Question about 1994 GMC Sierra

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Replaced rear main seal on 5.7 but still seems to be leaking. Any suggestions?

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Be sure it is the rear main seal,there is a cam plug that could be leaking,but if it is the rear main oil seal leaking,then I suggest removing it,and installing a rear main repair sleeve,this will give it a new surface to ride on,the crankshaft may have a groove cut into it from the oil seal,this will remedy the problem.If this was at all helpful,please rate,thank you.

Posted on Jul 10, 2010

  • wolds99 Jul 19, 2010

    where is this elusive cam plug?

  • Ronny Bennett Sr.
    Ronny Bennett Sr. Jul 19, 2010

    The cam plug is up above the crank shaft seal.



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    I have had my rear main seal replaced 3 times and it is still leaking. Could this leak be coming from somewhere else? The first mechanic assumed it was the rear main seal, and the others I informed them...

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    Is the fluid leak indeed oil (black/brown)? If so that would be the rear main. Problem could be the surface around the seal on the engine has a defect or space.

    If the fluid leak is a reddish color this is transmission fluid and would be the torque convertor leaking not the rear main.

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    88143g59.gif Crankshaft rear main seal - 5.7L engine

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    88143g60.gif Exploded view of the rear main seal installation - 3.4L engine
    Click to Enlarge

    1. Tighten the wing nut on the installation tool until it bottoms out.
    2. Remove the tool from the crankshaft or rear oil seal housing, as applicable.
    88143g61.gif Rear main seal and installation tool - 3.8L engine
    Click to Enlarge
    88143g62.gif After position the seal on the tool, install it to the crankshaft housing

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