had to remove my intake manifold to get my one of my t-stat bolt holes drilled/tapped and i found this stuff underneath! is this 'sludge'? it was in two spots on the pass side of the motor (the spot in the picture, and another toward the back on the same side), but not on the other side.

i plan on just scraping it off and sucking it up with the shop vac. what problems might have this been causing?

 

"Sludge" is close enough. It's the product of petroleum-based oil & viscosity index improver additives broken down by heat. Scrapping and removing is a good idea - check the bottom of the intake manifold as well.

The main problem it causes is contamination of fresh oil when first changed. A little bit of it is desolved by the fresh oil, circulated through the engine - it doesn't make a very good lubricant.

Interesting location. It's usually under the exhaust cross-over passage.

 

That's what I was thinking too. I wonder if there could have been an intake gasket leak on that side.

 

i dont recall there being any fluids around the intake manifold on the pass side... would a manifold gasket leak possibly cause driveability issues similar to a vacuum leak?

here is a zoomed out pic of the pass side so you can see the 'sludge' near the back of that side. and FWIW, i'll also post a pic of the drivers side, which does not have any sludge.

 

when i had a manifold gasket leak i had a horrible drivability problem. no power and a horrible idle.

 

How many miles are on your car?

When I was changing my manifold gasket I found a nice half inch thick layer of crud all the way across the spider there....

It was what I would have considered sludge... about the consistency of cold jelly out of a jar.... It wasnt baked on or anything like that. Just my experience... I'm definitely no expert.

 

165k
not sure if the intake has ever been removed before by the previous owner.

 

Head gasket leaking? It could be some seepage from the cylinder oozing out. Looks like a lava flow, like something is slowly flowing out and building up. Otherwise the inside of that engine is clean.

RBob.

 

That definetly looks like head gasket! I would change them while you're in there, you'll be glad you did down the road. Sludge would be deposited more evenly throughout your lifter valley.