Crazy Amount Of Carbon Build Up On Piston

[Spyro]

I personally haven't seen this much carbon build up before, but I know it can't be normal. I took my engine out to fix some seals that were leaking, one including some seepage coming from the head gasket. As soon as I took the head off from the block I saw lots of carbon built deposits on top of one of the pistons. Looks like piston #4 if I'm not mistaken. Before I took the engine out of the car, I saw some soot spit out from the tail pipe on cold starts and black smoke when hitting Vtec at full throttle. The last time I did a compression test, I had 165 across all four. What could have caused this?

 

[Spyro]

I cleaned off the deposits....

 

[Esotericimage]

Typical high mileage engine..

but a little rich in #4 and just built up over time.

I would pull the pistons and check bearings, de glaze the walls with a flex hone, re-ring it and have the pistons soaking in Seafoam while all that is being done..
Then put it all back together.

 

[dmuney]

Valve stem seals and don't forget PCV valve yes tipycal high milage