Thread: 97 Grand Prix Se 3 leaking seals and Dexcool..?

I for sure have compromised intake manifold gaskets, and I suspect the gaskets under both valve covers are leaky as well. I'm not talking major leaks, but I've seen this before: moist spots and oil accumulation around each of these gasket areas.

Engine runs ok, but is acting rather like it has a vacuum leak. I've put about 1200 miles on this car since I bought it, bringing it to 160,000 miles. Compared to the 93 Ford Taurus and 94 Ford Escort I've owned, this car is in much better shape, even though the Escort was invincible. But, neither of those cars ever had leaking gasket problems after 150,000 miles, or the kind of dark brown residue I'm seeing under the Grand Prix's oil cap, in PCV valve, etc...

Now don't get me wrong, I love this car and I love GM but I want to flush this S*** out when I replace these gaskets and switch back to good old yellow coolant. Previous owner was a moron, don't know if he ever changed the coolant. Will I have problems switching to yellow, considering that I plan to flush it out thouroughly?

First and foremost, do a compression test on all cylinders.

The issue with the intake leaks is that they mist the cylinders with water as a slow leak. This washes down the cylinder walls and makes them wear abnormally egg shaped. At this point your engine may be destroyed and require replacement.

If your compression is good on all cylinders:

1. Order GM P/N 89017816 Lower Intake gaskets.
2. Order Dorman 615-180 Upper Intake Manifold.
3. New 195F Thermostat with 1mm hole in plate mod.
4. 2 Gal's Prestone All Make All Model Coolant. Flush every DROP of that dexcool out.
5. Might as well get the tune up parts at this time as well.
6. Check for excessive sludge in the engine lifter valley. If there is alot, flush with a good oil flush and change the oil.
7. Make sure all your parts are squeaky clean. If it ain't lookin new and shiny, you didn't clean it enough.
8. Follow the torque specs to the T and use loctite blue of some form for the bolts going into the aluminum, and on the lower intake bolts.
9. Your EGR Stovepipe is going to be the 5/8" tube - replace it with the 1/2" Dorman tube.
10. Replace your O2 sensor and belt while you've got everything torn down.

Well thanks for the pointers. I don't have the facilities/money/skill to do major tear downs. I'm well connected to a lot of automotive gurus though. Previous owner just didn't have the common sense to do this kind of routine maintenance, probably never took the engine cover off....

I planned to have the UIM, valve cover gaskets, LIM gasket, thermostat, EGR replaced by my guru mechanic and go from there. I figure he can also replace the sensors/hoses that are compromised as well. It just behaves like it has a vacuum leak and I'm betting that with the above maintenance it should improve.

I drove 1200 problem-free miles in this car after i changed the oil/plugs/wires/fuel filter myself, and that includes 4 2+ hour trips across Michigan for a total of at least 9 hours doing 75 on the freeway. Is it really conceivable that this engine is about to "destroy" itself? In less than 500 miles I plan to have the UIM replaced.