shown in Fig.A3.28 to measure the oil level in the modified oil pan.
7.4.6 Oil Pan - Obtain the special oil pan shown in Fig.A3.25 from the supplier listed in X2.1.13.
7.4.7 Flywheel Timing Indicator - Fabricate a bracket with an adjustable timing index pointer for use at the flywheel. Mark the flywheel with graduations at top dead center (TDC) and from 26 to 30° in 1° increments before top dead center (BTDC) and after top dead center (ATDC). The suggested mounting location is between two of the flywheel housing bolts on the upper left side of the crankcase. Since ignition timing is measured with an accuracy of 1°, configure the index pointer to minimize parallax error.
7.4.8 Rocker Arm Cover - The RAC is fabricated from stainless steel and incorporates a water jacket. The RAC supplier is listed in X2.1.13.
7.5 Special Engine Measurement and Assembly Equipment - Items routinely used in the laboratory and workshop are not included.
7.5.1 Camshaft and Rocker Arm Hardness Tester and Fixtures - Use a hardness tester to measure the camshaft lobe and rocker arm hardness in the range from 50 to 60 HRC (Hardness - Rockwell C). The tester and fixtures shall allow accurate and repeatable results at the specified locations on these parts (see 184.108.40.206 and 7.8.7).
NOTE 1 - Repeatable hardness measurements are difficult to achieve without properly designed fixtures.
7.5.2 Camshaft Lobe Measurement Equipment - A snap gage dial indicator is recommended for measurement of camshaft lobe heel-to-toe distance.
7.5.3 Camshaft Lobe Orifice Flow Rate Device:
220.127.116.11 Determine camshaft lobe orifice plugging with the device detailed in Fig.A3.32. The device measures restriction of air flow relative to a clean lobe by means of a probe placed in the external opening to each lobe orifice. The device shall be capable of controlling static air pressure at 10.0 in. water (2.49 kPa).
18.104.22.168 Calibrate the flowmeter with a reference (clean) cam lobe each time a camshaft is rated for plugging. Since the measurement is a relative flow rate reduction, repeatability, rather than absolute accuracy, is the primary concern (see Fig.A3.32 and 13.4.4).
7.5.4 Rocker Arm and Connecting-Rod Bearing Weighing Equipment - A precision weight scale with an accuracy of 0.25 % and a resolution of 0.1 mg is necessary. Rocker arm weights are approximately 105 g, while individual bearing insert weights are approximately 20 g.
7.5.5 Unassembled Valve Spring Calibration Device - Use this device to screen valve springs before assembly in the cylinder head (see 22.214.171.124). The spring loading is measured at a compressed height of 1.16 in. (29.5 mm). The tester shall have an accuracy of 2 % and a resolution of 1 lbf (4.45 N).
7.5.6 Assembled Valve Spring Calibration Device:
126.96.36.199 This device is used to measure valve spring loading after the springs have been assembled in the cylinder head. Use the procedure specified in 188.8.131.52 in conjunction with the device. A suitable fixture may be purchased from the supplier detailed in X2.1.13 and X2.1.5.
184.108.40.206 Calibrate the valve spring force measurement device at least once every three months. The calibration technique is left to the discretion of the testing laboratory.
7.5.7 Valve Stem and Guide Measurement Equipment - Any of the following methods is acceptable for measuring valve stem-to-guide clearance (see 220.127.116.11). One method is specified in Footnote 14 utilizing a special tool. Other commercially available automotive service equipment can also be utilized. Alternatively, air gaging equipment can be used to measure the guide diameter, and a micrometer can be used to measure the valve stem diameter.
NOTE 2 - Accurate measurement of stem-to-guide clearance is important since this parameter can affect oil consumption.
7.5.8 Connecting-Rod Heater - The piston pins are fixed to the connecting-rods with an interference fit. A connecting-rod heater is required to facilitate the installation of the piston pins and prevent piston distortion (see 7.8.13). This type of heater minimizes the heat exposure of the rods and consequently minimizes the safety hazard to personnel.
7.5.9 Cylinder Block Stress Plates - Install two stress plates on the cylinder block during honing and measurement operations to minimize cylinder bore out-of-round and taper. Fabricate one plate in accordance with the details shown in Fig.A3.36. The second stress plate can be purchased from the supplier detailed in X2.1.28. Install the thinner of the two plates on top.
7.5.10 Cylinder Block Honing Machine - Use a Sunnen CK-10 or CV-616 honing machine for cylinder bore resizing and finishing. The Sunnen honing lubricant or Mobil VAC-MUL 3-D lubricant, a 30-tooth ratchet, and EHU-525 and JHU-625 (or JHU-820) honing stones are required in this application. See Table 1.
7.5.11 Cylinder Bore Surface Finish Analyzer:
18.104.22.168 The analyzer is required to measure the cylinder bore surface finish after completion of the honing operation. The range of the analyzer shall cover a minimum from 8 to 20 µin. (0.0002 to 0.0005 mm). An instrument with a mechanically driven profilometer stylus is recommended since repeatable measurements are difficult to achieve with a hand-held instrument.
22.214.171.124 Calibrate the surface finish analyzer with a commercially recognized surface finish calibration standard. The frequency of calibration shall comply with the manufacturer's specification for the particular analyzer used.
7.5.12 Cylinder Bore Measurement Ladder - The bore measurement ladder is required to ensure precise location of the cylinder bore measurement at the top, middle, and bottom of the piston ring travel. Fabricate the bore ladder in accordance with the details shown in Fig.A3.38.
7.5.13 Piston Ring Positioner - Use the piston ring positioner to locate the piston rings 2.0 in. (51 mm) from the upper surface of the stress plate. This allows the compression rings to be positioned in a standard location in the cylinder bore before measurement. Fabricate the positioner in accordance with the details shown in Fig.A3.37.
7.5.14 Piston Ring Grinder - A precision ring grinder is required for adjusting ring gaps before assembly. A suitable ring grinder is available from the supplier shown in X2.1.21.
7.5.15 Oil Pump Calibration Device:
126.96.36.199 Calibrate the engine oil pump by precisely adjusting the pressure relief valve, utilizing a calibration device similar to the one detailed in Fig.A3.30 and Fig.A3.31. The device drives the pump at a constant speed and circulates Mobil EF-411 oil, while the oil temperature and flow rate are controlled. The pump discharge pressure is adjusted by means of the pressure reliefvalve. The oil flow rate sensor and readout shall have an accuracy of 2 % of full scale and a resolution of 0.1 gpm. The pressure measurement system shall have an accuracy of 1.0 % of full scale and a resolution of 0.5 psig (3.4 kPa).
188.8.131.52 Calibrate the oil pump calibration device at least once every three months. The calibration technique is left to the discretion of the testing laboratory.
7.5.16 PCV Valve Flow Rate Device:
184.108.40.206 Use this device to verify the flow rate of the PCV valves before the test and to measure the degree of clogging after the test is completed. Fabricate the device in accordance with the details shown in Fig.A3.34. The device shall have an accuracy of 5 % of full scale and a resolution of 0.1 cfm (0.047 L/s) (see 7.6.9).
220.127.116.11 Calibrate the flow rate device once every six months against a standard traceable to national standards. Perform calibration checks biweekly, or more frequently with modified PCV housings that contain fixed orifices (see Fig.A3.35).
7.5.17 Probe for Engine Timing Calibration - Use the cylinder probe to calibrate the crankshaft pulley and the flywheel at TDC of the Number 1 piston.
7.5.18 Engine Service Tools - A complete list of special tools for the test engine is shown in Annex A1. The tools are available from a Ford dealer or from the supplier listed in X2.1.27. These are designed to aid in performing several service items, in addition to the following specific service items that require special tools to perform the functions indicated (if not self-explanatory):
18.104.22.168 Camshaft Belt Tension Adjusting Tool, (Part No. T74P-6254-A).
22.214.171.124 Valve Spring Compressor Lever, necessary for rocker arm installation. (Part No. T74P-6565-A.)
126.96.36.199 Engine Plug Replacer, necessary for freeze plug installation. (Part No. T74P-6015-A.)
188.8.131.52 Camshaft and Auxiliary Shaft Seal Replacer, (Part No. T74P-6150-A).
184.108.40.206 Fuel Injector Test Rig - A suitable device capable of accurate, repeatable flow measurement of port fuel injectors is required. This device shall be capable of performing necessary port fuel injector evaluations, as outlined in 7.6.11. Since no suitable commercially available apparatus has been identified, design of the test rig is left up to the laboratory.
7.6 Miscellaneous Engine Components - Preparation:
7.6.1 Engine Buildup and Measurement Area-Environment - The ambient atmosphere of the engine buildup
and measurement areas shall be reasonably free of contaminants. A relatively constant temperature (within +/- 3°C) is necessary to ensure acceptable repeatability in the measurement of parts dimensions. The relative humidity should be maintained at less than 75 % to prevent moisture forming on cold engine parts that are brought into the buildup or measurement areas.
7.6.2 Oil Pump:
220.127.116.11 Calibrate the oil pump to help provide uniform oil flow rates from test-to-test. The oil pump is calibrated with an oil pump calibration device (see Figs.A3.30 and A3.31, and 18.104.22.168). The oil pump relief adjuster assembly replaces the blanking plug and is used to position the relief valve spring during calibration and operation (see Fig.A3.29).
22.214.171.124 The oil pressure relief valve assembly is located behind the blanking plug. The plug is difficult to remove, and it may be necessary to apply heat to the oil pump casing to break down the thread locking adhesive. After the blanking plug has been removed, install the adjuster assembly.
126.96.36.199 Mount the oil pump on the calibration device. Fill the calibration device with EF-411 oil and circulate and heat the oil until it reaches 125 +/- 5°F (51.7 +/- 2.8°C). Adjust the oil pump speed to 1250 +/- 10 rpm (130 +/- 1 rad/s), and set the flow rate at 6.6 +/- 0.1 gal/min (0.420 +/- 0.006 L/s). Adjust the relief valve spring tension until the pump output pressure registers 60 +/- 1 psig (414 +/- 7 kPa).
188.8.131.52 If oil pressure fluctuations are observed during calibration, disassemble the relief valve and correct the problem. Significant air entrainment in the oil in the calibration device indicates unacceptable leakage on the suction side of the pump.
7.6.3 Oil Pump Pickup Tube and Screen - Clean the oil pickup tube and screen assembly, and inspect the assembly for defects.
7.6.4 Throttle Body:
184.108.40.206 The required throttle body modifications are detailed in Fig.A3.19. Remove all tubes and plug the holes with pipe plugs and a suitable thread sealer. Remove and discard the outer and inner throttle body shaft seals. Use of the throttle position sensor and the multiplier linkage is optional.
220.127.116.11 Disassemble and thoroughly clean the throttle body before each test. Remove the butterfly from the throttle shaft, and remove the shaft from the throttle body. Discard the rubber throttle body shaft seals, and soak all parts in a commercially available carburetor cleaner. After the parts have been thoroughly cleaned and air-dried, install new throttle body shaft seals. The seals should be lightly lubricated on all surfaces with EF-411 oil to facilitate installation. Do not use any other lubricant on the seals. Reassemble the throttle body.
18.104.22.168 There is no specific life for the throttle body. However, the clearance between the bore and the butterfly will eventually increase and render the body unserviceable. When the clearance becomes too great to allow control of speed, load, and air-fuel ratio during Stage 3, discard the throttle body.
7.6.5 Intake Manifold:
22.214.171.124 The intake manifold is comprised of three parts: upper intake manifold, lower intake manifold, and intake manifold spacer. The spacer is necessary to allow the upper intake manifold to clear the RAC (see Fig.A3.20). The spacer can be purchased separately or as part of a kit of modified parts available from the supplier detailed in X2.1.13. Modify the intake manifold, as detailed in Fig.A3.21. Block the EGR valve port by means of a cover plate or pipe plug. Locate the PCV valve vacuum connection at the lower port on the upper intake manifold, as detailed in Fig.A3.21. Locate the intake manifold vacuum measurement, fuel pressure regulator, and manifold absolute pressure (MAP) sensor connections at the upper port on the upper intake manifold, as detailed in Fig.A3.21.
126.96.36.199 Disassemble and thoroughly clean the intake manifold before each test by soaking in a commercially available carburetor cleaner. This is followed by a hot (> 60°C) water rinse and forced air-drying. The intake manifold can be used in repeated builds.
7.6.6 Rocker Arm Cover:
188.8.131.52 Before each test, flush the RAC coolant jacket with a mixture of hot (> 60°C) water and tri-sodium phosphate detergent. After flushing, inspect the coolant jacket. If a deposit or film is present, clean the RAC coolant jacket with a commercially available de-scaling cleaner, neutralizer, and inhibitor (see 184.108.40.206). Examples of acceptable cleaners are detailed in 7.7.
220.127.116.11 Inspect the appearance of the interior surface of the RAC. If the before test rating is less than ten on the CRC varnish rating scale (Manual 14), polish the interior surface lightly with Number 0 fine steel wool to achieve a fine dull shine. Rinse the cover with aliphatic naphtha and allow to air-dry before use.
7.6.7 Camshaft Baffle - Polish the camshaft baffle with Number 0 fine steel wool to achieve a fine finish. Rinse with aliphatic naphtha and allow to air-dry before use.
7.6.8 Oil Pan - Inspect the appearance of the tin plating on the internal surface of the pan. Polish lightly with Number 0 fine steel wool to achieve a dull shine. Rinse with aliphatic naphtha and allow to air-dry before use. Replate the pan when the finish becomes unserviceable (see 7.4.6).
7.6.9 PCV Valve - Measure and record the flow rates of the PCV valves with the calibrated flow device described in 7.5.16 and Fig.A3.34. Measure the flow rate at 8 and 18-in. Hg (27 and 61-kPa) vacuum. Because of the hysteresis in the PCV valve spring, make the vacuum adjustments in one direction only. Measure the flow rate twice and average the readings. Reject any PCV valve that does not exhibit an average flow rate between 2.40 and 2.90 cfm (1.13 and 1.37 L/s) at 8 and 18-in. Hg vacuum.
7.6.10 Water Pump Drive System - Use only the pulleys provided in the Sequence VE Test Stand Set-Up Kit (see Table A4.2) to ensure that the water pump rotates at the proper speed.
7.6.11 Fuel Injectors:
18.104.22.168 Prior to engine installation, evaluate all injectors (new and used) for spray pattern and flow rate using a suitable apparatus as identified in 22.214.171.124. The evaluation procedure is outlined in this section. Injectors may be cleaned and reused if the criteria outlined in this section are satisfied.
126.96.36.199 Flush new injectors for 30 s to remove any assembly residue before flow testing.
188.8.131.52 Using a rig as described in 184.108.40.206, place the injector(s) in the rig and turn on the pressure source. After the pressure source is turned on, the test fluid (see 7.7.1) will start to flow through the injector(s). Maintain the test fluid pressure supplied to the injector(s) at 39 +/- 0.5 psi (269 +/- 3.4 kPa) during the entire test. The maintenance of this pressure is critical because a small change in pressure will have a dramatic effect on the flow rate and spray pattern. Once pressure is set, zero the volume measuring device.
220.127.116.11 Apply pressure to the closed injector(s) for at least 30 s. The injector(s) shall not leak or drip. Replace any injector that leaks or drips.
18.104.22.168 Flow-test each injector for a 60-s period. While the injector is flowing, make a visual observation of the spray pattern quality. The spray pattern should be typical for the make and model of the injector.
22.214.171.124 The total flow for each injector after the 60 s test shall be between 3.7 oz (109 cm3) and 4.5 oz (134 cm3) at 39 +/- 0.5 psi (269 +/- 3.4 kPa) of test fluid pressure. Discard any injector that flows above or below this range.
7.7 Solvents and Cleaners Required - No substitutions for the following are allowed: (Warning - Use adequate safety provisions with all solvents and cleaners.)
7.7.1 Aliphatic Naphtha, Stoddard solvent or equivalent is satisfactory.
7.7.2 Ethyl Acetate.
7.7.3 Organic Solvent, Penmul L460 18 or Oakite 811.
126.96.36.199 Implement the specified gas chromatographic monitoring program (see Annex A10) when using Oakite 811 to prevent gelatinous-type coatings on water-rinsed parts.
7.7.5 Tri-Sodium Phosphate Detergent, cylinder block and RAC cleaning detergent.
7.7.6 Formulation No. 7 Cooling System Cleaner - Heavy-Duty, cooling system flushing agent to engine cooling system cleanser consists of the following:
188.8.131.52 Oxalic Acid Dihydrate Tech.
184.108.40.206 Alkylated Naphthalene, Sodium Salt - Petro Dispersant 425 (soap).
220.127.116.11 Soda Ash Light - (Neutralization).
7.7.7 Dearsol134 Acidic Cleanerwith Inhibitor, (or equivalent). RAC cooling system cleaner.
7.7.8 Commercial solvent, designated for cleaning carburetors.
7.8 Assembling the Test Engine - Preparations - Functions that are to be performed in a specific manner or at a specific time in the assembly process are noted. Any assembly instructions not detailed as follows should be completed in accordance with the instructions in Footnote 14.
7.8.1 Parts Selection - Instructions concerning the use of new or used parts are detailed in 7.1.1, 7.2, and 7.3.
7.8.2 Engine Measurement Records - Record the engine measurements on data sheets equivalent to those shown in Appendix X1.
7.8.3 Buildup Lubrication - Lubricate all engine parts with EF-411 oil during assembly.
7.8.4 Sealing Compounds - No specific compounds required.
NOTE 3 - Silicone-based sealers should be used with care since they can elevate the indicated silicon content of the used oil. Also use tape sealers with care because tape fragments can plug oil orifices in the oiling system.
7.8.5 Gaskets and Seals - Use new gaskets and seals at all locations during each engine assembly.
7.8.6 Cylinder Head:
18.104.22.168 Cleaning - Rifle-brush cylinder head guides with a valve guide brush and aliphatic naphtha. Remove the end plugs of the camshaft and rifle-brush the central gallery with a valve guide brush and aliphatic naphtha. Rinse with aliphatic naphtha and air-dry with compressed air. Reinstall the camshaft end plugs after the air-drying.
22.214.171.124 Valve Guides - Measure and record the valve stem-to-guide clearance for each valve (see 7.5.7). The clearances shall be within the following specifications: exhaust at 0.0019 to 0.0032 in. (0.048 to 0.081 mm) and intake at 0.0014 to 0.0027 in. (0.036 to 0.069 mm). The clearances can be adjusted by selectively fitting valves or reaming the valve guides.
126.96.36.199 Camshaft Bearings - Inspect the bearings for any anomalies and ensure the bearing holes are properly aligned with the oil gallery in the Number 2 and 3 pedestals. Tap the 0.237-in. (6.02-mm) holes in the top of the pedestals to receive the cam baffle hold-down bolts (see Fig. A3.24). While Fig.A3.24 shows that 5/16 -in. (8–mm) machine screws are satisfactory for this purpose, experience has shown that 7-mm machine screws may be a preferred alternative.
188.8.131.52 Camshaft: Install 1992 VF kit cams, part no. E59E-6251-DA, serial numbers 920160 through 922882 (available October 31, 1993) for all reference oil tests and associated non-reference oil tests starting on or after October 1, 1994.
(a) Lobe Height and Lift Measurement - Measure and record the heel-to-toe dimension of each camshaft lobe at the maximum lift point and at a plane perpendicular to the maximum lift point. Subtract the value taken perpendicular to the maximum lift point from the heal-to-toe value. This difference is the camshaft lift. Reject any cam that exhibits a lift value that does not fall between 0.2367 and 0.2391 in. (6.012 and 6.073 mm). Note that the before test heal-to-toe dimension is also used as the baseline measurement for determining wear (see 13.6.1). Record the actual values for both measurements in the appropriate spaces of the form in Fig.X1.3.
(b) Lobe Hardness Measurement - Measure and record the lobe hardness 180° from the maximum lift point and approximately 0.05 in. (1.3 mm) from the forward edge of each lobe. Include the individual cam lobe hardness measurements on the hardness measurement data sheet (see Fig.X1.4).
(c) Oil Groove Measurements - Measure and record the oil groove depth and width on the Number 2 and 3 journals. Calculate the nominal depth and width using the following equations:
nominal groove depth = (G + D)/2
G = maximum groove depth, and
D = minimum groove depth.
nominal groove width = (E + R)/2
E = maximum groove width, and
R = minimum groove width.
The nominal oil groove depth shall be between 0.039 and 0.047 in. (0.99 and 1.19 mm), and the nominal oil groove width shall be between 0.052 and 0.063 in. (1.32 and 1.60 mm). The grooves can be machined to bring the dimensions within the specifications. Reject any camshaft that cannot be modified to achieve these specifications.
184.108.40.206 Lobe Hole Measurements - Measure and record the lobe hole diameter on each lobe. The lobe hole diameters shall be between 0.047 and 0.055 in. (1.19 and 1.40 mm). The holes can be drilled to bring the diameters within the specification. Reject any camshaft that cannot be modified to achieve this specification.
220.127.116.11 Journal Through-Hole Measurements - Measure and record the journal through-hole diameter of the Number 2 and 3 journals. The journal through-holes shall be between 0.116 and 0.124 in. (2.95 and 3.15 mm). The holes can be drilled to bring the diameters within the specification. Reject any camshaft that cannot be modified to achieve this specification.
NOTE 4 - The axis of the journal through-hole is not perpendicular to the centerline of the camshaft.
7.8.7 Rocker Arms - Clean each rocker arm with ethyl acetate and allow the rocker arm to air-dry before taking any measurements. Measure and record the hardness and weight of each rocker arm. The hardness is measured on the cam lobe mating surface toward the fulcrum end of the rocker arm. The measurement shall be within 0.100 in. (2.5 mm) of the edge of the camshaft mating surface and near the centerline of the rocker arm. Reject any rocker arm that exhibits a hardness less than 57 HRC. A special holding fixture for the rocker arm is required for hardness measurements (see 7.5.1).
7.8.8 Valve Springs:
18.104.22.168 Free Length - The valve spring free length should be between 1.9 and 2.0 in. (48.3 to 50.8 mm).
22.214.171.124 Out-of-Square - The valve spring out-of-squareness should be 0.075 in. (1.91 mm) maximum.
126.96.36.199 Load - If the springs are within the free length and out-of-square specifications, then measure the load in the unassembled valve spring calibration device (see 7.5.5). This should be 167 +/- 8 lbf at 1.16 +/- 0.03-in. (740 +/- 20 N at 29.5 +/- 0.8-mm) deflection.
188.8.131.52 Installation - Lubricate each valve seal and valve stem with EF-411 oil. Install the valve seal over the end of the valve stem with a plastic installation cap in place. Carefully seat the seals fully on the guides. Install prescreened valve springs and retainers. When installing the valve springs and retainers, do not compress the springs excessively. Excessive spring compression can damage the valve seals. Measure and record the assembled height of the valve springs in accordance with the procedure described in Footnote 15. The assembled height shall be between 1.53 and 1.59 in. (38.8 and 40.4 mm).
(a) Check calibration of fixture load cell. Verify within procedure limits. Make calibration adjustments as required to achieve + 0.4 lb (+ 1.8 N) accuracy.
(b) Check head support fixture for correct setup for the VE cylinder head.
(c) Place VE cylinder head in holding fixture with intake valve springs accessible.
(d) Position air cylinder/load cell to allow compressing intake valve spring No. 1 (far left).
(e) Position dial indicator with plunger on rocker cover gasket rail (see Fig.A3.47).
(f) With zero air pressure to air cylinder, position the dial indicator to achieve exactly 0.100-in. (2.54-mm) deflection preload against the rocker cover rail. This allows determination of positive or negative displacement of the valve.
(g) Actuate the air cylinder in a rapid consistent manner to compress the intake valve spring.
(h) Adjust air regulator to achieve exactly 0.400-in. (10.16-mm) valve spring compression. This is indicated as 0.500 in. (12.70 mm) on the dial indicator.
(i) Discharge the air cylinder in a consistent manner and allow intake valve to close to the fully seated position. The dial indicator should read 0.100 in. (2.54 mm) (zero valve displacement).
(j) If the dial indicator did not accurately repeat
0.100 + 0.001-in. (2.54 + 0.02-mm) reading, conduct steps (f) through (i) and adjust the dial indicator as necessary to achieve accurate repeatability of indicated seated and displaced valve positions (0.100 in. and 0.500 in.).
(k) If the dial indicator accurately repeated the desired value, actuate and discharge the air cylinder three additional times and verify repeatability of the indicated valve positions.
(l) Open air valve to compress valve spring to the displaced position.
(m) Record indicated force (lb).
(n) Position air cylinder/load cell to check remaining three intake valve springs. Conduct steps (e) through (m) for each remaining intake valve spring.
(o) Position cylinder head in fixture with exhaust valve springs accessible. Conduct steps (e) through (m) for each exhaust valve spring.
(p) Replace any springs requiring applied force less than 159 lb (707 N) or more than 175 lb (778.4 N). Recheck spring calibration and record compressed force of any replaced springs (see steps d through m).
7.8.9 Short (Cylinder) Block - Use the 1992 VF cylinder block (1992 VF cylinder block, part number F37E-6010-AB, is available for use October 31, 1993) for all reference oil tests and associated non-reference oil tests starting on or after October 1, 1994.
184.108.40.206 Initial Preparation—Disassemble the short block and remove all gallery plugs and freeze plugs. Reinstall the main bearing caps and torque them to 85 +/- 5 lbf·ft (115 +/- 7 N·m). Inspect the coolant jacket to ensure the coolant passages are reasonably free of casting slag. Remove the external oil separator on the left side of the crankcase. Plug the hole with a 1/2 -in. NPT pipe plug. Remove the internal sheet metal baffle located inside the block, underneath the oil separator passage. Tap the dipstick tube hole to accept a 1/8 -in. NPT pipe nipple (see 7.4.4). Tap the monolithic timing port to accept a 3/8 -in. NPT pipe (see 7.4.3).
220.127.116.11 Cleaning - Submerge the cylinder block in agitated organic solvent (see 7.7.3) until clean (approximately 1 h). Rinse the parts thoroughly with hot water (> 60°C). Spray rinse with aliphatic naphtha and use compressed air to force air-drying. Ifthe cylinder block is going to sit idle for an excessive period of time before honing, spray all parts with aliphatic naphtha containing 10 % EF-411 oil by volume. Perform final cylinder block cleaning and preparation after the block is honed and the pistons and rings are fitted.
(a) Install a used head gasket between the block and the stress plate. Install the stress plates (see 7.5.9), main bearing caps, and water pump for honing and measurement of the cylinder bores and ring gaps. Use torque-to-yield bolts when installing the stress plates. Torque the head bolts in accordance with the sequence described in Footnote 14 in two stages, 55 +/- 5 lbf·ft (75 +/- 7 N·m) and an additional 90 to 100° clockwise rotation.
(b) Install the block in a honing machine. (Sunnen CK-10 or CV-616 honing machines have been found suitable. However, any honing machine capable of producing the desired cross-hatch pattern and cylinder microfinish can be used.) The appropriate Sunnen honing machine setups and honing stone selections are shown in Table 1. These speeds and stroke rates provide a cross-hatch pattern with a 30 or 40° maximum included angle. The selection of stones is optional as shown in Table 1.
(c) Experience has shown that two complete strokes with the rough stones are required to break up the bore glaze and prevent the finer stones from loading up with debris. Ten to fifteen strokes are required to obtain the desired cylinder microfinish. The honing lubricant shall not contain any excessive amount of honing debris.
(d) If the cylinder block has been used in a previous test, make sure all worn areas are eliminated during honing. If any worn areas are still present after honing, re-hone the cylinder block to the next larger size or discard the cylinder block.
18.104.22.168 Surface Finish - Measure the finish of each cylinder bore using a 0.030-in. (0.76-mm) cutoff on the profilometer. Record the typical finish measured at the top, middle, and bottom elevations of the bores. Calibrate the profilometer frequently.
22.214.171.124 Bore Measurements:
(a) Measure the cylinder bores with the stress plate and the main bearing caps in place. Clean the bores with a dry rag until no further residue appears after wiping. The bores shall be clean and dry when they are measured. Use the bore ladder (see Fig.A3.38) and a bore gage micrometer to determine the diameter of each cylinder at the top, middle, and bottom of second compression ring travel in both the longitudinal and transverse directions.
(b) Record the bore diameters in 0.0001-in. increments over 3.7800 in. (0.003 mm over 96.010 mm). The cylinder bore out-of-roundness represents the difference between the longitudinal and transverse diameters. Calculate and record the out-of-round value for each second ring travel location. This value shall not exceed 0.0010 in. (0.025 mm) at any location.
(c) Calculate and record the cylinder bore taper value for each cylinder: this represents the difference between the largest and smallest diameter in a given cylinder bore. This value shall not exceed 0.0015 in. (0.038 mm) at any location. If the cylinder bore out-of-round, taper, and micro-finish are not within the specified tolerances, rehone the particular bore(s).
(d) After achieving the specified cylinder tolerances, calculate the average bore diameter for each cylinder using the middle and bottom transverse diameters. Record the average bore diameter and the calculated range of acceptable piston sizes that can be fitted in each bore. These data will be used when fitting pistons to specific cylinders.
NOTE 5 - Final sizing of the cylinder bores depends on the pistons available for fitting.
126.96.36.199 Final Preparations - After honing, bore measurement, piston ring gap adjustments, and piston fitting, soak the block in agitated clean organic solvent (see 7.7.3) for 1 h. Rinse the block with a mixture of hot (> 60°C) water and tri-sodium phosphate detergent and flush out all oil and coolant passages until no residue appears. Final rinse with hot (60°C) water. Spray the block with aliphatic naphtha containing 10 % EF-411 oil by volume. Use compressed air to force air-drying. (Warning - Do not spray the aliphatic naphtha/EF-411 oil mixture into the coolant passages. Clear all passages with compressed air and wipe the cylinder bores with EF-411 oil.)
188.8.131.52 Inspection of Tin Plating Quality - Reject any pistons with tin plating that is peeling or flaking. Examine the skirt surfaces for discoloration. Remove any discoloration by rubbing the piston with a Scotch Brite 7445 pad. Reject any pistons from which discoloration cannot be removed.
184.108.40.206 Oversizes - Either of the piston oversizes included in the Sequence VE Test Engine Parts Kits, 0.2 or 0.5 mm, can be used. However, all pistons in a given engine shall be of the same nominal oversize. Tests starting after May 19, 1998, may use 0.5-mm pistons, modified in accordance with Annex A15 by C&F Tool and Die and inspected by Test Engineering, Inc. Use pistons modified in accordance with Annex A15 for all tests started on or after December 31, 1998, with 0.5-mm oversize pistons.
220.127.116.11 Measurement - Measure and record the piston diameter at the wrist pin centerline elevation, perpendicular to the wrist pin centerline, and across the extended tips of the piston skirts. Use the wrist pin centerline diameter to determine the fitted clearance. Piston taper is the difference between the perpendicular centerline diameter and the skirt diameter. Positive piston taper means the skirt diameter is greater than the perpendicular centerline diameter. The taper shall be positive and shall not exceed 0.0015 in. (0.038 mm).
18.104.22.168 Selection - Select each piston to provide a calculated 0.0014 to 0.0022-in. (0.036 to 0.056-mm) clearance to its bore. (Alternatively, the cylinder bores can be honed to fit the pistons on hand.) Install the pistons in their respective bores to verify each piston is properly sized.
NOTE 6 - Threading a feeler strip between the piston and the cylinder wall is a simple method to verify the piston-to-cylinder wall clearance. Remove the pistons for installation on the connecting rods.
7.8.11 Piston Rings:
22.214.171.124 Selection - Select the proper oversize piston rings to correspond with the nominal piston oversize. As an example, a 0.15-mm oversize ring corresponds with a 0.20-mm oversize piston, and a 0.45-mm oversize ring corresponds with a 0.50-mm oversize piston.
126.96.36.199 Ring Gap Adjustment - Enlarge both compression ring gaps on each piston-and-ring assembly to obtain the specified blowby flow rate. Ring gaps ranging from 0.048 to 0.096 in. (1.2 to 2.4 mm) have been used successfully in various laboratories. Any combination (wider or narrower top ring gap or second ring gap) is acceptable. Enlargement of the oil ring gaps is not necessary to achieve satisfactory control of the blowby flow rate.
(a) Position each ring in its respective cylinder with the ring positioner (see Fig. A3.37) so that the gaps are located at the center of the thrust side of the cylinder wall. Measure and record the ring gaps.
188.8.131.52 Installation - Remove burrs from the ring ends. Then, install the compression rings and the oil control rings on the pistons with the gaps located outside the skirt areas. The gaps should be staggered at approximately 180° intervals. The gaps should be located alternately toward the front and rear of the engine.
184.108.40.206 Side Clearance - Measurement of the ring side clearance is not required but can help prevent possible blowby flow rate control problems. The side clearance should be between 0.0010 and 0.0030 in. (0.025 and 0.075 mm).
7.8.12 Connecting Rods - Measure and record the big end oil orifice diameter. The orifice diameter shall be from 0.062 to 0.068 in. (1.57 to 1.72 mm). The orifice can be drilled to achieve the specified diameter.
7.8.13 Wrist Pins - Heat the small end of the connecting rod in a connecting rod heater (see 7.5.8). Insert the wrist pin through the piston and rod by hand and center the pin on the connecting rod. Commercial connecting rod heaters have a fixture to ensure precise centering of the pin. (Warning - In addition to other precautions, use extreme care when working around the connecting rod heater and handling the heated rods.)
7.8.14 Connecting Rod Bearings - Mark position numbers on the connecting rod bearings. Rinse the bearings in aliphatic naphtha, then in pentane, and air-dry. Weigh and record the weights of each bearing half.
7.8.15 Crankshaft - Inspect the bearing journals carefully. Polish the journal surfaces with Number 320 or 400 grit crocus cloth and EF-411 buildup oil. Measure and record the journal diameters. The maximum journal out-of-roundness shall be between 0.0000 and 0.0006 in. (0.000 and 0.015 mm). Spray the crankshaft with aliphatic naphtha containing 10 % EF-411 oil by volume.
7.8.16 Modify the crankshaft ignition trigger by drilling out the rivets, tapping the holes to accept a machine screw, and relocate the hall effect ring to obtain 28° BTDC, at 750 r/min.
7.8.17 Modify the cylinder head drain holes in accordance with Fig.2.
7.9 Assembling the Test Engine - Installations:
7.9.1 Crankshaft and Miscellaneous Cylinder Block Components - Install all oil gallery plugs. Remove the main bearing caps and install the main bearings in the cylinder block. Install the crankshaft and install the front cover. Install the main bearings in the main bearing caps and torque the main bearing caps to 85 +/- 5 lbf·ft (115 +/- 7 N·m). Install the front cover. Measure and record the main bearing clearances. The desired clearances are 0.0015 to 0.0020 in. (0.038 to 0.051 mm). The allowable clearances are 0.0008 to 0.0026 in. (0.020 to 0.066 mm).
7.9.2 Auxiliary Shaft Drive - Install the auxiliary shaft and the auxiliary shaft drive sprocket. Install a petcock with a provision for a drain hose on the right side of the block at the existing drain plug location.
7.9.3 Pistons - Install the pistons in the correct cylinder bores. Measure and record the rod bearing clearances. The desired clearances are 0.0015 to 0.0020 in. (0.038 to 0.051 mm). The allowable clearances are 0.0008 to 0.0026 in. (0.020 to 0.066 mm) for connecting rod and crankshaft main bearings.
7.9.4 Oil System Components - Install the oil pump, the oil pump pickup tube and screen assembly, and the oil pan.
7.9.5 Cylinder Head - Install the cylinder head on the cylinder block. Use new torque-to-yield cylinder head bolts. Do not use any sealing or anti-seizure compound on the cylinder head gasket. Lubricate the head bolts with EF-411 oil. Torque the head bolts in accordance with the sequence described in Footnote 14 in two stages: 55 +/- 5 lbf·ft (75 +/- 7 N·m) and an additional 90 to 100° clockwise rotation.
7.9.6 Camshaft and Related Components:
220.127.116.11 Install the camshaft.
18.104.22.168 Do not remove the oil in the new lifters. Fill the lifters with EF-411 using the lifter fill chamber, Part No. BX-390-1. This lifter fill chamber is available from the supplier shown in X2.1.13.
(a) Lifter Fill Chamber Operation - Install lifters in the lifter holding fixture in an upright position. Add sufficient quantities of EF-411 to cover lifters. One litre has proven satisfactory. Close chamber, start vacuum pump, and hold vacuum for 10 min. Maintain 15 - 20 in. Hg (381–508 mm) vacuum throughout filling. Release vacuum, open chamber, raise holding fixture, and allow lifters to drain for 10 min. in upright position. Coat the lifter bodies with buildup oil prior to installation. Replace buildup oil in lifter chamber after filling three sets of lifters. Install the lifters in the cylinder head.
22.214.171.124 Install 1995 kit rocker arms, using Ford service tool, Part No. T74P-6565A. Install the camshaft drive sprocket, and measure and record the camshaft end-float.
126.96.36.199 Install the auxiliary shaft sprocket and align the cam drive. Torque the sprockets in accordance with the procedure noted in Footnote 14. Install a new camshaft drive belt. Tension the camshaft drive belt in accordance with the procedure noted in Footnote 14. Sealer may be required on the camshaft drive sprocket bolts if they have been used before.
188.8.131.52 Install the camshaft baffle and check to ensure the camshaft baffle does not come in contact with the RAC interior surfaces. The correct mounting orientation of the baffle is shown in Fig.A3.24.
7.9.7 Rocker Arm Cover - Install.
7.9.8 Water Pump, Water Pump Drive, and Crankshaft Ignition-Trigger - Install modified crankshaft trigger, the water pump, and the water pump and crankshaft pulleys (part numbers E9TZ6312A and E69Z8509D) or FZZZ6312A and F27A8509BA. Install the camshaft drive belt cover.
7.9.9 Miscellaneous Parts - Install the intake manifold and insert the spacer between the upper and lower half of the intake manifold. Install the freeze plugs.
NOTE 7 - Alternatively, the intake manifold and freeze plugs can be installed after the engine is installed on the test stand.
7.10 Engine Installation on the Test Stand - Functions that are to be performed in a specific manner or at a specific time in the assembly process are noted.
7.10.1 Mounting the Engine on the Test Stand - Mount the engine on the test stand so that the flywheel friction face is 4.0 +/- 0.5° from vertical, with the front of the engine higher than the rear. The engine mounting system should be designed to minimize engine vibration at 750 and 2500 rpm (80 and 260 rad/s). Couple the engine directly to the dynamometer through a driveshaft. The engine cannot be used to drive any external engine accessory other than the water pump.
7.10.2 Flywheel Timing Index Calibration - If ignition timing is measured at the flywheel, calibrate the position of the flywheel index pointer to TDC of the number one cylinder (see 7.5.17) (Warning - A significant amount of backward crankshaft rotation can cause the timing belt to jump time because of the arrangement of the belt tensioner.)
7.10.3 Exhaust Manifold:
184.108.40.206 Installation - Install the required water-cooled exhaust manifold shown in Fig.A3.8 and Fig.3 (see supplier listed in X2.1.7).
220.127.116.11 Gas Sampling and Back-Pressure Measurement Fittings:
(a) The required fitting for exhaust gas sampling and back-pressure measurement is illustrated in Fig.3 and detailed in A3.5.
(b) Install the exhaust gas sample and exhaust back-pressure probes. Check all exhaust system connections to ensure they are secure.
(c) The exhaust back pressure/exhaust gas sample probes can be used until they become unserviceable. If the existing probes are not cracked, brittle, or deformed, clean the outer surface and clear all port holes. Check the probes for possible internal obstruction and reinstall the probes in the exhaust pipe. Stainless steel probes are generally serviceable for several tests; mild steel probes tend to become brittle after one test. (Warning - Exhaust gas is noxious.) (Warning - Any leaks in the connections to the sample probe will result in erroneous O2 readings and incorrect air-fuel ratio adjustment.)
7.10.4 Fuel Management System:
18.104.22.168 Fuel Rail Assembly:
(a) The fuel injectors may be used for several tests, provided the spray pattern and flow rate are checked (see 7.6.11). There is currently no specified life of the fuel injectors. Use only fuel injectors that have demonstrated flow rates of 3.7 to 4.5 oz (109 to 134 cm3) at 39 +/- 0.5 psi (269 +/- 3.4 kPa) for 60 s.
(b) Inspect the O-rings to ensure they are in good condition and will not allow air leaks. Install the fuel injectors into the fuel rail and into the lower intake manifold. Connect the wiring harness to the fuel injectors. The injectors should be paired so that Cylinders 1 and 4 and 2 and 3 are in parallel (see 22.214.171.124).
126.96.36.199 Injector Pulsing:
(a) The fuel injectors are pulsed in alternating pairs, the pairs consisting of Cylinders 1 and 4 and 2 and 3 respectively. A schematic diagram of the necessary external connections to the injector wiring harness is shown in Fig.A3.44. Each injector pair is pulsed once per crankshaft revolution, without respect to crankshaft position. Typical pulse widths measured on the Ford EEC-IV system are described in the following section. A drawing showing what a pulse width represents is shown in Fig.A3.45. The pulse widths will vary slightly from engine-to-engine, although they should remain consistent for a given engine at a given fuel pressure. The measurement of fuel injector pulse widths is not required, although the measurement is a useful diagnostic tool.
(b) Typical fuel injector pulse widths for Stage 1 are 7.000 to 7.500 ms (approximately 38-psig [262-kPa] fuel pressure), for Stage 2 are 6.700 to 7.200 ms (approximately 38-psig [262-kPa] fuel pressure), and for Stage 3 are 2.500 to 3.500 ms (approximately 30-psig [207-kPa] fuel pressure). (The test stages are detailed in Table 2.)
188.8.131.52 Different Methods Currently Used:
(a) The fuel management controller hardware is not specified. The fuel management methods currently in use can be divided into five basic types of systems; modified Ford EEC-IV, open-loop analog, open-loop digital, closed-loop analog, and closed-loop digital. Process flow diagrams of typical open-loop and closed-loop digital systems are detailed in Fig.A3.22 and Fig.A3.23. Whatever fuel management system is used, there are specific ramping performance requirements (see 184.108.40.206). Use adequate precautions to ensure the fuel injectors cannot function while the engine is shut down. In addition, design the fuel management system to prevent excessive fuel input during engine startup.
(b) Exercise great care in the design, manufacture, and operation of the fuel management system to ensure that lambda is properly controlled throughout the test. It is recommended that the laboratory utilize the modified Ford EEC-IV system or an analog or digital system available from the suppliers detailed in X2.1.14.
7.10.5 Ignition System:
220.127.116.11 Components - Modifications to the ignition system are required. Modify the wiring harness by removing all circular connectors, except for the crankshaft ignition trigger connection. Figure A3.49 shows the required distributorless ignition system connections.
18.104.22.168 Spark Plugs - Install new Motorcraft AWSF-44 or AWSF-44C spark plugs that have been gapped to between 0.042 and 0.046 in. (1.07 and 1.17 mm). Torque the spark plugs to between 5 and 10 lbf·ft (7 and 14 N·m). Install the spark plug wiring harness but do not install the distributor and ignition module at this time.
7.10.6 Crankcase Ventilation System:
22.214.171.124 Oil Separator - Cut the 1.25-in. (31.8-mm) inside diameter polyethylene hose to approximately 1.5-in. (38-mm) length and install the oil separator on the front of the RAC. Maintain the distance between the bottom of the separator adaptor (Item 4, Fig.A3.16) and the top of the RAC at 5.5 +/- 0.25 in. (139.7 +/- 6.4 mm) (see Fig.A3.15). The alignment of the oil separator with the RAC should provide a straight run with no offset (see Fig.A3.15 and Fig.A3.17). Maintain the separator assembly in a vertical position throughout the test. A bracket may be necessary to support the separator.
126.96.36.199 PCV Valve - Install clean hoses and a new, calibrated PCV valve as shown in Fig.A3.15 and Fig.A3.17. Use the elbow provided with the PCV valve to attach the 0.375-in. (9.53-mm) inside diameter hose. Attach a new 0.375-in. inside diameter hose to the three-way valve for each test. Maintain the PCV valve in a vertical position throughout the test.
188.8.131.52 AirHorn Adapter - Install a clean 0.625-in. (15.88- mm) inside diameter transparent hose to the air horn adapter (use new hose when the existing hose appears deteriorated).
184.108.40.206 Three-Way Valve - Install a clean three-way valve and attach the PCV valve hose. Install the remaining PCV valve hose between the three-way valve and the upper intake manifold (see Fig.A3.15). Do not allow the hose to flatten at the bend after installation.
220.127.116.11 Inspection - When the installation of the crankcase ventilation system is complete, inspect the system to ensure the configuration will allow all oil condensate to drain to the elbow underneath the upper intake manifold. The pipe elbow leading to the intake manifold should be the lowest point of the system.
7.10.7 Dipstick and Oil Fill Tubes - Install the dipstick tube into the port on the left-hand side of the engine. Install the oil fill tube in the monolithic timing port on the left side of the engine (see 7.4.3 and 7.4.4).
7.10.8 Intake Air Components - Install the throttle body and intake-air horn.
7.10.9 External Hose Replacement - Inspect all external hoses used on the test stand and replace any hoses that have become unserviceable. Check for internal wall separations that could cause flow restrictions. Check all connections to ensure security.