Hi I have a 92 GMC Sierra 4.3 V6 about 127K miles. I bought it a little
over two years ago from the original owner with about 92K. The truck was
pampered and came with a thick stack of receipts for repairs and maint
done over the years. I have had absolutely ZERO problems of any kind
--until now. The cooling system went from nice green coolant to rust
almost overnight. This morning I topped it off and let it run for a few
minutes. Looked in the overflow tank and saw bubbles. I know that
usually means head gasket, but can intake manifold gaskets also cause
that? I know some GM engines had bad problems with them. Is this engine
one of them? It also recently started getting a "check engine" light
intermittantly, and the almost unbelievably great gas mileage-- about
20-- dropped to about 16. There does not seem to be any water in the
oil. I am not driving the truck anymore until I can get it to a friend's
shop, and get it fixed, but I'm just curious, and a little worried. I
love the truck and am going to keep it regardless of what it takes to
fix it-- just wanted some idea what to budget for. As to a previous
thread about 20 year old vehicles-- here's a 19 y/o, and this weekend
I'm going on a 500 mile round trip in my 86 C10 6.2 Diesel-- since the
problem with the other truck. (high school reunion -- shudder -- 40
yrs) . FWIW, I don't see that many new style Tundra's
here, and "here" is San Antonio, where they are made. Don't know anybody
who has one, other than a friend who had a rental while the ins. co. was
settling on his totaled 03? F150. He said he didn't care for it that
much and would never buy one.
Any and all info/advice on the 92 V6 will be greatly appreciated. Thanks
Larry

Lp1331 1p1331 wrote:
I would bet you need intake gaskets and probably new O2 sensors as well.

The bubbles were more than likely air being purged out of the engine as
it warmed up, after you topped off the coolant. The color change could
be air or more likely the coolant got low and air in the system formed
some flash rust that colored it.

The bad intake gasket is letting coolant get into the intake runner,
this gets run through and causes the O2 sensors to be contaminated. You
get crappy mileage and a check engine light as well.

Make sure you use the good steel cored gaskets and follow the new torque
specs when you install them.


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Steve W.

On Wed, 28 Oct 2009 22:47:47 -0500, Lp1331 1p1331 fired up the
etcha-a-sketch and scratched out:

What steve said.

You have a 17 year old truck with 127K miles. You need new gaskets.




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--
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