1997 Buick Lesabre carpro tech, question

The coolant in the intake is from the EGR passage being rotten, letting coolant into the upper plenum. If you remove the upper and turn it over, you will see it rotten where the EGR gasses go through it. Common for those engines

Hi Jack
Yes you are exactly right. The funny thing is I removed the plantum and dissassembled, and shined a light inside exhaust port. But was unable to find the leak. However after reading your post I checked again and just minor pressure with a ink pen revealed
pin hole. Anyway I really appriciate your help.

Billymac

Anytime. Funny thing is I had the exact same thing on the rack at the same time. Quite a coincidince

This was a common problem on these, had alot of these. Replace the upper and lower intake, not just the gaskets, but the actual intake upper and lower. There is an updated intake and plentum. What happens is the egr port under the plentum is to big and burns the intake port and causes coolant to leak into the egr port and into the engine. Here is the bulletin, 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:
"Â Gasket Kit, Upper Intake Manifold -- 89017554

"Â Manifold Kit, Upper Intake -- 89017272

"Â Gasket, Lower Intake Manifold -- 89017400

"Â 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.