How to fix Leaking intake manifold gaskets on GM engines
GM 3.1 and 3.4-liter engines are known for leaking intake manifold gaskets. If you replace the gaskets yourself, there are a few tips and warnings to be aware of.
You’ll have to remove the push rods to lift off the intake manifold. The intake and exhaust push rods are different sizes, so PAY attention to the order in which you remove them. Get a cardboard box and poke holes in it. Insert the push rods into the holes in the exact order you removed them. And make sure you place them back into the engine in the exact locations they came from. Not only that, but keep track of the top and bottom of each push rod. As the engine wears, the push rods, rocker arms, and lifters all develop unique wear patterns. If you swap a push rod with another location, you WILL get noise when re-assembling the engine.
If you mix up the push rods, here’s how to sort them. Intake push rods have a yellow stripe and 5-3/4″ long. Exhaust push rods have green stripes and are 6″ long.
There’s an easy way to remove and replace the push rods with a special tool from Lisle tools. This tool compresses the valve spring and allows you to remove the push rod and replace it WITHOUT loosening the rocker arm. That’ll take at least 1-full hour off the repair. Click here to see or buy the tool. The tools is worth every penny.
This is an aluminum alloy engine, so be very careful when cleaning all gasket surfaces. Never (and I mean never) use a metal scraper to remove corrosion or old RTV sealant. Use a plastic scraper.
Use the recommended GM RTV sealant. GM isn’t kidding about this. It’s worth a trip to the dealer to not have to do this repair a second time.
ALWAYS use new intake manifold bolts and follow the torque procedure to the letter. These are plastics intake manifold gaskets and you WILL have a leak if you don’t use new bolts and if you don’t torque them exactly according to procedure
© 2012 Rick MuscoplatPosted on by Rick Muscoplat