I just removed my buddys head from his 99 si with the Greddy turbo kit. The valves are so covered in carbon that they were not sealing. The buildup is around the base of the valve right where it begins to flare. Our mechanic had never seen this before on such a highway driven engine.
My question is how would so much carbon build up on the valves? It's daily driven car with 75k. It has been turboed for about 23k of the 75. Could running stupid rich cause this situation? Pics of the valves will come later tonight. the exhaust valves were worse than the intake.

 

Carbon can be caused by running rich, but what did the plugs look like?

 

plugs looking ok

 

Running rich would definately do it.

What did the tops of the pistons look like?

Common problem: If the valve seals leak any oil, then that oil will bake onto things like the valves and piston tops.

 

I was just going to mention the valve seals and someone beat me to it...
I'd check them, and your rings. You could be burning oil. You plugs would look dark and very tarry if your running rich. It could also be the normal build up inside the engine. I forgot to ask what is he using for fuel management?

For future reference:
You can always take a spray bottle of alcohol to the TB while the engine is idling and just squirt away to clean it while running.


[Modified by tzsir, 12:14 AM 1/3/2003]

 

The top of the pistons were also covered in carbon. Not too much but there were some thick spots. They hot tanked the head and it looks great now. Nice and shiny combustion chambers. I was going to take a pic of the valves but they already cleaned them up.
I forgot to mention that the turbo seal blew allowing oil to seep into the compressor side. Oil was coming out of the bov. We removed the charge pipe and whew! there was so much oily vapors coming out I'm surprised the engine would even idle. He was driving it like that for about 6 months not knowing. For those 6 months a oily vapor was ingested into the engine. I think this is where the excessive carbon build up came from. He's also running rich too so that did not help either. Hopefully his cat is not damaged from all the oil vapors.
So basically they just removed the head, cleaned the carbon and re-installed everything. See tomorrow how it turned out. First up is a compression check to double check that it has improved.