For everyone who contributed to my last thread on my overheating Silhouette 3.4L, thanks; problem has been solved.
Turns out it was not head gaskets afterall. Go figure. But, as usual, you cannot determine whether it is gaskets or not for sure without committing to change the gaskets. So, I did that. Luckily, got a good deal on parts, found someone local to do it for about $800.00, so it turned into a $1,250.00 job, not the $3,000.00 that the dealer quoted. But the downside was that when everything was removed, he found that the intakes were completely clogged with "head gasket fix". I did not use any sealant, so the "clogged arteries", were caused by the GM dealer mechanic that I bought the van from originally. I guess that it was overheating on him, assumed that the head gasket was going again, and so did the "quick fix" and decided to dump the van, unfortunately on me. But, water under the bridge.

Now I have two new problems.
1) Since I got the van back, the exhaust sound has become "throaty". I also notice that when the van is stationary and idling, whether it the driveway or at a traffic light, exhaust vapours build-up in the cabin. When the van is moving, I get much fewer vapours or when I turn the fan onto "internal re-circulate" from external vent, the vapours disappear. I talked to mechanic and he says that he may have damaged some sort of pollution device at the back of the engine when he cracked the heads and it may be leaking exhaust vapours into the engine compartment, which are leaking into the cabin from under the hood. It sounds and acts like an exhaust gasket problem that I recently had on my Pontiac Vibe. Any thoughts out there.
2) Second problem is another area that the Silhouette seems to be famous for. I cannot seem to keep air pressure in one of my tires. Drops from 32 to 20 lbs. overnight. Have this problem with old tires, so I put a new set on. Problem occured on 3 of 4 wheels, even with new tires. Had new tires removed, rims re-cleaned, tires resealed and re-mounted, but the one wheel that was always the worst one, still looses air overnight. Mechanic says that it is the aluminum rims, because OE rims were nickel plated and the plating ozidizes (road salt) etc. and the bead loses it'* integrity. He says only solution is to replace rims. I don't want to through a set of crappy steel rims on, so has anyone an inexpensive fix for these nickel plated rims?

1. Buy some Sea Foam engine cleaner, with the engine running draw it into the intake using a vacuum line (like the one going to the brake booster) until the engine stalls. Let it sit for 15 minutes and restart the engine. You should get billows of white smoke coming out the exhaust and this smoke should make it easier to see where your exhaust system is leaking. You can get the smoke effect by sucking engine oil into the intake, but a nice side effect of using the Sea Foam is it will clean the top end of your engine. If you are not comfortable doing this, take you car into a muffler shop and have them find the leak. Don't drive the car until this is taken care of, and if you absolutely have to drive it, keep all the windows wide open (regardless of how cold it is).

2. Take the leaking wheel into a tire shop, have them grind the bead area down to clean metal, and have them coat the bead area with bead sealer. It'* black sticky $hit that is for this purpose. If that doesn't work, buy a new wheel.