1997 850 remove carbon buildup in intake manifold?

[bobthebuilder99]

I'm in the process of replacing the PCV air trap and related hoses and bits and parts, due to oil pooling on the valve cover, smoke out the dipstick and some oil leaks linked to plugged PCV components. The intake manifold has a significant carbon build up inside on all five inlets, right where it attaches to the head. There is some, but not as much buildup in the head. The intake valve stems and heads are clean. I've also got a bit of carbon on the spark plugs. Do I need to remove the carbon buildup in the manifold and head? It's on there pretty good and will take some scraping and chipping to remove. Always looking for a better way, I was reading about using SeaFoam via direct injection into the manifold through an unused vacuum line port on the tree. This process also causes voluminous clouds of smoke out the tailpipe. I don't know much about SeaFoam - is it a good product, does it really remove carbon buildup like I have? I wouldn't have a way of knowing for sure without removing the manifold, or at least the throttle body. The car was running just fine before I dissected it for the PCV job. Thanks for your comments.

[Ozark Lee]

Can you post up a picture? If it is really caked on then Seafoam probably won't do that much, at least in one shot. I give the cars a Seafoam treatment when I buy them and then try to remember to do it again every couple of years and it seems to help keep things clean.

I really don't have any direct before and after insight beyond what I did on my son's 850. On my son's car I did the Seafoam treatment (fuel, oil, and top end) and then did the PCV a few thousand miles later and it was fairly clean. What I don't know is what it looked like before but when we did the PCV I also dealt with the EGR hole and it was completely plugged. Since I didn't see it before the treatment I don't really have any perspective on what the "before" condition looked like.

The Seafoam smoke cloud clears up after a few miles on the highway and doesn't come back. You get some odd looks at first but my son actually videoed his car as it drove away and put it up on his Facebook page to amaze his friends.

...Lee

[bmdubya1198]

SeaFoam hasn't seemed to do very much for me. I've heard that the Gumout additive works better on automotive engines. I'm not sure what it's called, but it's in the same type of can as Seafoam.

[kahl]

I just my intake manifold back from a head repair shop and it is spotless. Well worth the $20.00.

[Bloitz]

I used oven cleaner (don't let it soak overnight because most "eat" aluminium ) + pressure washer and a toilet brush is what I used on mine.
It didn't get rid of everything but it was clean enough and cheap

I also tried burning it off with an air compressor and a large propane torch. Didn't really work IMHO. Great for drying though

If you have the option to have it cleaned like kahl, I would go that route.