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MNice

98 Bonneville, 3.8, coolant loss

6 posts in this topic

Just turned 250,000 and I noticed a major loss of coolant. My daughter uses this car to run back & forth to school, only about 4 miles each way, I used it whenever the gas gauge gets to 1/4, then continue on my 30 mile ride to work. confused

I always check fluids at least every 2 weeks, and this morning I added about 1/2 gal of coolant. No obvious signs. At first I was thinking heater core, only because the heater has been used more, but it didn't seem to have the coolant smell inside, and no humidity. I didn't have time at all to check things out well, so I'm just going to ask here what I can look for when I get home.

Thanks!!!

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If your oil level is overfull and no obvious signs of external leaks, then it sounds like the upper plenum

is leaking ans sucking coolant internal of the engine.

You would need to replace the plenum. Also I would check under the throttle body or by the drive belt and check for

puddles or coolant stains. It could be the lower intake gasket!

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There are so many possibilities that it would be worth your while to have it pressure tested. Since it started I would rule out the upper intake being cracked internally. If this did happen it would have more than likely hydro locked a couple of cylinders and broke the nose cone off the starter. The other possibilities are the radiator (tis the season), water pump, coolant nipple/elbow, crusty outlet pipes (leak where the hoses are attached), upper intake leaking externally near where the throttle body attaches to it, and loose hose clamp (again, tis the season).

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Well, my mechanic just called and after a pressure test it turned out to be the famous GM V-6 intake gasket. That's what I expected since the intake gaskets are still original, I did the plenum at about 130,000. Dang, only 250,000 and you have to fix something cry

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You just covered the two major issues with that motor. Should be good for another 250,000!!

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