The Chevy 3.1 L engine as well as the Chevy 3.4 L engine that use Dex Cool Anti-freeze are known for lower intake manifold gasket leaks. Pressure testing the coolant system can usually confirm if your lower intake manifold is leaking or not. If it leaking, you will want to replace it right away to prevent further damage. There are complete instruction below for replacing the lower intake manifold gasket on your 3.1 L engine.
NOTE: Make sure the gasket and seal surfaces are clean.
|Lower intake manifold bolt installation
Manufacturer recommends the center bolts be fully torqued before the diagonal bolts to assure proper sealing. The lower intake manifold bolts in location 6 and 7 should be torqued to specification using a crows foot type tool.