Intake Manifold Gaskets Can Develop Engine Oil Leaks on Pontiac Bonneville

Problem Description and Possible Solution

The intake manifold gaskets can develop external engine oil or coolant leaks. The intake manifold will need to be removed and the gaskets replaced to correct this issue. In some cases the plastic intake manifold my be damaged requiring replacement.

Problem Data
RepairPal Verified
Average mileage: 108,076 (34,000–223,000)
Engines affected: 3.8L V6, 3.8L V6 Supercharged
16 model years affected: 1990, 1991, 1992, 1993, more1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
76 people reported this problem
Viewing 1 - 20 of 33 comments
Noticed antifreeze level kept dropping. Would only see tiny amount on driveway not enough to explain amount being lost. Checked hoses, radiator, antifreeze holding tank no obvious leaks. noticed moisture on inside of oil fill cap. Went for annual inspection, mechanic found where antifreeze was leaking at top of engine and running onto exhaust burning most of it up before hitting the ground. Found upper and lower intake gaskets leaking. Replaced both
Lowqer intake manifold gaskets failed. Replaced with FelPro MS 98014 T. Upper intake manifold (Plenum) failed EGR tube. Replaced with Dorman 615-180.
Slight loss of coolant (but no visible external signs). Recent issues with engine "bucking" when warmed up. Diagnosed at shop, will have gasket (s) replaced.
& again @ 105000! twice now sick of paying for this! thinking GM should be paying for it with all the issues with the 3.8L. and battery under back seat ate through seatbelt housing!
The engine leaks oil, not badly and not all the time. Just now and again it will leak. Enough to notice some days.
Engine stalling and surging. Replaced intake manifold and cleaned throttle body and throttle position sensor (coolant had leaked onto TP sensor)
I have had a slight oil leak for quite a while, and it seems to correlate with this common problem.
Noticed sweet smell at first, then burnt oil on engine block. Rough idle, white smoke out of exhaust. No milky oil though yet. Hoping to get it fixed next week.