I don't know if this has been addressed before, but after doing a little investigating with my new intake I have figured out why these engines cannot hold a plenum gasket.

The Problem:

The intake manifold is an all-aluminum part, but Dodge decided that it would be a good idea to use a steel plate for plenum cover. The heat expansion rates of steel and aluminum are different, so as your engine warms up and cools down, the manifold and plenum cover expand and contract at different rates. During the warm up and cool down time, the gasket is more susceptible to leaking due to this expansion difference, and is therefore prone to being "blown out."

The Solution:

Hughes Engines made a "permanent" fix to the problem by creating an identical cover out of 1/4" thick aluminum. Being made out of aluminum, the two peices now have the same heat expansion rate, and problem solved.

3.9L V6... http://www.hughesengines.com/Index/p...z&partid=22078

5.2L v8... http://www.hughesengines.com/Index/p...2&partid=22220

The only other way to "permanently" fix it is to cut your own plate out of 1/4" thick aluminum and replacing the gasket.

The Diagnosis:

When the plenum goes bad, it allows oil from the crankcase to get into the intake and will therefore add oil to the mix of air and gas going into the cylinders. This will not only burn oil, it will also cause the motor to knock. If you are experiencing excessive oil burning or an otherwise unexplained knocking, chances are very good that the gasket went bad and will need replacing. It's up to you to decide whether to just put a new gasket in or fix the problem for real.

 

Good write up! Will post up in tthe FAQ2.