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For 1990-2009 cars only
Makes 🢒 Buick 🢒 1983 🢒 Skylark 🢒 Bulletins 🢒 THERMOSTAT HOUSING RESEALING PROCEDURE

THERMOSTAT HOUSING RESEALING PROCEDURE

MODELS AFFECTED: 1983 SKYLARK WITH 2.5L L-4 ENGINES (VIN CODE R)

The sealing material for the thermostat housing to cylinder head mating surfaces was changed from liquid RTV to a thermally cured silicone rubber known as LIM (Liquid Injection Mold). The new material (red in color) is applied to the thermostat housing and cured by heating to 400 DEG F before installing the housing to the engine.

The compression resistance of the cured seal material causes some deformation of the housing to cylinder head mounting flange during assembly. The flange deformation does not hurt the sealing ability of the original LIM, but it may make it difficult to satisfactorily reseal the housing with conventional RTV or service gasket. The degree of difficulty of resealing a steel housing that was originally sealed with LIM, will be dependent upon the magnitude of deformation, which is a function of production variables, amount and hardness of LIM.

It is therefore recommended, that one of the following methods be used to reseal the thermostat housing to cylinder head on engines built with LIM seal:

1. If LIM is still attached to housing and in good condition, clean housing with solvent, air dry, apply a film of conventional RTV on top of LIM, and reinstall housing.

2. Install new thermostat housing (part number 10026520) and seal with conventional RTV or gasket.

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