Questionon my inline 6 258 4.2 liter, the plastic valve cover leaked so i got an alluminum one. I noticed yellow stuff in my air cleaner and the tubes that come out of the valve cover. goodyear told me it could be the valve cover, they say they see this probplem with newer jeeps with metal covers.well i talked to a jeep teck at 4wd.com and he said he never heard of it, and u told me u didnt think it would be the cover, goodyear a while back checked my jeep and said the headgasket is fine. so i took my valve cover of clean all the yellow stuff out of it and the tubes and cleaned the push rod replaced the oil with synthetic oil and bought a new pcv valve. i put it all together and let the jeep run for maybe 15 minutes in idle. when i checked the tube coming out of valve cover it had a little bit of yellow stuff in it, and when i took oil cap off and ran my finger along the inside of top of valve cover there was a fine layer of whitish yellow stuff i could scrape off, this makes me think that it is the valve cover, the yellow stuff is not on my dipstick.good year told me that when the engine cools, condensation gather on the metal valve cover inside and mixes with oil. Now i stumped, and in a bad spot, i cant return the cover which i payed 120 for, and i would have to buy another plastic cover which will probably leak. what would u do in this situation, good year said its bad for the jeep and i would prabably hav eto periodically take the valve cover of and clean, which would suck.
AnswerAMC/Jeep used metal valve covers for many years prior to installing the plastic one.
Condensation forms in all engines, that's why it's important to have the proper thermostat and to get the engine to it's operating temperature. The heat of the engine causes the condensation to evaporate. A properly operating PCV system will then take the vapors an introduce them into the air/fuel mixture going into the combustion chambers.
The following are just a few of the things that can cause excessive sludging in your engine:
1) Restricted PCV valve or hose. Remove the PCV valve from the valve cover while the engine is at idle. Place your finger over the valve to check for strong vacuum.
2) Excessive blow by. Perform a cylinder leakage test. Each cylinder should be less than 10% leakage.
3) Cracked cylinder head. Make sure the engine is at operating temperature when performing the cylinder leakage test. A radiator pressure test is also helpful.
4) Engine not reaching operating temperature. Make sure you have the proper thermostat in the engine.
If the condensation (yellow stuff)is mixing with your oil, why isn't the oil in the crankcase yellow?
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