GMC 12554258 Pan Assembly, Oil

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In order to remove and install the oil pan, the procedure is different for each model year as well as the drivetrain. To start with 1994 and 1995 4WD models, you should disconnect negative battery cable and drain oil. Starter motor needs to be removed as well as two engine-to-bellhousing braces and lower part of bellhousing cover. Exhaust pipes must be separated from the manifolds. Oil pan mounting bolts/nuts are removed carefully noting location of studs and brackets. Slowly separate pan from block without prying so as not to damage sealing surfaces. Sealing surface distortion on oil pan flange can also be checked if any. New gasket is attached to pan with RTV sealant applied after cleaning gasket surfaces and carefully positioning it against block. Bolts/nuts are tightened in three steps starting at center and following a spiral pattern outwards. Engine removal may be needed for 2WD models (especially those with cast-aluminum oil pans) while 4WD models can use raised engine, which could mean that they will need to remove the engine first before accessing it fully in case there is a cast-aluminum oil pan involved. After removing bolts separate the pan carefully without using a pry tool, clean gasket surfaces, apply RTV sealant. Aligning the pan properly with the block, checking clearances when necessary then tightening of the bolts/studs holding it down in sequence. Complete remaining steps in reverse order; start engine; check for leakages at the pan before engaging gear.

If the oil pan is stuck, it can be dislodged using a block of wood and a hammer.

A scraper should be used to remove all traces of sealant from the pan and block. The mating surfaces should then be cleaned with lacquer thinner or acetone.

The oil pan mounting bolts/nuts should be removed, and it's important to note the location of studs and brackets to ensure proper reinstallation during assembly.

If the oil pan is stuck, it can be dislodged using a block of wood and a hammer.

A thin coat of RTV sealant should be applied to the ends of the rubber seal, where it fits into the main bearing cap.

After completing the oil pan installation process, clearances should be measured as needed, and the engine should be started to check for oil leaks at the oil pan.