Wow, Archon, were you right on with your quote or what? !!

wf2tm51, on cars, the plenum usually refers to the piece with a throttle body(*) on one end, and an intake manifold on the other. The plenum on an L36 would be the plastic upper intake manifold. It is uncommon for the upper intake manifold (plenum) gasket to fail on the pcv end of this engine, and if it did, it would not leak coolant. The only coolant passages on the plenum are on the throttle body end. Those passages commonly fail. I am guessing that your dealer is referring to the lower intake manifold as a plenum.

If you described "lim" gaskets, or "L" -"I" -"M" gaskets to your Pontiac dealer, he might not have recognized the jargon that we use when writing, but if you said: "lower intake manifold gaskets" and he didn't know what you meant, you need to find another dealer.

I hope they install the new aluminum frame lower intake manifold gaskets for you. And, if your upper intake manifold is original or has a lot of miles on it, you should have it replaced at the same time. To find out how old your upper intake manifold is, take a look at this Techinfo article: http://www.bonnevilleclub.com/forum/...e=article&k=38

If the shop does not do the LIM gasket its just a band aid approach to the problem IMO.