The car in question is my friend's 2006 Buick Lucerne CX. Coolant leaks from the engine assembly somewhere and drips off of the bottom of the car on the left side, around where the engine meets the transmission, toward the back of the car. It is almost certainly not coming from the water pump or coolant elbows, I can see those clearly and it is dripping from the other side of the car entirely. I replaced the elbows with aluminum ones a year or two ago. I can see the heater hoses and their connection to the alternator bracket and the firewall are not leaking. I'm not sure exactly where it is coming out, have not been able to get underneath the car yet. There really isn't any coolant visible on what can be seen from the top.
Could this be from the manifold gaskets or something else like a core plug? (Are there core plugs in the end of the engine attached to the transmission?) There is no sign of coolant in the oil or going into the cylinders-- I thought most intake gasket leaks were internal-- and also this is a series 3 which was supposed to have relatively trouble-free gaskets. Relatively in GM terms though.
Coolant leaking from the back of a GM 3800 series 3
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The lower intake manifold has a bypass gasket just above the top bolts holding the engine and trans together. It is a rectangular protrusion 1 inch high by 3 inches long. Look by the exhaust crossover pipe.
https://www.rockauto.com/en/moreinfo.php?pk=2650156&cc=1382453&jsn=__GIP__30__
The bypass gasket almost never leaks; however, the lower intake manifold gaskets do. And for a 2006, it's about time.
I'm not going to go into deep denial that the intake gasket(s) may be bad, and I'm prepared to replace them-- my question was more whether it could possibly be something else back there. I don't want him to spend $75.00 on parts and not fix it.
If it were me, I'd pressurize the system while using a scope to see exactly where it is coming from.
When our coolant elbows would go on our Series III, it would always drip towards the back on the left of the engine. The aluminum elbows would never last more than two or so years for us. Switched back to AC Delco plastic after the second set of aluminum elbow failure and never had another issue.
Originally Posted by IveBeenRued
When our coolant elbows would go on our Series III, it would always drip towards the back on the left of the engine. The aluminum elbows would never last more than two or so years for us. Switched back to AC Delco plastic after the second set of aluminum elbow failure and never had another issue.
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Yep that's the fix. I make sure the bores where the o rings site is clean and smooth and put a thin film of Hylomar in there before assembly, they never leak.
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