Mechanics

POSSIBLE HEAD GASKET PROBLEM

1999 Pontiac Bonneville

Engine Mechanical problem
1999 Pontiac Bonneville 6 cyl Front Wheel Drive Automatic 74000 miles

A month ago I had my entire cooling system flushed and the hoses replaced. A month I was having problem, the engine was running rough and when I got home I popped the hood and saw that all the antifreeze was gone. There was no sign of leakage. I leaked my oil and found no anti-freeze in the oil. I had to have the car towed back to the repair shop and they think that maybe it is either the head gasket or the intake manifold that needs to be replaced. What kind of money are we talking about here if this is the case?
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Pcstathis
January 11, 2009.



It's probably the intake, this is a very common problem. Some customers may comment on excessive engine coolant consumption, or an engine coolant leak near or under the throttle body area of the upper intake manifold.

Cause
Upper intake manifold composite material may degrade around the EGR stove pipe and could result in an internal or external coolant leak.

Correction
Follow the upper intake manifold removal instructions found in the Engine Unit Repair Section of the Service Information Manual.

Refer to the arrow in the illustration of the upper intake manifold above. Inspect the inner diameter of the EGR passage for signs of material degradation. Degradation will appear as " pitting" of the composite material in the EGR port passage.
If degradation of upper intake manifold composite material is found, replace the lower and upper intake manifolds with the following part numbers: • Gasket Kit, Upper Intake Manifold -- 89017554

• Manifold Kit, Upper Intake -- 89017272

• Gasket, Lower Intake Manifold -- 89017400

• Manifold, Lower Intake -- 24508923

Follow the lower and upper intake manifold installation instructions found in the Engine Unit Repair Section of the appropriate Service Manual.
If degradation is not apparent, skip to Step 7.
Verify the repair.
If no degradation is found, evaluate the vehicle for other causes of excessive coolant consumption as noted in the Engine Diagnosis Section of the appropriate Service Manual.
I would have them make sure first, replacing the upper/lower intake would be around $1000.00. Post back with any other questions.

Brian 1
Jan 11, 2009.