After much reading here on the forum about the "guaranteed" plenum leak, I was a little worried that my Ram might have a leaky plenum.

I was deeply concerned when I looked down the throttle body and saw all sorts of "oil" at the bottom of the intake. My buddy, who also has a 99 Ram that DID have a blown plenum gasket looked inside and said that it looked like mine might be blown.

I bought a Vacuum/Pressure Gauge for $12.99 at Harbor Freight and followed the instructions listed in the TSB.

The result? No VACUUM was present and the gauge showed about 2 psi of PRESSURE after 30 seconds of idle.

The bottom line? Do the test exactly as it is prescribed in the TSB before you jump the gun and spend a bunch of time under the hood doing something that is completely unnecessary.

 

That test will only work if the gasket is seriously blown. If you saw "all sorts of oil" , sorry, but it's blown.

 

I pulled my intake yesterday. (and broke off the front two intake bolts, such fun.) I had what amounted to a swimming pool in mine.....

 

As I mentioned in another thread, be sure to use a quality gasket and loc-tite the bolts before you torque them to spec and following the sequence. The bolts backing out is the biggest cause of this leak; I've actually found them laying in the valley.

That said, be glad that the magnum engine gasket failure only causes vacuum leaks and oil consumption. The vortec's often dump coolant into the oil and smoke the engines when their intake gaskets fail (and yes, when, not if)

 

If you are just replacing the gasket, cut the nipples off the end of the bolts. They are too long. And yes, use Loctite as suggested above.

 

I am pretty sure that the "oil" that was in the bottom of the intake is from the PCV valve. When I first got the truck and my buddy was telling me how to diagnose the plenum by looking down the TB, it looked like it was just caked on junk and not fresh engine oil. I sprayed it all down with carb cleaner and Seafoam Deep Creep and changed the PCV valve and the "oil" has not returned.

I really don't see how the engine would build pressure if the gasket was leaking to any degree.

I am going to continue to monitor the engine and every so often redo the test that is outlined in the TSB.

 

Good call. :-)

 

Except for the fact that the TSB won't show a small leak, and "your pretty sure the oil is coming from the PCV" your cat is slowly getting destroyed. I also say good call.

 

You're getting predictable.

 

What can I say? Other than it's a magnum!