REMOVAL & INSTALLATION
See Figures 1 and 2
- Disconnect the negative battery cable for safety.
- Drain the cooling system and relieve the fuel system pressure.
- Remove the air cleaner.
Before removing the spark plug wires, check the configuration of your engine against the firing order diagrams found in Engine Electrical in this repair guide. If your engine is different in any way, make notations to the diagrams to assure proper installation. Also, be sure to tag all of the spark plug wires and the distributor cap or ignition coil pack terminals, as applicable.
- Tag and remove the spark plug wires, then remove the spark plugs.
- On the distributor equipped (VIN A) engine, remove the heater hose retaining screw from the rocker arm cover, then matchmark and remove the distributor assembly.
- On the distributorless (VIN M) engine, tag and disconnect the engine and alternator harnesses.
- Tag and disconnect the required vacuum hoses.
- Remove the dipstick. On the distributorless (VIN M) engine, disconnect the dipstick tube from the bracket.
- Remove the upper intake manifold and throttle body assembly (along with the EGR tube on distributorless VIN M engines). For details, please refer to the intake manifold procedure in this section and the throttle body procedure found in Fuel System of this repair guide.
- Remove the lower intake manifold assembly from the cylinder head.
- For the distributor equipped (VIN A) engine, remove the dipstick retaining bolt from the intake manifold.
- Remove the rocker arm cover from the cylinder head.
- For the distributorless (VIN M) engine, remove the belt tensioner, then loosen the alternator retaining bolt and swing the alternator aside. Remove the ribbed accessory drive belt.
- Disconnect the upper radiator hose at both ends, then remove it from the vehicle.
- Remove the timing belt cover retaining bolt(s) and remove the cover.
- Loosen the timing belt idler retaining bolts. Position the idler in the unloaded position and tighten the retaining bolts.
- Remove the timing belt from the camshaft pulley and the auxiliary pulley. Refer to the information on Timing Belts in General Information & Maintenance of this repair guide to decide if the belt should be replaced. If the belt is not going to be replaced, be sure to mark the current direction of rotation on the belt to assure proper installation.
- Remove the 8 exhaust manifold retaining bolts, then remove the manifold from the cylinder head.
- Remove the timing belt idler and two bracket bolts. Remove the timing belt idler spring stop from the cylinder head.
- On the distributor equipped (VIN A) engine, disconnect the oil sending unit wire.
- Remove the cylinder head bolts, then break the gasket seal and remove the cylinder head.
- Clean all gasket mating surfaces and blow the oil out of the cylinder head bolt block holes.
- Check the cylinder head for flatness using a straightedge and a feeler gauge. If the head gasket surface is warped greater than 0.006 in. (0.152mm), it must be resurfaced. Do not grind off more than 0.010 in. (0.254mm) from the cylinder head.
- Position a new cylinder head gasket on the engine. Rotate the camshaft so that the locating pin is approximately 30 degrees to the right of the 6 o' clock position when facing the front of the cylinder head (this places the pin about at the five o'clock position) to avoid damage to the valves and pistons.
- If they are available, cut the heads off of two old cylinder head bolts to use as guide studs. Thread the studs into the
engine block at opposite corners to use as guides.
- Make sure the gasket is properly fit to the block, then set the head into place. Apply a non-hardening gasket sealer to the bolt threads and install the bolts finger-tight.
- For 1989-92 vehicles, tighten the head bolts using 2 passes of the sequence, first to 50-60 ft. lbs. (68-81 Nm) and then to 80-90 ft. lbs. (108-122 Nm).
- For 1993 vehicles, tighten the cylinder head bolts in 2 passes of the sequence to 52 ft. lbs. (70 Nm) and retighten to 52 ft. lbs. (70 Nm). Then, tighten the bolts an additional 90° plus or minus 10° in a third pass of the sequence. Although a torque angle meter is the best way to angle tighten bolts, you can get satisfactory results by painting or marking a line on the socket and watching it until a 1 / 4 turn has been achieved.
- On the distributor equipped (VIN A) engine, connect the oil sending unit wire.
- Install the timing belt tensioner spring stop to the cylinder head.
- Position the timing belt tensioner and tensioner spring to the cylinder head and install the retaining bolts. Rotate the tensioner against the spring with belt tensioner tool T74P-6254-A, or equivalent, and temporarily tighten.
- Install the exhaust manifold using the 8 retaining bolts and a new gasket. For details, please refer to the Exhaust Manifold procedure found earlier in this section.
- If equipped with a distributor, align the distributor rotor with the No. 1 plug location on the distributor cap and install.
- Align the camshaft sprocket with the pointer and align the crankshaft pulley with the pointer on the timing belt cover.
- Install the timing belt over the sprockets. If the belt is not being replaced, make sure you have installed it in the same direction of rotation as it was before removal.
- Complete timing belt installation as detailed under the timing belt procedures located later in this section. Be sure to check belt tension and alignment, then to properly tighten the tensioner and pivot bolts.
- Install the timing belt cover and tighten the retaining bolt(s) to 6-9 ft. lbs. (8-12 Nm).
- Install the rocker arm cover and tighten the retaining bolts to 62-71 inch lbs. (7-11 Nm).
- Install the lower intake manifold assembly. Tighten the bolts, in sequence, to 20-29 ft. lbs. (26-38 Nm).
- Install the upper intake manifold and throttle body (along with the EGR tube assembly on VIN M engines). Tighten the upper intake-to-lower intake bolts to 15-22 ft. lbs. (20-30 Nm).
- Install the upper radiator hose.
- Connect the vacuum hoses as tagged during removal.
- If removed, install the belt tensioner.
- Position the alternator and install the drive belt.
- Install the dipstick and, if applicable, secure the dipstick tube to the intake manifold using the retaining bolt.
- On distributor equipped (VIN A) engines, install the distributor cap.
- Install the spark plugs, then install the spark plug wires as tagged and noted during removal. Remember, that if your engine wiring didn't agree with the firing orders in Engine Electrical , you should not try to make it agree now.
- If not already installed, position and connect the engine and alternator wiring harnesses.
- If equipped, install the heater hose retaining screw to the rocker arm cover.
- Install the hose from the air cleaner to the throttle body.
- Connect the negative battery cable, then fill and bleed the cooling system.
- Bring the engine to normal operating temperature and check for leaks.
- If equipped with distributor ignition, check the ignition timing.
See Figures 3 through 11
If the left cylinder head is being removed on vehicles equipped with A/C, the refrigerant system must be discharged and recovered using a suitable recovery station prior to starting the procedure. If you do not have the proper certification and access to the necessary equipment, take the vehicle to a service station and have the A/C system discharged before proceeding.
- Disconnect the negative battery cable for safety.
- Drain the cooling system and properly relieve the fuel system pressure.
- Remove the upper and lower intake manifold assemblies, along with the throttle body. For details, please refer to the intake manifold procedures found earlier in this section.
If you are removing the left cylinder head:
- On vehicles equipped with A/C, properly discharge and recover the refrigerant from the air conditioning system, then remove the compressor.***WARNING***Immediately cap or plug all openings to the air conditioning system in order to prevent system contamination and damage.
- If not done earlier, remove the drive belt from the power steering pump pulley, then disconnect the power steering pump bracket from the cylinder head. Position the pump out of the way in a position that will prevent the oil from draining out.
- Disconnect the oil level indicator tube bracket from the exhaust manifold stud, if necessary.
- Remove the Thermactor/secondary air injection crossover tube from the rear of the cylinder heads.
If you are removing the right cylinder head:
- Disconnect the alternator or alternator and air pump mounting bracket from the cylinder head, as equipped.
- Remove the fuel line from the clip at the front of the cylinder head.
- Raise and support the vehicle safely using jackstands. Disconnect the exhaust manifolds from the muffler inlet pipes, then remove the jackstands and carefully lower the vehicle.
- Loosen the rocker arm fulcrum bolts so the rocker arms can be rotated to the side. Remove the pushrods and tag or arrange them in sequence so they may be installed in their original positions.
A piece of wood or cardboard may be drilled and labelled to help sort the pushrods and make sure they are only installed to the rocker arms and lifters from which they were removed.
- Remove the cylinder head attaching bolts and the cylinder heads.Remove and discard the head gaskets.
It may be necessary to remove the exhaust manifolds for access to the lower head bolts. If so, be sure to thoroughly clean the gasket mating surfaces and to use new exhaust manifold gaskets upon installation.
- Clean all gasket mating surfaces. Check the flatness of the cylinder head using a straightedge and a feeler gauge. The cylinder head must not be warped any more than 0.003 in. (0.076mm) in any 6 in. (152mm) span; 0.006 in. (0.152mm) overall. Machine if necessary. For details, please refer to the cylinder head inspection and refinishing procedures in this section.
- Position the new cylinder head gasket over the dowels on the block. Position the cylinder heads on the block and install the head bolts.
- For 1989-92 vehicles tighten the bolts, using 2 steps of the proper sequence. First tighten the bolts to 55-65 ft. lbs. (75-88 Nm), then to 65-72 ft. lbs. (88-98 Nm).
When the cylinder head bolts have been tightened following these procedures, it is not necessary (but it is permissible, if desired) to retighten the bolts after extended operation.
- On 1993 vehicles, determine what type of head bolts are used in your engine. Standard non-flanged head bolts should be tightened using the same 2 steps and values as 1989-92 vehicles. Flanged hex head bolts should be tightened in three steps of the proper sequence. Start by tightening the bolts to 25-35 ft. lbs. (34-47 Nm), then tighten the bolts to 45-55 ft. lbs. (61-75 Nm). Finally, tighten all bolts an additional 1 / 4 turn (85-95° if a torque angle meter is available).
- If removed, install the exhaust manifolds using new gaskets.
- Clean the pushrods, making sure the oil passages are clean. If you have access to compressed air, blow out the passages to be sure they are clear. Check the ends of the pushrods for wear. Visually check the pushrods for straightness or check for run-out using a dial indicator. Replace pushrods, as necessary.
- Apply a suitable multi-purpose grease to the ends of the pushrods and install them in their original positions. Position the rocker arms over the pushrods and the valves.
If all the original valve train parts are reinstalled and no cylinder head milling was performed, a valve clearance check is not necessary. If any valve train components are replaced, a valve clearance check must be performed.
- Raise and support the vehicle safely using jackstands. Connect the exhaust manifolds to the muffler inlet pipes, then remove the jackstands and carefully lower the vehicle.
- If the right cylinder head was removed, reposition and install the alternator, or alternator and air pump bracket. Install the alternator assembly.
- Install rocker arm covers using new gaskets.
- If the left cylinder head was removed, reposition and install the A/C compressor and/or the power steering pump, as equipped.
- Install the drive belt, making sure that the belt tensioner is maintaining the proper tension and that the belt is properly aligned on all of the pulleys.
- Install the Thermactor/secondary air injection crossover tube at the rear of the cylinder heads.
- Install the upper and lower intake manifold assemblies.
- Connect the negative battery cable, then fill and bleed the cooling system.
- Bring to normal operating temperature. Check for leaks. Check all fluid levels.
- If the A/C system was discharged, take the vehicle is a reputable service facility and have the refrigerant system leak-tested, evacuated and charged according to the proper procedures.
CLEANING AND INSPECTION
See Figures 12, 13 and 14
- With the valves installed to protect the valve seats, remove deposits from the combustion chambers and valve heads with a scraper and a wire brush. Be careful not to damage the cylinder head gasket surface. After the valves are removed, clean the valve guide bores with a valve guide cleaning tool. Using cleaning solvent to remove dirt, grease and other deposits, clean all bolts holes and be sure that all oil passages are.
- Remove all deposits from the valves with a fine wire brush or buffing wheel.
- Inspect the cylinder heads for cracks or excessively burned areas in the exhaust outlet ports.
- Check the cylinder head gasket surfaces for cracks, burrs and nicks. Although burrs or nicks in this area can be dressed down using an oilstone, you should replace a head if it is cracked.
- On cylinder heads that incorporate valve seat inserts, check the inserts for excessive wear, cracks, or looseness.
- If the cylinder head was removed to replace a blown head gasket, be sure to check the head for flatness and to determine if resurfacing is necessary.
Cylinder Head Flatness
See Figures 15, 16 and 17
When the cylinder head is removed, check the flatness of the cylinder head gasket surfaces. This is especially important if a head gasket was blown and cylinder head warpage is suspected.
- Place a straightedge across the gasket surface of the cylinder head. Using feeler gauges, determine the clearance at the center of the straightedge.
- If warpage exceeds 0.003 in. (0.076mm) in a 6 in. (152mm) span, or 0.006 in. (0.152mm) over the total length, the cylinder head must be resurfaced.
- If necessary to refinish the cylinder head gasket surface, do not plane or grind off more than 0.254mm (0.010 in.) from the original gasket surface.
When milling the cylinder heads of V8 engines, the intake manifold mounting position is altered, and must be corrected by milling the manifold flange a proportionate amount. Consult an experienced machinist about this.