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.Google+
Car Problem Reports
Pontiac Bonneville Intake Manifold Gaskets Can Develop Engine Oil Leaks
Pontiac Bonneville Problem
Engines Affected: 3.8L V6, 3.8L V6 Supercharged
Average Mileage: 105,493 mi (34,000 mi - 196,000 mi)
Visitor, 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.
Visitor, 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.
Visitor, 2002 Pontiac Bonneville, 3.8L V6, 84,000 mi
Intake manifold leaking oil.
Visitor, 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
Coolant was leaking, had the upper intake manifold replaced
Visitor, 2004 Pontiac Bonneville, 3.8L V6, 90,000 mi
Oil leak on top of engine from vale covers.
Visitor, 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.
Visitor, 2001 Pontiac Bonneville, 3.8L V6, 111,000 mi
Leaking fluids. Took vehicle to Skinner and they diagnosed plastic manifold gaskets leaking.
Visitor, 2000 Pontiac Bonneville, 3.8L V6 Supercharged, 120,000 mi
not fixed yet
Visitor, 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.