first time posting.have a 95 bonny with about 115000 coolant in cylinders only,not in oil.is my problem uppr intake or lower?if i start by removing upper intak,how do i tell if its bad



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How were you able to tell you have coolant in the cylinders?

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Is your engine supercharged or non supercharged?

Pull the upper intake manifold. You'll find the EGR tube has burned through the plastic around it where there is a coolant passage around it. Dorman make a good replacement. If the engine was still running ok, you might be safe with replacing the upper intake. If it stalled abruptly and violently you might have a bent connecting rod or two. After you pull the intake and get the coolant out of the cylinders, run a compression check to verify. If you have some that are low, most likely you bent some rods.

took out spark plugs and coolant came out of several cylinders,this was after car refused to turn over after having ben turned off by my wfe in the driveway.I have since replaced lim gasket and upper plenum gasket,did not replace the plastic plenum.when i started it back up ,[I] have the same problem.so,is it the upper plenum itself?.I am confident the gasket job was done right as far as cleaning and gasket alignment,Is there anything else i should know about those type of gaskets.thanx for replying.Imso busy I have a hard time checking this forum.3800 vink 1995 115000

Pull the throttle body and look if you can see coolant in there. The EGR pipe can leak.

The good news is that it wasn't running when it filled the cylinders. The bad news, you need to pull the upper plenum off again. The EGR tube sticks up through the upper plenum. The EGR tube burns through the plastic upper plenum and allows coolant to leak into the intake manifold. Removed the upper plenum and inspect the hole where the EGR tube passes through it. Dorman products makes a good replacement upper plenum. Don't put a used one on and don't use the GM replacement part, it'* the same as the OEM part and will fail again.
More good news, you might be able to reuse any gaskets that don't come with the new plenum although I think everything you need comes with the plenum. This is the only failure I've seen that allows so much coolant in so many cylinders so fast.
Take Care. Dave

The upper plenum will be deteriorated where the EGR metal tube sticks up through the plastic surround to put EGR gases into the main air stream. Take a pick or small screwdriver and pick at the side of the plastic toward the coolant passages that go up into the plenum to the throttle body. You'll find the plastic is crystallized into little cubes. All gaskets came with the Dorman I got. Don't forget to replace the metal EGR tube that goes into the metal lower intake manifold with the new smaller diameter one.