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Oil on my spark plugs

DIKASUN

NAXJA Forum User
Location
Murfreesboro, TN
my 92 cherokee with a 4.0 has about 195,000 miles on it. i noticed about 6 months ago that my engine was kind of sputtering at certain speeds and i was getting terrible gas milage. so, the first thing i did was change the spark plugs. they were caked with white ashy chalky looking stuff. after i replaced them it runs fine for about a month, then i have to replace them again. is this a common thing or does anyone know what it could be?
 
If it's white i would look into a heat or lean issue. If its brownish(like burnt oil) or has oil on them, probable worn valve guides or seals.
 
White plugs means its getting too dang hot for em. Try replacing them and see how that goes for you as a first step.
 
What make and model plugs are you running ?
 
Bing bing's got the right idea, stick with that. In addition to the valve seals or guides, you should also follow Az jeff's idea and give it a compression check to see if the rings are wearing down. If you get any cylinders that are low, squirt a light oil into the cylinder and then crank it over and check the pressure again. If the pressure has come up, then you know the oil is helping to seal the gap between the rings and the cylinder wall, and theres your problem.
 
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