Ye Old Dreaded Upper Manifold Plenum (3800 Series II)

Just had the upper intake manifold plenum replaced on a 97 Park (was leaking coolant into the cylinders). Apparently this is a common problem, though an improved upper and lower manifold was used around mid 99-2000. I believe the LeSabre's didn't get a fix until 2003/05(?). Found a couple of good threads on this over at buickforums.com. Just a reminder if you have coolant disappearing with no external leaks, this could be the problem. At worst, the problem can hydrolock your engine.

Just had the upper intake manifold plenum replaced on a 97 Park (was leaking coolant into the cylinders). Apparently this is a common problem, though an improved upper and lower manifold was used around mid 99-2000. I believe the LeSabre's didn't get a fix until 2003/05(?). Found a couple of good threads on this over at buickforums.com. Just a reminder if you have coolant disappearing with no external leaks, this could be the problem. At worst, the problem can hydrolock your engine.
2005 had an alloy intake.

Hey max, I spoke to a friend(GM Service Mgr.) and he knows nothing of an alloy manifold,what's up.

I looked under the hood of a GP 2004 rental , I saw what looked like an aluminum manifold. Lucerne and Lacrosse also. Not PA, Sorry.