So I'm changing my plenum, water pump, and timing chain today and noticed something... odd... about my intake gaskets. The areas in the yellow circles were well attached to the head and intake, but the area in the middle in red was not. In fact, it seemed to not be attached (stuck) at all.

For you other guys who have changed your plenums, is this normal? It seems like those would be areas where there wasn't a strong seal, potentially messing up my air/fuel ratio.

Thoughts?

 

Isn't the A/F ratio monitored at the front O2?... therefore any additional air via an intake leak would be accounted for when the O2 saw a lean condition.

A failing gasket at that point (between ports) would be an oil leak issue, not air.

 

Pretty common from what I've seen. Just be sure to clean all remnants of the old gasket and follow the notes in the plenum replacement thread.

 

Yeah, gaskets to odd and strange things. They will stick like they were welded in some spots, and peel off easily in others. Nothing unusual.

 

Thanks. I feel better. I've never torn this far into an engine before and expected nice, uniform wear like you would see on smaller gaskets like water pumps, oil pans, etc...

 

BTW, don't forget to change out your distributor cap, rotor and plug wires while you have the intake off - it makes changing those parts so much easier..

 

Use a wet/dry vac to clean out the intake valley, intake ports, all of it. This is where I say change the lifters while you are in there, no time better than now.