Cylinder Heads - Updated Parts/Servicing
Group Ref.: EngineBulletin No.: 476101
Date: February, 1994
INFORMATION
SUBJECT:
SERVICING 2.0L AND 2.2L OHV CYLINDER HEADS WITH 7 MM VALVE GUIDE PARTIAL CYLINDER HEAD ASSEMBLY
MODELS:
1994 BUICK CENTURY
1987-94 CHEVROLET CAVALIER, BERETTA AND CORSICA
1994 OLDSMOBILE CUTLASS CIERA
1994 CHEVROLET AND GMC S TRUCKS
1987 - 1994 cylinder heads will now be serviced with a partial cylinder head assembly using 7 mm valve guides. The service cylinder head partial assembly will include all the valves (7 mm valve stems), valve springs, valve keepers, valve spring caps, seals and seats.
The 1987 - 1993 production cylinder heads use an 8mm valve guide. The 1987 - 1993 model year cylinder heads will now be serviced with 7 mm valve guide cylinder heads. Additionally, the intake valve seat on the 1987 - 1991 applications was 43 mm (1.69"). The new service cylinder head has 44 mm (1.73") intake valve seats. The 7 mm valve train components listed above cannot be used on a cylinder head with 8 mm valve guides.
Technicians will have to transfer the rocker arms, rocker arm ball, rocker arm stud and nut, and push rod guide from the old head to the new cylinder head.
A cylinder head core hole plug will be included in the parts kit. The core plug will only be used on car applications. DO NOT USE THE CORE PLUG ON TRUCK APPLICATIONS. Refer to Figure 1.
1987 - 1991 applications do not use a temperature sensor in the location indicated in Figure 2; install the 1/8 x 27 plug included in the kit.
If the new 7 mm valve guide head has been put on a past model engine, it can be identified by the casting number. The heads with 7 mm valve guide will have an "S" following the 8 digit casting number. All other 2.0L OHV and 2.2L OHV cylinder heads only have the 8 digit casting number. This number will be located in the rocker arm valley under the valve rocker arm cover.
Use the 1994 parts book to order valve train and cylinder head components for any 2.0L/2.2L cylinder head that has an "S" after the casting number. Use the applicable 1994 Service Manual for specifications and service procedures.
Starting January 1994, cylinder heads will be produced so the valve stem seals for the intake and exhaust will be the same. Use the intake seal part number.
If a cylinder head with 7 mm valve guide is on the engine, the 8 mm valve guide reamers (J 38847, J 38848 and J 38849) MUST NOT BE USED. There will only be one oversized valve available for the 7 mm valve guides. A new reamer, J 38978, must be used to obtain the .127 mm oversize.
PARTS INFORMATION:
Before ordering part, check availability of engine assembly through currently published engine exchange programs.
Cylinder Head, Partial Assembly
1987 - 1991 24574841
1992 - 1994 24574842
WARRANTY INFORMATION:
For vehicles repaired under warranty, use:
Labor Operation: J0518 - Head, Cylinder - Replace
Labor Time: Use published labor operation time.