Ye Old Dreaded Upper Manifold Plenum (3800 Series II)

[bigsky]

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.

[maxwedge]

Originally Posted by bigsky

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.

[auto trainy]

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

[maxwedge]

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.