Cylinder heads — removal and installation
Warning: Wait until the engine is completely cool before beginning this procedure.
Note: This procedure can only be done with the engine removed.
Removal
1. Relieve the fuel system pressure (see Fuel and exhaust systems), then disconnect the cable from the negative battery terminal (see Engine electrical systems).
2. Drain the cooling system (see Tune-up and routine maintenance).
3. Remove the engine.
4. Remove the intake manifold (s) (see Intake manifolds — removal and installation) and exhaust manifolds (see Exhaust manifolds — removal and installation) or turbochargers (see Fuel and exhaust systems).
5. Remove the valve covers (see Valve covers — removal and installation).
6. Remove the camshafts and lifters (see Camshafts and tappets/roller followers and lash adjusters — removal, inspection and installation).
7. Remove the drivebelt and the drivebelt tensioner (see Tune-up and routine maintenance).
8. Remove the two Camshaft Position (CMP) sensors at the rear of each cylinder
head. Disconnect any other electrical connectors from the cylinder head and mark them with tape for correct reassembly.
9. Loosen the cylinder head bolts in 1/4- turn increments until they can be removed by hand. Work from bolt-to-bolt in the reverse of the tightening sequence (see illustrations 11.18a or 11.18b).
Note: Remove the bolts and discard them -new bolts must be used when installing the cylinder head (s).
10. Lift the cylinder head (s) off the engine. If resistance is felt, DO NOT pry between the cylinder head and engine block as damage to the mating surfaces will result. To dislodge the cylinder head, place a wood block against the end of it and strike the wood block with a hammer or pry against a casting protrusion. Store the cylinder heads on blocks of wood to prevent damage to the gasket sealing surfaces.
11. Cylinder head disassembly and inspection procedures should be performed by a qualified automotive machine shop.
Installation
12. The mating surfaces of the cylinder heads and engine block must be perfectly clean when the cylinder heads are installed. Cover all openings with shop rags to keep debris out of the engine. Use a vacuum cleaner to remove any debris that falls into the valley or intake ports.
Caution: Do not use a scraper of any kind or abrasive discs to remove old gasket material, as the block, heads and intake manifold (s) are aluminum.
13. Check the engine block and cylinder head mating surfaces for nicks, deep scratches and other damage. If damage is slight, it can be removed with a file — if it’s excessive, machining may be the only alternative. Use a straightedge and feeler gauges to check for warpage (see illustration). If the warpage is beyond Specifications, have the head machined at an automotive machine shop.
11.13 Check the cylinder head and block surfaces for flatness with a straightedge
14. Use a tap of the correct size to chase the threads in the block head bolt holes. Dirt, corrosion, sealant and damaged threads will affect torque readings.
15. Position the new gasket (s) over the dowel pins in the engine block. Make sure it’s facing the right way. If the cylinder head is to be replaced, a new secondary timing chain tensioner will be required.
16. Carefully position the cylinder head (s) on the engine block without disturbing the gasket(s).
17. Lightly oil the new cylinder head bolts and turn down by hand until snug.
Caution: The cylinder head bolts are the torque to-yield type and are stretched during tightening. Therefore, the original bolts must be discarded and new bolts installed during assembly.
18. Tighten the bolts, in the recommended sequence, to the torque and angle of rotation listed in this Chapter’s Specifications (see illustrations).
11.18a Cylinder head bolt tightening sequence
11.18b An angle gauge takes the guesswork out of tightening the torque-to-yield cylinder head bolts
Note: The method used for the cylinder head bolt tightening procedure is referred to as the «torque angle» or «torque-to-yield» method; follow the procedure exactly. Tighten the bolts using a torque wrench, then use a breaker bar and a special torque angle adapter (available at auto parts stores) to tighten the bolts the required angle.
19. The remainder of installation is the reverse of removal.
20. Change the engine oil and filter and refill the cooling system (see Tune-up and routine maintenance), then start the engine and check carefully for oil and coolant leaks.