Skylark L4-138 2.3L DOHC VIN D MFI QUAD 4 (1989)
Cylinder Head Gasket: All Technical Service Bulletins
Service Procedure
The following procedure supplements the existing service manual procedure. The tightening sequence replaces all 1988-91 service manual head
tightening procedures for Quad 4 engines.
1.
Completely drain the cooling system and properly dispose of the coolant. Do NOT recycle coolant from this engine.
NOTICE:
The cylinder block, head, radiator and heater core must be completely drained of coolant since the old coolant will be contaminated with
combustion residue. Refer to the appropriate section of your service manual.
2.
Remove the cylinder head. Refer to the appropriate service manual section.
3.
Inspect the timing chain tensioner shoe (1990 and earlier vehicles). If the tensioner shoe has grooves worn into it in excess of 1.14 mm (0.045 in.)
deep from the chain, replace the tensioner shoe and stud with GM P/N 12340864 (see Figure 1).
NOTICE:
On 1989 vehicles, also check the thickness of the backing plate (see Figure 1). If the thickness is 2 m (0.079 in.), replace the tensioner shoe and
stud with GM P/N 12340864. The new tensioner shoe backing plate will be 3.7 mm (0.146 in.) thick.
4.
Inspect the head bolts for damaged threads or for damaged bolt heads caused by improper use of tools. Replace head bolts if necessary.
5.
Inspect the cylinder head surface for corrosion or cracks. The fire rings will leave a "shadow" mark on the cylinder head (shaded area - Figure 2).
If any corrosion is visible within this shaded area and/or if cracks are found, the cylinder head should be replaced.
If corrosion is evident outside of the outside diameter (OD) of the fire rings (shaded area - Figure 2), the cylinder head may be re-used.
6.
Thoroughly clean the cylinder head and block surfaces. Check the cylinder head surface for flatness.
NOTICE:
Use only a plastic or wood scraper. Use extreme care so the sealing surface is not scratched. Do not use any other method or technique to remove
gasket material.
A.
Carefully remove all gasket material. Use Chisel Gasket Remover, Loctite Item # 79040, Permatex Gasket Remover (# 4M4), or equivalent.
B.
Check cylinder head for flatness. Refer to service manual section 6A7 for cylinder head checking procedure and specifications.
