Disassembly
NOTE: Before beginning disassembly procedures, carefully drain fluids as follows:1. Remove the oil pan drain bolt and allow oil to drain from the oil pan.
2. Remove the oil filter.
3. Remove coolant jacket drain plugs and allow coolant to drain from cooling jacket.
4. Install oil pan drain bolt and the coolant jacket plugs.
a. Tighten Oil Pan Drain Bolt to 26 Nm (19 lb ft).
b. Tighten Coolant Jacket Plugs to 30 Nm (22 lb ft).
5. If cleaning or repairing engine block it is not necessary to reinstall the plugs.
TOOL REQUIRED
^ J 38122 Crankshaft Balancer Holder
^ J 24420-B Crankshaft Balancer Puller
^ J 36008-A Camshaft Sprocket Timing Pins
^ J 39579 Camshaft Sprocket Wrench
^ J 38188 Cylinder Head Broken Bolt Extractor Kit
1. Engine Flywheel Removal
NOTE: It may be necessary to remove the chamfer (bevel) from the edge of an 18 mm socket in order to get full socket engagement on the thin headed flex plate bolts. Do not orientate the flex plate to the crankshaft. It is balanced separately from the engine.
a. Remove the flex plate attaching bolt. Use the crankshaft balancer holder to prevent crankshaft rotation.
b. Remove the flywheel, if the vehicle has a manual transmission.
c. Remove the flex plate retainer for vehicles with automatic transmission.
d. Remove the flex plate, if the vehicle has an automatic transmission.
e. Clean the thread adhesive from the flex plate bolt holes. Use a nylon-bristle brush to clear, the holes in the crankshaft.
2. Oil Level Indicator and Tube Removal
a. Remove the tube bracket to the rear cam carrier lift bracket bolt.
b. Remove the tube from the block.
3. Exhaust Manifold Removal
a. Remove the exhaust manifold brace to the manifold bolt.
b. Remove the exhaust manifold heat shield, if the exhaust manifold is being replaced.
c. Remove the exhaust manifold to the cylinder head retaining nuts.
d. Remove the exhaust manifold.
e. Clean all of the sealing surfaces.
f. If the exhaust manifold is being replaced, transfer the following parts:
^ The exhaust manifold nuts.
^ The exhaust manifold heat shield.
4. EGR Valve Adapter Removal
a. Remove the EGR valve bolts.
b. Remove the EGR valve.
c. Remove the EGR tube bolts.
d. Remove the EGR tube. The EGR tube seal is reusable if it is not damaged.
e. Remove the EGR adapter bolts.
f. Remove the EGR adapter.
5. Intake Manifold Removal
CAUTION: Never attempt to remove the intake manifold from a hot engine, allow the engine to cool to ambient temperature. The intake manifold is made of a composite plastic and can be damaged if it is removed when the engine is hot.
a. Remove the throttle body.
b. Disconnect the fuel pressure regulator hose.
c. Remove the EGR pipe from the EGR adapter.
d. Remove the intake manifold retaining nuts and bolts.
e. Remove the intake manifold.
f. Remove the intake manifold gasket. The gasket is reusable if it is not damaged.
g. Remove the EGR pipe from the intake manifold.
h. If the intake manifold needs to be replaced, transfer the following parts:
^ The throttle body
^ The throttle body gasket. The manifold to the throttle body gasket is reusable if it is not damaged.
^ The EGR tube. The O-ring is reusable if it is not damaged.
6. Crankshaft Balancer and Hub Removal
NOTE: An automatic transmission crankshaft balancer must not be installed on a manual transmission equipped engine. A manual transmission crankshaft balancer must not be installed on an automatic transmission equipped engine.
a. Remove the balancer retaining bolt and washer. Use the crankshaft balancer holder in order to prevent the crankshaft from rotating when loosening the bolt.
b. Remove the balancer assembly. Use the crankshaft balancer puller.
7. Timing Chain, Sprockets, and Tensioner Removal
CAUTION: The timing chain is not to be replaced with the timing chain from any other model year. The timing sprockets are different on the Twin Cam engine and the shape of the links matches the sprockets. Engine damage may result if the wrong timing chain is used. The timing chain and the crankshaft sprocket must be marked so that they are reinstalled in the same side facing out at the time of reassembly.
NOTE: Read the entire procedure before removing the timing chain.
a. Mark the timing chain and the crankshaft sprocket outer surfaces for reassembly. Ensure that this is done in order to prevent noise and increased wear on the chain.
b. Remove the timing chain guides.
c. Reload the timing chain tensioner assembly to its "zero" position. Use the following steps:
^ Form a keeper from a piece of heavy gauge wire.
^ Apply slight force on the tensioner shoe to compress the plunger.
^ Insert a small screwdriver into the reset access hole.
^ Pry the ratchet pawl away from the ratchet teeth while forcing the plunger completely in the hole.
^ Install the keeper between the access hole and the blade.
^ Remove the tensioner assembly retaining bolts.
d. Remove the tensioner. Ensure all of the slack in the timing chain is above the tensioner assembly when the tensioner is removed.
e. Remove the timing chain.
f. Inspect the parts for wear, replace them as required.
g. Replace the timing chain shoe or guides if the scoring exceeds 1.12 mm (0.045 inch).
8. Water Pump Removal
NOTE: The timing chain tensioner must be compressed to unload chain tension before the water pump is removed. If it is not, the water pump will become cocked in the timing chain housing and it will be difficult to remove.
a. Rotate the timing chain sprockets to line up the holes. Install the camshaft sprocket timing pins.
b. Compress the tensioner. Use a tool to hold the compressed tensioner.
c. Remove the bolts holding the tensioner in place.
d. Remove the water pump cover to the cylinder block bolts.
e. Remove the water pump assembly to the timing chain housing nuts.
f. Remove the water pump cover assembly.
g. Remove the water pump.
h. Remove the water pump cover to the water pump assembly bolts.
i. Clean all of the sealing surfaces.
9. Timing Chain Housing Removal
a. Remove the camshaft sprocket retaining bolts and washers. Use the camshaft sprocket wrench to hold the sprockets when removing the bolts.
b. Remove the camshaft sprockets. The sprockets are interchangeable, no marking is required.
c. Remove the four oil pan bolts.
d. Remove the timing chain housing to the camshaft housing bolts.
e. Remove the timing chain housing to the block bolts.
f. Remove the timing chain housing.
g. Remove the timing chain gaskets.
10. Intake Camshaft, Housing and Lifter Removal
NOTE: Use this procedure only if the camshaft or lifters are going to be removed. Read the entire procedure before removing the camshaft housing. Replace the camshaft housing to cylinder head gasket any time the camshaft housing to cylinder head bolts are loosened or removed. Ensure that the valve lifters are kept together and identified during disassembly. Do this in order to ensure that they are installed in their original location.
a. Remove the camshaft housing cover to the camshaft housing retaining bolts.
NOTE: Use the reverse of the tightening procedure when loosening the camshaft housing to the cylinder head retaining bolts. Leave the bolts loosely in place to hold the camshaft housing while separating the camshaft cover from the housing.
b. Remove the camshaft housing to the cylinder head retaining bolts.
c. Remove the camshaft sensor bolt.
d. Remove the camshaft sensor.
CAUTION: Push the cover off of the housing. Remove it by threading four of the housing to head retaining bolts into the tapped holes in the camshaft housing cover. Tighten the bolts evenly in order to prevent the cover from binding on the dowel pins.
e. Remove the two loosely installed camshaft housing to head bolts.
f. Remove the camshaft housing cover. Discard the seals.
g. Loosely reinstall one camshaft housing to the cylinder head bolt in order to retain the housing during camshaft and lifter removal.
h. Remove the camshaft. Be careful not to damage the camshaft or journals.
NOTE: Keep the valve lifters in order so they can be installed in the same location.
i. Remove the valve lifters.
j. Use the following steps to minimize lifter bleed down:
^ Store the lifters upside down on a level surface. Keep the camshaft contact surface down.
^ The lifters can also be submerged in clean engine oil.
k. Replace the lifters if, they are faulty. These lifters are not repairable.
l. Coat the lifter with Camshaft and Lifter Prelube GM P/N 12345501 or equivalent. Do not get the prelube on the camshaft cover seals because they could swell.
m. Add Engine Oil Supplement GM P/N 1052367 or equivalent to the engine oil.
n. Remove the camshaft housing.
o. Remove the camshaft housing gasket.
11. Exhaust Camshaft, Housing and Lifter Removal
a. Read the entire procedure before removing the camshaft housing.
b. The camshaft housing to the cylinder head gasket must be, replaced any time the camshaft housing to the cylinder head bolts are loosened or removed.
c. During disassembly, be sure that the valve lifters are kept together and identified in order to be reinstalled in their original locations.
d. Remove the exhaust camshaft rear cover.
e. Remove the exhaust camshaft rear cover gasket.
NOTE: Use the reverse of the tightening procedure when loosening the camshaft housing to the cylinder head retaining bolts.
f. Remove the exhaust camshaft housing to the cylinder head bolts.
NOTE: Leave two bolts loosely in place to hold the camshaft housing while separating the camshaft cover from the housing.
g. Push the cover off the camshaft housing by threading four of the housing to the head retaining bolts into the tapped holes in the camshaft cover.
CAUTION: Tighten the bolts evenly to prevent the cover from binding on the dowel pins.
h. Remove the two loosely installed camshaft housing to the head bolts.
i. Remove the camshaft cover. Discard the seals.
j. Loosely install one camshaft housing to the cylinder head bolt to retain the housing during the camshaft and lifter removal.
k. Remove the camshaft. Be careful not to damage the camshaft or journals.
l. Remove the valve lifters. Keep the valve lifters in order so they may be reinstalled in the same location from which they were removed.
m. Do one of the following to minimize lifter bleed down:
^ Store the lifters upside down on, a level surface.
^ Store the lifters submerged in clean engine oil.
NOTE: The valve lifters are not repairable. Replace the lifters if they are faulty. Do not prelube on the camshaft cover seals because they will swell. Coat the lifter with Camshaft and Lifter Prelube GM P/N 12345501 or equivalent. If new lifters are installed, add Engine Oil Supplement GM P/N 1052367 or equivalent to the engine oil.
n. Remove the camshaft housing.
o. Remove the camshaft housing gasket.
12. Cylinder Head Removal
a. Remove the cylinder head to the block bolts. Follow the reverse of the tightening sequence.
b. Remove the cylinder head.
c. Remove the cylinder head gasket.
CAUTION: Engine damage may result if an abrasive paper, pad, or motorized wire brush is used to clean any engine gasket surfaces.
d. Clean all of the gasket surfaces.
e. Use the following procedures when cleaning the cylinder head and cylinder block surfaces:
^ Use a razor blade gasket scraper to clean the cylinder head and cylinder block gasket surfaces.
^ Use a razor blade gasket scraper to clean the cylinder head and cylinder block gasket surfaces. Do not scratch or gouge any surface.
NOTE: Do not use any other method or technique to clean these gasket surfaces. Use a new razor blade for each cylinder head and cylinder block.
CAUTION: Be careful not to gouge or scratch the gasket surfaces. Do not gouge or scrape the combustion chamber surfaces. The feel of the gasket surface is important, not the appearance. There will be indentations from the gasket left in the cylinder head after all to the gasket material is removed. These small indentations will be filled in by the new gasket. Hold the razor blade as parallel to the gasket surface as possible. Do not use a tap to clean the cylinder head bolt holes.
f. Clean the old sealer/lube and dirt from the bolt, the studs and the bolt holes.
g. Clean the bolt holes with a nylon bristle brush.
WARNING: Wear safety glasses to avoid injury when using compressed air, carburetor cleaner or any cleaning solvent. Bodily injury may occur if fumes are inhaled or if skin is exposed to chemicals.
h. When cleaning the cylinder head bolt holes 1-8 use a suitable commercial spray liquid solvent and compressed air from an extended-tip blow gun to reach the bottom of the holes.
i. Remove any broken long cylinder head bolts using the cylinder head broken bolt extractor kit.
13. Oil Filter Adapter and Valve Assembly Removal
a. Remove the oil filter.
b. Be sure that the gasket is removed with the filter.
c. Remove the oil filter adapter.
d. Remove the oil filter bypass valve using a screwdriver or punch to pry the valve out.
e. Clean the oil filter mounting surface.
14. Oil Pan Removal
a. Remove the oil pan bolts.
b. Remove the oil pan. Reuse the oil pan gasket if it is not damaged.
c. Inspect the oil pan gasket for damage before reusing the casket. Replace it if necessary.
15. Oil Pump Removal
a. Remove the balance shaft chain cover.
b. Remove the balance shaft chain guide.
c. Pull the housing to disconnect the pump gear from the balance shaft.
d. Remove the housing assembly from the balance shaft assembly.
e. Remove the oil pump bolts.
f. Remove the oil pump cover.
16. Balance Shaft and Housing Removal
a. Check the balance shaft end play prior to disassembling the balance shaft housing.
b. Set up the indicator to read off the back of the shafts.
c. Press against the: shafts and note their movement.
d. Compare the shafts against specifications.
e. If the shafts do not meet specifications, check the thrust plate for wear. Replace the thrust plate if it is worn.
f. If the end play does not meet specifications and the thrust plate is not worn, replace the balance shafts.
g. Remove the balance shaft chain cover.
h. Loosen but do not remove the balance shaft chain guide.
i. Use the camshaft sprocket wrench to hold the crankshaft.
CAUTION: The balance shaft driven sprocket bolt is left hand threaded and must be loosened by rotating it in a clockwise direction. If the bolt is not loosened in a clockwise direction, it may break.
j. Remove the balance shaft driven sprocket bolt.
NOTE: Mark the surface of the driven sprocket if it is going to be reused. This will insure that the chain continues to ride on the same tooth surface. Either surface can be placed against the shaft, if a new driven sprocket is installed.
k. Remove the driven sprocket from the shaft.
l. Remove the balance shaft assembly fasteners and remove the assembly to the bench.
m. Clean all of the balance shaft housing parts in cleaning solvent. Remove the varnish, sludge and dirt.
n. Inspect the housings for the following conditions:
^ Cracks
^ Scored bearing bores
^ Damaged threaded holes
NOTE: Replace the entire assembly if the housings are damaged in any way.
o. Clean all of the balance shaft chain cover parts in cleaning solvent. Remove the varnish, sludge and dirt.
p. Inspect the cover for the following conditions:
^ Cracks
^ Broken guides
^ Worn guides
17. Piston, Connecting Rod, and Bearing Removal
a. Rotate the crankshaft to a position where the connecting rod nuts are the most accessible.
b. Mark the connecting rod and cap with the cylinder position. Also mark their orientation. This will ensure the caps and connecting rods are re-assembled properly.
c. Remove any ridge at the top of the cylinder bore to avoid damage to the piston ring lands.
d. Remove the connecting rod nuts.
e. Remove the connecting rod cap.
f. Install thread protectors (3 in length of 3/8 inch I.D. hose) on the connecting rod bolts before removing the piston and connecting rod assembly.
g. Remove the piston and connecting rod assembly.
18. Crankshaft Rear Oil Seal and Housing Removal
a. Remove the seal housing to the block bolts.
b. Remove the oil seal housing.
c. Remove the gasket.
CAUTION: Properly support the seal housing to prevent damage to the seal during removal. Damage to the seal will result in an oil leak.
d. Use the following procedure in order to remove the oil seal:
^ Support the oil seal housing for oil seal removal using two wood blocks of equal thickness.
^ With the wood blocks on a flat surface, position the seal housing and the blocks in order for the transmission side of the oil seal housing to be supported across the dowel pin and the center bolt holes on both sides of the oil seal opening.
^ Drive the crankshaft seal evenly out of the transmission side of the oil seal housing. Use a small chisel in the relief grooves on the crankshaft side of the oil seal housing.
19. Crankshaft, Bearings, and Bearing Cap Removal
a. Remove the crankshaft position sensor. Inspect the position sensor for damage. Replace the sensor if necessary.
b. Remove the main bearing bolts.
c. Remove the bearing caps.
CAUTION: Remove the crankshaft carefully in order to avoid damaging the crankshaft journals, the rod, the main bearing inserts, or the connecting rods.
d. Remove the crankshaft from the block.
e. Remove the bearing inserts from the block.
f. Clean the oil, sludge, and carbon.
g. Inspect the oil passages for obstructions.
h. Inspect the keyway.
i. Inspect the threads.
j. Inspect the bearing journals and the thrust surfaces for the following conditions:
^ Cracks
^ Chips
^ Gouges
^ Roughness
^ Grooves
^ Overheating (discoloration)
k. Inspect the corresponding bearing inserts for imbedded foreign material. If foreign material exists find the cause and repair it.
NOTE: Replace the crankshaft if cracks, severe gouges or burned spots are found. Slight roughness may be removed with a fine polishing cloth soaked in clean engine oil. Burr may be removed with a fine oil stone.
l. Measure the crankshaft journals. Use a micrometer or dial indicator to measure the taper and runout. Note the result for the later selection of bearing inserts. If not within limits the crankshaft must be replaced.
CAUTION: Note the location of the main bearing high spots. If they are not in line, the crankshaft is bent and must be replaced.
20. Cylinder Block Plug Removal
a. Remove the cooling jacket drain plug.
b. Remove the oil gallery screw plugs.