Jim Grant's Tech Tips

'98 Pontiac Grandprix, Intake Trouble

Q: Two days ago I changed both lower intake gaskets on my ‘98 Pontiac Grandprix 3.8 with 86k. The driver’s side was leaking antifreeze. After I reinstalled everything. I started my vehicle and it ran fine and sounded good too. But when I pulled the oil cap off while it was running to check for any internal anti freeze leaks, the car had a high vacuum pressure as if it didn’t want the cap to come off. The same thing happened when I pulled the dip stick too. The engine’s idle changed, the car started purging for air, then when I drove it gave off this loud awful screeching sound, off and on while driving............please tell me what you think it could be....desperate!

A: I would suggest going back down to the parts store and picking up another intake manifold gasket set and get set-up to change the intake gasket set again. Why? Either you damaged or incorrectly installed the gasket. Having such a great volume of engine vacuum in the crankcase is a sure sign of an internal leak. The intake manifold gasket on your vehicle’s engine seals the intake passages. If there is a leak due to damage or use of the incorrect gaskets a vacuum leak will occur. In your case the leak is into the internals of the engine. Don’t drive your vehicle under this condition. Having a vacuum leak of that size into the engine will cause oil consumption and could damage other gaskets and seals.