Lower Intake Gasket Failure.
 

This is a lower intake gasket off a 1999 L67 Buick Riviera. Accoding to the date stamp on the gasket(1998) this has been installed for about 3.5 years. Unknow length of time the car sat non-running prior it getting to the junkyard.

I scanned this EXTRA big so we can see the details. I wish I could find a used aluminum gasket, but we are just going to have to use the lack of complaints as data. After previewing this post, I just seen HOW big it is. It would probably be best to right click on it, and save to your desktop so you can use Windows to zoom in and out with.


PORTS 1, 4 and 6 are the intake ports. #1 seems to be fine. At the bottom of port #4, you will see that the gasket is just starting to push out from the plastic frame. And, #6, the frame on the right hand side has completley failed. You can't really see it in the photo, but you can see right through between the gasket and the larger part of the frame. At the gasket nipple.

PORTS 3 and 5 are the coolant ports. Common failure area right here. If you look close, you can see where the MFR made weak points in all 4 areas of that smaller frame. This allows the frame to expand and contract leading eventually to failure.

PORT #5, I barely see it in my hand, but there is another hole between the rubber seal and the main frame. This would eventually allow coolant to weep along the seals and flow into an intake port due to the natural vacuum.

Like I already said, if I had a used aluminum framed gasket, it would make a great comparison for this post.

What can you do to prevent failure? It's not a question of "if", but WHEN will it happen. The longer these gaskets are installed, the higher percentage of failure.

Common symptoms of failures include:
1. Leaking out the side of the manifold.
2. Engine sucking coolant in and burning it out the exhaust(misty and sweet smelling exhaust).
3. Coolant in the oil because it naturally flows downward with gravity, and then it gets into the lifter valley and into the oil pan. This is a long term destruction if not noticed early on.
4. Hydrolock. This is the worst one, and can destroy an engine in a second if running at high RPM's.



http://www.kc2jga.com/l67gasket.jpg