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: 106,057 (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
68 people reported this problem
31 people shared problem details
2002 Pontiac Bonneville- 3.8L V676,000
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 V684,000
Intake manifold leaking oil.
2004 Pontiac Bonneville- 3.8L V690,000
Oil leak on top of engine from vale covers.
2005 Pontiac Bonneville- 3.8L V6137,500
Service engine light came on at 137500 miles. Car was diagnosed,will be fixed next week.
2002 Pontiac Bonneville- 3.8L V6132,890
Changed the plastic cover and the seal working good
2002 Pontiac Bonneville- 3.8L V6223,000
Loosing antifreeze from reservoir
2002 Pontiac Bonneville- 3.8L V6148,000
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.
Coolant was leaking, had the upper intake manifold 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!
1995 Pontiac Bonneville- 3.8L V6 Supercharged169,500
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 V655,000
Engine stalling and surging. Replaced intake manifold and cleaned throttle body and throttle position sensor (coolant had leaked onto TP sensor)
Lose in presure then cut off
2004 Pontiac Bonneville- 3.8L V680,000
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 V668,000
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 V682,000
Intake Manifold gasket leaks.
2005 Pontiac Bonneville- 3.8L V667,301
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 V6111,000
Leaking fluids. Took vehicle to Skinner and they diagnosed plastic manifold gaskets leaking.
2000 Pontiac Bonneville- 3.8L V6 Supercharged120,000
not fixed yet
2003 Pontiac Bonneville- 3.8L V6
Non-metallic manifold needed replacing. Mechanic said something similar about engine freezing due to leak. Cost is quoted around $500 parts & labor.
1995 Pontiac Bonneville- 3.8L V6
coolant leak, intake manifold
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