Lots of carbon buildup on valve stems. Help.
12-06-2001, 09:09 AM
#1
Le Mans Master
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Location: Watkinsville, GA and Glen Cove, NY
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Lots of carbon buildup on valve stems. Help.
Pulled of my intake manifold as I am going with a high rise and shined a flashlight down the intake ports and there seems to be quite a buildup of black crusty deposits in the back and stem of the valves. This motor supposedly only has about 6000 miles on it. It does use some oil also. I know this is a tough question to answer but how much of this buildup is normal. I have read that the stock umbrella type valve seals on big blocks typically don't last long. Should I pull the heads or not. Also when I pulled the old intake of some dirt fell down into a couple intake ports. I can get some of it out, should I worry about all of it or not. Thanks.
12-06-2001, 10:04 AM
#2
Le Mans Master
Re: Lots of carbon buildup on valve stems. Help. (69ttop502)
A light coat of deposits is normal, a thick deposit is due to bad valve stem seals and/or worn valve stems/guides.
The dirt that fell down the into the port can get caught between the exhaust valve & seat on the way out (causes burned valve), or between the piston & cylinder wall (causes scored wall). Try a large (2+ inches) garage vac with a small (1+ inches) nozzle. If you can't get it to come out (start with a clean vac to see), use compressed air to urge it out.
Don't spray any fluids in there... if the valve is open, the fluid will wash the dirt into the combustion chamber.
The dirt that fell down the into the port can get caught between the exhaust valve & seat on the way out (causes burned valve), or between the piston & cylinder wall (causes scored wall). Try a large (2+ inches) garage vac with a small (1+ inches) nozzle. If you can't get it to come out (start with a clean vac to see), use compressed air to urge it out.
Don't spray any fluids in there... if the valve is open, the fluid will wash the dirt into the combustion chamber.
12-06-2001, 10:10 AM
#3
Burning Brakes
Re: Lots of carbon buildup on valve stems. Help. (69ttop502)
I'D worry about it! If you have ever heard a piece of carbon break off and fall into the cylinder and listen to it bang around. It usually smashes into the plug. and distroys that so you can easily identify what cyl. is miss firing, but that is wear the benifits stop. Depending on how big the piece is it could stop a valve from closing (sticks in seat) then the piston comes up and closes the valve for you pretty soon you have a mess. Sorry for being the bearer of bad news but make sure you know what size fell in the cylinder.
Hey tom454 we were typing at the same timeafter I posted I saw yours. Nice to see we are on the same Page:)
[Modified by paso, 8:13 AM 12/6/2001]
Hey tom454 we were typing at the same timeafter I posted I saw yours. Nice to see we are on the same Page:)
[Modified by paso, 8:13 AM 12/6/2001]
12-06-2001, 12:42 PM
#4
Safety Car
Re: Lots of carbon buildup on valve stems. Help. (69ttop502)
Engines used in cars primarily driven on the street all exibit this buildup. Most street engines suffer from short or incomplete warm-ups, low performance demands, and lower quality fuel. Also, even slightly loose seals (no oil consumption) can contribute to this. Every street engine I tear down has this problem, some are just worse than others.
Hans
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