Engine System - General Information: Other Ford Explorer IV

Engine Oil Leaks

Note. When diagnosing engine oil leaks, the source and location of the leak must be positively identified prior to repair.

Prior to carrying out this procedure, clean all sealing surface areas with a suitable solvent to remove all traces of oil.

Engine Oil Leaks - Fluorescent Oil Additive Method

Use the UV Leak Detector Kit to carry out the following procedure for oil leak diagnosis.

1. Add 29.6 ml (1 oz.) of fluorescent additive to a minimum of 0.473L (1/2 qt) and a maximum of 0.946L (1 qt) engine oil and fill through the engine oil fill. If the oil is not premixed, the fluorescent additive will not have enough time to reach the crankcase, oil galleries and seal surfaces during this particular 15 minute test. The additive must be mixed with oil and added through the oil fill. Check the level on the oil level indicator to determine what amount of oil to premix. If it is in the middle of the crosshatch area or below the full mark, use 0.946L (1 qt), if it is at the full mark, use 0.473L (1/2 qt).
2. Run the engine for 15 minutes. Stop the engine and inspect all seal and gasket areas for leaks using the UV Leak Detector Kit. A clear bright yellow or orange area will identify the leak. For extremely small leaks, several hours may be required for the leak to appear.
3. At the end of the test, make sure the oil level is within the upper and lower oil indicator marks. Remove oil as necessary if it registers above the full mark.

Leakage Points - Underhood

Examine the following areas for oil leakage

1. Valve cover gaskets
2. Intake manifold gaskets
3. Cylinder head gaskets
4. Oil bypass filter
5. Oil filter adapter
6. Engine front cover
7. Oil filter adapter and filter body
8. Oil level indicator tube connection
9. Oil pressure sensor

Leakage Points - Under Engine - With Vehicle on Hoist

Examine the following areas for oil leakage

1. Oil pan gaskets
2. Oil pan sealer
3. Oil pan rear seal
4. Engine front cover gasket
5. Crankshaft front seal
6. Crankshaft rear oil seal
7. Crankshaft main bearing cap side bolts
8. Oil filter adapter and filter body
9. Oil cooler, if equipped

Leakage Points - With Transmission and Flywheel Removed

Examine the following areas for oil leakage

1. Crankshaft rear oil seal
2. Rear main bearing cap parting line
3. Rear main bearing cap and seals
4. Flywheel mounting bolt holes (with flywheel installed)
5. Camshaft rear bearing covers or pipe plugs at the end of oil passages

Oil leaks at crimped seams in sheet metal parts and cracks in cast or stamped parts can be detected when using the dye method.

Cylinder Leakage Detection

When a cylinder produces a low reading, use of the Engine Cylinder Leak Detection/Air Pressurization Kit will be helpful in pinpointing the exact cause.

The leakage detector is inserted in the spark plug hole, the piston is brought up to dead center on the compression stroke and compressed air is admitted.

Once the combustion chamber is pressurized, a special gauge included in the kit will read the percentage of leakage. Leakage exceeding 20% is excessive.

While the air pressure is retained in the cylinder, listen for the hiss of escaping air. A leak at the intake valve will be heard in the throttle body. A leak at the exhaust valve can be heard at the tail pipe. Leakage past the piston rings will be audible at the positive crankcase ventilation (PCV) connection. If air is passing through a blown head gasket to an adjacent cylinder, the noise will be evident at the spark plug hole of the cylinder into which the air is leaking. Cracks in the cylinder block or gasket leakage into the cooling system may be detected by a stream of bubbles in the radiator.

Excessive Engine Oil Consumption

Nearly all engines consume oil, which is essential for normal lubrication of the cylinder bore walls and pistons and rings. Determining the level of oil consumption may require testing by recording how much oil is being added over a given set of miles.

Customer driving habits greatly influence oil consumption. Mileage accumulated during towing or heavy loading generates extra heat. Frequent short trips, stop-and-go type traffic or extensive idling, prevent the engine from reaching normal operating temperature. This prevents component clearances from reaching specified operating ranges.

The following diagnostic procedure may be utilized to determine internal oil consumption. Make sure that the concern is related to internal oil consumption, and not external leakage, which also consumes oil. Verify there are no leaks before carrying out the test. Once verified, the rate of internal oil consumption can be tested.

A new engine may require extra oil in the early stages of operation. Internal piston-to-bore clearances and sealing characteristics improve as the engine breaks in. Engines are designed for close tolerances and do not require break-in oils or additives. Use the oil specified in the Owner Guide. Ambient temperatures may determine the oil viscosity specification. Verify that the correct oil is being used for the vehicle in the geographic region in which it is driven.

Basic Pre-Checks

1. For persistent complaints of oil consumption, interview the customer to determine the oil consumption characteristics. If possible, determine the brand and grade of oil currently in the oil pan. Look at the oil filter or oil-change station tags to determine if Ford-recommended maintenance schedules have been followed. Make sure that the oil has been changed at the specified mileage intervals. If vehicle mileage is past the first recommended drain interval, the OEM production filter should have been changed.
2. Ask how the most current mileage was accumulated. That is, determine whether the vehicle was driven under the following conditions: Extended idling or curbside engine operation Stop-and-go traffic or taxi operation Towing a trailer or vehicle loaded heavily Frequent short trips (engine not up to normal operating temperature) Excessive throttling or high engine-rpm driving
3. Verify that there are no external leaks. If necessary, review the diagnostic procedure under «Engine Oil Leaks»(ref-270909-S17543554832007110700000) .
4. Inspect the crankcase ventilation system for: disconnected hoses at the valve cover or throttle body. loose or missing valve cover fill cap. missing or incorrectly seated engine oil level indicator. incorrect or dirty PCV valve. a PCV valve grommet unseated in the valve cover (if so equipped).
5. Inspect for signs of sludge. Sludge affects PCV performance and can plug or restrict cylinder head drainback wells. It can also increase oil pressure by restricting passages and reducing the drainback capability of piston oil control rings. Sludge can result from either excessive water ingestion in the crankcase or operation at extremely high crankcase temperatures.
6. Inspect the air filter for dirt, sludge or damage. A hole in the filter element will allow unfiltered air to bypass into the air induction system. This can cause premature internal wear (engine dusting), allowing oil to escape past rings, pistons, valves and guides.
7. If the engine is hot or was recently shut down, wait at least 5 minutes to allow the oil to drain back. Ask the customer if this requirement has been followed. Adding oil without this wait period can cause an overfill condition, leading to excessive oil consumption and foaming which may cause engine damage.
8. Make sure the oil level indicator (dipstick) is correctly and fully seated in the indicator tube. Remove the oil level indicator and record the oil level.

Detailed Pre-Checks

1. Check the thermostat opening temperature to make sure that the cooling system is operating at the specified temperature. If it is low, internal engine parts are not running at specified internal operating clearances.
2. Verify the spark plugs are not oil saturated. Oil leaking into one or more cylinders will appear as an oil soaked condition on the plug. If a plug is saturated, a compression check may be necessary at the conclusion of the oil consumption test.

Post Checks, Evaluation and Corrective Action

1. If test results indicate excessive oil consumption, carry out a cylinder compression test. The cylinder compression test should be carried out with a fully charged battery and all spark plugs removed. See the «COMPRESSION PRESSURE LIMIT CHART»(ref-270909-S04950798142007111500000) for pressure range limits.
2. Compression should be consistent across all cylinders. For additional information, refer to «Compression Test - Compression Gauge Check»(ref-270909-S34724915112007110700000) . If compression tested within «SPECIFICATIONS»(ref-270909-S34109612702007110700000) , the excessive oil consumption may be due to wear on the valve guides, valves or valve seals.
3. A cylinder leak detection test can be carried out using an Engine Cylinder Leak Detection/Air Pressurization Kit. This can help identify valves, piston rings, or worn valve guides/valve stems, inoperative valve stem seals or other related areas as the source of oil consumption.
4. If an internal engine part is isolated as the root cause, determine if the repair will exceed cost limits and proceed with a repair strategy as required.
5. Once corrective action to the engine is complete and verification of all pre-check items were eliminated in the original diagnosis, repeat the Oil Consumption Test as described above and verify consumption results.

Valve Train Analysis - Engine Off - Valve Cover Removed

Check for damaged or severely worn parts and correct assembly. Make sure correct parts are used with the static engine analysis as follows

Valve Train Analysis - Engine Off, Rocker Arm

1. Check for loose mounting bolts, studs and nuts.
2. Check for plugged oil feed in the rocker arms or cylinder head.

Valve Train Analysis - Engine Off, Camshaft Roller Followers and Hydraulic Lash Adjusters, Overhead Camshaft

1. Check for loose mounting bolts on camshaft carriers.
2. Check for plugged oil feed in the camshaft roller followers, lash adjusters or cylinder heads.

Valve Train Analysis - Engine Off, Camshaft - Engines

1. Check for broken or damaged parts.

Valve Train Analysis - Engine Off, Push Rods

1. Check for bent push rods and restricted oil passage.

Valve Train Analysis - Valve Springs

1. Check for broken or damaged parts.

Valve Train Analysis - Engine Off, Valve Spring Retainer and Valve Spring Retainer Keys

1. Check for correct seating of the valve spring retainer key on the valve stem and in valve spring retainer.
2. Check for correct seating on the valve stem.

Valve Train Analysis - Engine Off, Valves and Cylinder Head

1. Check for plugged oil drain back holes.
2. Check for worn or damaged valve tips.
3. Check for missing or damaged guide-mounted valve stem seal.
4. Check collapsed valve tappet gap.
5. Check installed valve spring height.
6. Check for missing or worn valve spring seats.
7. Check for plugged oil metering orifice in cylinder head oil reservoir (if equipped).

Static checks (engine off) are to be made on the engine prior to the dynamic procedure.

Valve Train Analysis - Engine Running

Start the engine and, while idling, check for correct operation of all parts. Check the following

Valve Train Analysis - Engine Running, Valves and Cylinder Head

1. Check for plugged oil drain back holes.
2. Check for missing or damaged valve stem seals or guide-mounted valve stem seals.
3. Check for a plugged oil metering orifice in the cylinder head oil reservoir (4.6L engine only).

If insufficient oiling is suspected, check oil passages for blockage, then accelerate the engine to 1,200 rpm with the transmission in NEUTRAL and the engine at normal operating temperature. Oil should spurt from the rocker arm oil holes such that valve tips and camshaft roller followers are well oiled. With the valve covers off, some oil splash may overshoot camshaft roller followers.

Valve Train Analysis - Engine Running, Camshaft Lobe Lift - OHC Engines

Check the lift of each camshaft lobe in consecutive order and make a note of the readings.

1. Remove the valve covers.
2. Remove the spark plugs.
3. Install the Dial Indicator Gauge with Holding Fixture so the rounded tip of indicator is on top of the camshaft lobe and on the same plane as the valve tappet.
4. Rotate the crankshaft using a breaker bar and socket attached to the crankshaft pulley retainer bolt. Rotate the crankshaft until the base circle of the camshaft lobe is reached.
5. Zero the dial indicator. Continue to rotate the crankshaft until the (1) high-lift point of the camshaft lobe is in the fully-raised position (highest indicator reading).
6. To check the accuracy of the original indicator reading, continue to rotate crankshaft until the (2) base circle is reached. The indicator reading should be zero. If zero reading is not obtained, repeat Steps 1 through 6.
7. Remove the Dial Indicator Gauge with Holding Fixture.
8. Install the spark plugs.
9. Install the valve covers.

Valve Train Analysis - Engine Running, Camshaft Lobe Lift - Push Rod Engine

Check the lift of each lobe in consecutive order and make a note of the readings.

1. Remove the valve covers.
2. Remove the rocker arm seat bolts, rocker arm seat and rocker arms.
3. Make sure the valve tappet is seated against the camshaft. Install (1) Dial Indicator Gauge with Holding Fixture so the ball socket adapter of the indicator is on top of the valve tappet or (2) Dial Indicator Gauge Adapter is on top of the push rod and in the same plane as the valve tappet push rod movement.
4. Remove the spark plugs.
5. Connect an auxiliary starter switch in the starting circuit. Crank the engine with the ignition switch in the OFF position. Bump the crankshaft over until the valve tappet is on the base circle of the camshaft lobe. At this point, the valve tappet will be in its lowest position. If checking during engine assembly, turn the crankshaft using a socket or ratchet.
6. Zero the dial indicator. Continue to rotate the crankshaft slowly until the valve tappet is in fully-raised position (highest indicator reading).
7. Remove the Dial Indicator with Holding Fixture, Dial Indicator Gauge Adapter and auxiliary starter switch.
8. Install the rocker arm seats, the rocker arms and the rocker arm seat bolts.
9. Install the valve covers.
10. Install the spark plugs.

Valve Train Analysis - Engine Running, Valve Tappet

Valve tappet noise can be caused by any of the following

1. Excessive valve tappet gap (collapsed)
2. Incorrectly functioning valve tappet
3. Air in lubrication system
4. Excessive valve guide wear
5. Low oil pressure

Excessive collapsed valve tappet gap can be caused by loose rocker arm seat bolts/nuts, incorrect initial adjustment or wear of the valve tappet face, or worn roller valve tappets, push rod, rocker arm, rocker arm seat or valve tip. With the valve tappet collapsed, check the gap between the valve tip and the rocker arm to determine if any other valve train parts are damaged, worn or out of adjustment.

An incorrectly functioning valve tappet can be sticking, caused by contaminants or varnish inside the tappet. The tappet can have a check valve that is not functioning correctly, which can be caused by an obstruction, such as dirt or chips that prevent the check valve from closing, or a broken check valve spring. A tappet with a leak-down time out of specification can cause tappet noise. If no other cause for noisy valve tappets can be found, the leak-down rate should be checked and new valve tappets installed if found to be out of specification.

Assembled valve tappets can be tested with Hydraulic Lash Adjuster Leak-down Tester to check the leak-down rate. The leak-down rate specification is the time in seconds for the plunger to move a specified distance while under a 22.7 kg (50 lb) load.

Air bubbles in the lubrication system will prevent the valve tappet from supporting the valve spring load. This can be caused by too high or too low an oil level in the oil pan or by air being drawn into the system through a hole, crack or leaking gasket on the oil pump screen cover and tube.

Sprockets

1. Inspect the timing chain/belt and the sprockets. Install new components as necessary. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Camshaft Bearing Journal Diameter

Note. Refer to SPECIFICATIONS .

1. Measure each camshaft journal diameter in 2 directions.

Camshaft Bearing Journal Clearance

Note. The camshaft journals must meet specifications before checking camshaft journal clearance.

1. Remove the camshaft bearing cap and lay Plastigage across the surface. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .
2. Position the camshaft bearing cap and install the bolts. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .
3. Use Plastigage to verify the camshaft journal clearance. If out of specification, install new components as necessary. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Camshaft End Play

Special Tools Illustration Tool Name Tool Number Dial Indicator with Brackets 100-002 (TOOL-4201-C) or equivalent

1. Remove the roller followers. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .
2. Use the special tool to measure camshaft end play.
3. Position the camshaft to the rear of the cylinder head.
4. Zero the indicator.
5. Move the camshaft to the front of the cylinder head. Note and record the camshaft end play. If camshaft end play exceeds specifications, install new camshaft and recheck end play. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) . If camshaft end play exceeds specification after camshaft installation, install a new cylinder head. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Camshaft Lobe Lift

Special Tools Illustration Tool Name Tool Number Dial Indicator with Brackets 100-002 (TOOL-4201-C) or equivalent

1. Use the special tool to measure camshaft intake/exhaust lobe lift. Rotate the camshaft and subtract the lowest indicator reading from the highest indicator reading to figure the camshaft lobe lift. For additional information, refer to «SPECIFICATIONS»(ref-270909-S34109612702007110700000) .

Camshaft Runout

Special Tools Illustration Tool Name Tool Number Dial Indicator with Brackets 100-002 (TOOL-4201-C) or equivalent

1. Use the special tool to measure the camshaft runout. Rotate the camshaft and subtract the lowest indicator reading from the highest indicator reading. For additional information, refer to «SPECIFICATIONS»(ref-270909-S34109612702007110700000) . If out of specification, install new components as necessary. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Crankshaft Main Bearing Journal Diameter

Note. Refer to SPECIFICATIONS .

1. Measure each of the crankshaft main bearing journal diameters in at least 2 directions.

Crankshaft Main Bearing Journal Taper and Out-of-Round

Note. Refer to SPECIFICATIONS .

1. Measure each of the crankshaft main bearing journal diameters in at least 2 directions at each end of the main bearing journal.

Crankshaft Main Bearing Journal-to-Bearing Clearance

Note. Refer to SPECIFICATIONS .

Note. Crankshaft main bearing journals must be within specifications before checking journal clearance.

1. Remove the crankshaft main bearing caps and crankshaft main bearing.
2. Lay a piece of Plastigage across the face of each crankshaft main bearing surface.
3. Install and remove the crankshaft main bearing cap.
4. Verify the crankshaft journal clearance.

Crankshaft End Play

Special Tools Illustration Tool Name Tool Number Dial Indicator with Brackets 100-002 (TOOL-4201-C) or equivalent

1. Measure the crankshaft end play. Use the special tool to measure crankshaft end play.
2. Position the crankshaft to the rear of the cylinder block.
3. Zero the indicator.
4. Move the crankshaft to the front of the cylinder block. Note and record the crankshaft end play. If crankshaft end play exceeds specifications, install a new crankshaft thrust washer or crankshaft thrust main bearing. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Crankshaft Runout

Special Tools Illustration Tool Name Tool Number Dial Indicator with Brackets 100-002 (TOOL-4201-C) or equivalent

Note. Refer to SPECIFICATIONS .

1. Use the special tool to measure the crankshaft runout. Rotate the crankshaft and subtract the lowest dial indicator reading from the highest dial indicator reading to figure the crankshaft runout.

Connecting Rod Bearing Journal Taper and Out-of-Round

Note. Refer to SPECIFICATIONS .

1. Measure the crankshaft connecting rod journal diameters in 2 directions perpendicular to one another at each end of the connecting rod journal. The difference in the measurements from one end to the other is the taper. Verify measurement is within the wear limit.

Cylinder Bore Taper

Note. Refer to SPECIFICATIONS .

1. Measure the cylinder bore at the top, middle and bottom of piston ring travel in 2 directions as indicated. Verify the cylinder bore is within the wear limit. The difference indicates the cylinder bore taper. Bore the cylinder to the next oversize limit.

Cylinder Bore Out-of-Round

Note. Refer to SPECIFICATIONS .

1. Measure the cylinder bore in 2 directions. The difference is the out-of-round.

Piston Pin Bore Diameter

Note. Refer to SPECIFICATIONS .

1. Measure the piston pin bore diameter in 2 directions on each side. Verify the diameter is within specification.

Piston Diameter

Note. Refer to SPECIFICATIONS .

1. Measure the piston diameter 90 degrees from the piston pin and 42 mm (1.65 in) down from the top of the piston at the point indicated.

Piston To Cylinder Bore Clearance

Note. Refer to SPECIFICATIONS .

1. Subtract the piston diameter from the cylinder bore diameter to find the piston-to-cylinder bore clearance.

Piston Selection

Note. The cylinder bore must be within the specifications for taper and out-of-round before fitting a piston.

1. Select a piston size based on the cylinder bore.
2. Choose the piston with the correct paint color. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Piston Ring End Gap

Note. Piston rings should not be transferred from one piston to another.

Note. Refer to SPECIFICATIONS .

Note. The cylinder bore must be within specification for taper and out-of-round.

1. Use a piston without rings to push a piston ring in a cylinder to the bottom of ring travel.
2. Use a feeler gauge to measure the top piston ring end gap and the second piston ring end gap.

Piston Ring-to-Groove Clearance

Note. Refer to SPECIFICATIONS .

1. Inspect the piston for ring land damage or accelerated wear.
2. Measure the piston ring-to-groove clearance.

Piston Pin Diameter

Note. Refer to SPECIFICATIONS .

1. Measure the piston pin diameter in 2 directions at the points shown. Verify the diameter is within specification.

Connecting Rod Cleaning

1. Mark and separate the parts and clean with solvent. Clean the oil passages.

Connecting Rod Large End Bore

Note. Refer to SPECIFICATIONS .

1. Tighten the bolts to specification, then measure the bore in 2 directions. The difference is the connecting rod bore out-of-round. Verify the out-of-round is within specification.

Connecting Rod Bushing Diameter

Note. Refer to SPECIFICATIONS .

1. Use a telescoping gauge to determine the inner diameter of the connecting rod bushing, if equipped.
2. Measure the telescoping gauge with a micrometer. Verify the diameter is within specification.

Connecting Rod Bend

Note. Refer to SPECIFICATIONS .

1. Measure the connecting rod bend on a suitable alignment fixture. Follow the instructions of the fixture manufacturer. Verify the bend measurement is within specification.

Connecting Rod Twist

Note. Refer to SPECIFICATIONS .

1. Measure the connecting rod twist on a suitable alignment fixture. Follow the instructions of the fixture manufacturer. Verify the measurement is within specification.

Piston Wrist Pin Side Clearance

1. Measure the clearance between the connecting rod and the piston. Verify the measurement is within specification. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) . If out of specification, install new components as necessary. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Connecting Rod Bearing Journal-to-Bearing Clearance

Note. The crankshaft connecting rod journals must be within specifications to check the connecting rod bearing journal clearance.

1. Remove the connecting rod bearing cap.
2. Position a piece of Plastigage across the bearing surface.
3. Install and tighten to specifications, then remove the connecting rod bearing cap.
4. Measure the Plastigage to get the connecting rod bearing journal clearance. The Plastigage should be smooth and flat. A changing width indicates a tapered or damaged connecting rod or connecting rod bearing. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) . If out of specification, install new components as necessary. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Valve Stem Diameter

Note. Refer to SPECIFICATIONS .

1. Measure the diameter of each intake and exhaust valve stem at the points shown. Verify the diameter is within specification.

Valve Stem to Valve Guide Clearance

Special Tools Illustration Tool Name Tool Number Dial Indicator with Brackets 100-002 (TOOL-4201-C) or equivalent Valve Guide Clearance Gauge 303-004 (TOOL-6505-E) or equivalent

Scheme 90

Note. Valve stem diameter must be within specifications before checking valve stem to valve guide clearance.

1. Install a valve clearance gauge on the valve stem and install a dial indicator. Lower the valve until the valve clearance gauge contacts the upper surface of the valve guide.
2. Move the valve clearance gauge toward the indicator and zero the indicator. Move the valve clearance gauge away from the indicator and note the reading. The reading will be DOUBLE the valve stem-to-valve guide clearance. Valves with oversize stems will need to be installed if out of specification.

Valve Guide Inner Diameter

Note. Refer to SPECIFICATIONS .

1. Use a ball gauge to determine the inner diameter of the valve guides in 2 directions at the top, middle and bottom of the valve guide.
2. Measure the ball gauge with a micrometer.
3. If the valve guide is not within specifications, install a new cylinder head assembly.

Valve Guide Reaming

1. Use a hand-reaming kit to ream the valve guide.
2. Reface the valve seat.
3. Clean the sharp edges left by reaming.

Valve Spring Installed Length

Note. Refer to SPECIFICATIONS .

1. Measure the installed length of each valve spring.

Valve Spring Free Length

Note. Refer to SPECIFICATIONS .

1. Measure the free length of each valve spring.

Valve Spring Squareness

1. Measure the out-of-square on each valve spring. Turn the valve spring and observe the space between the top of the valve spring and the square.

Valve Spring Strength

Special Tools Illustration Tool Name Tool Number Valve/Clutch Spring Tester 303-006 (TOOL-6513-DD) or equivalent

1. Use a spring tester to check the valve spring for correct strength at the specified valve spring length. For additional information, refer to «SPECIFICATIONS»(ref-270909-S34109612702007110700000) . If out of specification, install new components as necessary. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) .

Valve and Seat Refacing Measurements

1. Check the valve head and seat. Check valve angles. Check margin width. Refer to «ENGINE - 4.0L SINGLE OVERHEAD CAMSHAFT (SOHC)»(ref-270889) or «ENGINE - 4.6L (3V)»(ref-270890) . Be sure margin width is within specification.
2. Inspect for abnormalities on the valve face and seat.

Valve Seat Width

Note. Refer to SPECIFICATIONS .

1. Measure the valve seat width. If necessary, grind the valve seat to specification. Measure the intake valve seat width. Measure the exhaust valve seat width. Recheck the valve spring installed length after the seats have been ground, and shim the valve springs as necessary to achieve the correct installed spring length.

Valve Seat Runout

Note. Refer to SPECIFICATIONS .

1. Use a valve seat runout gauge to check valve seat runout.

Cylinder Head Distortion

Special Tools Illustration Tool Name Tool Number Feeler Gauge Set 303-D027 (D81L-4201-A) or equivalent Straight Edge 303-D039 (D83L-4201-a) or equivalent

Scheme 91

1. Using a straight edge and a feeler gauge, inspect the cylinder head for flatness in the sequence shown. If the cylinder head is distorted, install a new cylinder head.

Cylinder Bore Cleaning

Material

1. Clean the cylinder bores with soap or detergent and water.
2. Thoroughly rinse with clean water and wipe dry with a clean, lint-free cloth.
3. Use a clean, lint-free cloth and lubricate the cylinder bores. Use clean engine oil meeting Ford specification.