Intake Manifold Gaskets Can Develop Engine Oil Leaks on Pontiac Bonneville

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.

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Average mileage: 108,602 (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
70 people reported this problem
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Viewing 1 - 20 of 32 problem details
2002 Pontiac Bonneville - 3.8L V6 76,000 mi,
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
2002 Pontiac Bonneville - 3.8L V6 84,000 mi,
Intake manifold leaking oil.
2004 Pontiac Bonneville - 3.8L V6 90,000 mi,
Oil leak on top of engine from vale covers.
2002 Pontiac Bonneville - 3.8L V6 223,000 mi,
Loosing antifreeze from reservoir
2005 Pontiac Bonneville - 3.8L V6 137,500 mi,
Service engine light came on at 137500 miles. Car was diagnosed,will be fixed next week.
1997 Pontiac Bonneville - 3.8L V6 97,000 mi,
Coolant was leaking, had the upper intake manifold replaced
Lose in presure then cut off
2002 Pontiac Bonneville - 3.8L V6 132,890 mi,
Changed the plastic cover and the seal working good
2002 Pontiac Bonneville - 3.8L V6 148,000 mi,
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.
1998 Pontiac Bonneville 207,000 mi,
Intake manifold leaking oil. Replacing manifold and gaskets
2002 Pontiac Bonneville 90,000 mi,
& 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!
1995 Pontiac Bonneville - 3.8L V6 Supercharged 169,500 mi,
The engine leaks oil, not badly and not all the time. Just now and again it will leak. Enough to notice some days.
2003 Pontiac Bonneville - 3.8L V6 55,000 mi,
Engine stalling and surging. Replaced intake manifold and cleaned throttle body and throttle position sensor (coolant had leaked onto TP sensor)
2004 Pontiac Bonneville - 3.8L V6 80,000 mi,
I have had a slight oil leak for quite a while, and it seems to correlate with this common problem.
2003 Pontiac Bonneville - 3.8L V6 68,000 mi,
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.
2003 Pontiac Bonneville - 3.8L V6 82,000 mi,
Intake Manifold gasket leaks.
2005 Pontiac Bonneville - 3.8L V6 67,301 mi,
Lowqer intake manifold gaskets failed. Replaced with FelPro MS 98014 T. Upper intake manifold (Plenum) failed EGR tube. Replaced with Dorman 615-180.
2001 Pontiac Bonneville - 3.8L V6 111,000 mi,
Leaking fluids. Took vehicle to Skinner and they diagnosed plastic manifold gaskets leaking.
2000 Pontiac Bonneville - 3.8L V6 Supercharged 120,000 mi,
not fixed yet
Non-metallic manifold needed replacing. Mechanic said something similar about engine freezing due to leak. Cost is quoted around $500 parts & labor.