For 1990-2009 cars

# REVISED INTAKE MANIFOLD GASKETS

#### SUBJECT: REVISED INTAKE MANIFOLD GASKETS

#### VEHICLES AFFECTED: 1982-1988 CADILLACS WITH 4.1L AND 4.5L V8 ENGINES

Continuous development at Cadillac has resulted in an improved intake manifold gasket sealing system superseding the originally released gaskets. The sealing system is an engineered combination of components working together, and depending upon each other, to provide a durable, effective seal. The key components of the system are:

o New intake manifold side gaskets made of a graphite (rather than asbestos) based material.

o New manifold end seals with a grid of "suction cups" to aid sealability.

o New intake manifold attaching bolts with captured Belleville spring washers.

o New design stepped cylinder head guide pin (P/N 1634935) for service use on all 1982 through 1984 HT 4100 engines and 1985 HT 4100 engines built before engine #T10L499404. The stepped cylinder head guide pins replace the original slotted pins Figure 1 and must be installed whenever the cylinder heads are removed on these engines.

#### NOTE: The new design stepped pin may not be used in engines which use the tubular dowel pin.

#### Resealing Gasket Kits

These components have been assembled into a series of kits called "Intake Manifold Resealing Gasket Kits" with applications for all 1982-1988 4.1L and 4.5L V-8 engines.

P/N Application --- ------------ 3634741 1982-1983 C, E, K 3634742 1984 C, 1985 D, E, K 3634743 1985 C (FWD) 3634744 1986-1987 C, E, K 3634745 1987-1988 V 3634746 1988 C, E, K

These resealing units are intended for use when other engine service is being performed which requires cylinder head removal (i.e., it is necessary to install cylinder head dowels). Cylinder head removal to repair an intake gasket leak may make this kit uneconomical.

Each resealing kit contains detailed installation instructions including information on selection and position of spring/washer bolts and a revised bolt torquing procedure and new lower torque values required.

#### IMPORTANT: It is important to follow these instructions carefully to realize the maximum benefit from this new sealing system. It is likewise important that all resealing kit components be installed together.

#### Gasket Only Kits

For the most economical repair as well as to provide for subsequent service of engines already converted with resealing kits, a series of "gasket only" kits are also available.

These gasket kits are intended to directly replace the previously released gaskets described in P.S.B. 88-641-100. The kits contain only the new side gaskets and end seals and may be used with the conventional design intake manifold bolts. Specific installation instructions are again included and must be thoroughly followed.

P/N Application Replaces --- ----------- -------- 3634753 1982-1985 C, E, K, D 3634619 1986-1987 C, E, K 3634754 1987-1988 V 3634660 3634755 1988 C, E, K 3634723

Upgrading to the new sealing system provided by the resealing kits is preferred and recommended whenever repair economics permit. 1989 production engines as well as past model service engines produced after 1989 start of production will also incorporate the revised gaskets and bolts included in resealing kits.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.