GM 3.1/3.4 Intake Gaskets

I'm well aware of the troublesome reputation of the intake gaskets on these engines.
Would it be wise to replace the lower intake gaskets on a '99 3.1
as a preventative measure, or do some of these engines actually live to a ripe old age without spitting-out the gaskets?? No signs of coolant leaks yet (97k miles).
Regards, Al.
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170k on my 97 Lumina, never done, just watch for coolant loss very carefully.

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350k on my 90 Corscia nevr done. Still running fine.

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If you check your coolant regularly; maintain the proper coolant level and make sure that the radiator cap is the proper type and is functioning properly, you shouldn't have any problems. Many GM dealers are now advising customers to have a flush & fill done on DexCool systems at the 5 yr/50,000 mile mark.
The problem with those engines begins with impurities in the coolant that cause corrosion on the intake gaskets which in turn causes them to leak. Watch for "gunk" to form on the inside of the radiator cap and in the coolant recovery tank and if you see this, take it to a dealer ASAP to have the system flushed and clean DexCool re-installed.
Some people will tell you to flush the system and replace it with regular anti-freeze - DON'T. If you do this, you must be absolutely certain that you remove every trace of DexCool from the system or you will only create a problem where none may have existed before.
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Rich B wrote:

not quite enough. Ours had to be replaced well before 50k and I checked the coolant level at least every other weekend and topped off as needed. That is how I first noticed the leaking, I had to add coolant a couple times so I knew it was going somewhere.
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Not true in our case. Our 2002 Olds' intake manifold gasket failed at 44k miles, and I had been careful to keep it topped up with DexCool. GM replaced it under the MajorGuard extended warranty.
These failures are not all, or even mostly, neglect related.
John
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----------------------------- My 99 Century with 59,000 miles on it had the coolant level (cold) drop about 3/16" below cold line, but appeared to be clean. When I removed the cap, the level was down a couple of inches, and there was muddy goop around the neck of the filler. I suspected that a gasket leak might prevent the vacuum from pulling enough coolant back as the engine cooled. (I had never added any coolant). I had 75-month, 7-yr extended warranty, but always "never seemed to apply", so I was expecting to be disappointed again.....but when I mentioned that I was aware of the horror stories on the web, and reminded them that they might end up putting in a new engine, they agreed to do the job on the intake-manifold gasket etc, but they still managed to charge an additional $200. I thought everything should have come with the job, except that the warranty might have been $100 deductible. (This was at the Buick dealer).
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Spend $20 on an oil analysis at least once per year to catch the contamination before it becomes visible.
These guys are the ones I use:
http://www.blackstone-labs.com /
John
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