one fouled plug???
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one fouled plug???
my truck started to run like one cylinder was out. I suspected plugs, just because the tail pipe always looks so black, the first plug I took out, was quite fouled covered in gunk, and wet. but the rest of the plugs were a light tan color. any ideas what it could be, and how to pin point the problem. truck has about 110,000 miles on it,1994 (5.8), does use oil but you can't see it out the tail pipe. thanks Randy
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could a bad valve seal be leaking oil into that cylinder. the truck seems to use oil,doesn't leak, but yet you never see it burning blue from the tailpipe, the tail pipe is just suet black, could an ejector be bad and dumping too much fuel in that cylinder, I'm only guessing here. I'm putting in new plugs tomorrow, when I bought the truck about a 2yrs a go I put in plugs, new wires, rotor, and cap, and pcv valve
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I looked up what causes the condition of that carboned up plug and it said oil is getting into that cylinder some how, how can I determine if it is rings or valves?, If it is valves would new valve seals prevent oil from passing through the valve guides?
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From: The hills of No. Calif.
The old tried and true method is to pull the plug and do a compression test on that cylinder. Then add about a teaspoon of oil to the cylinder through the plug hole and test it again. If the compression goes up it's rings, if it stays the same it's valves. The oil creates a temporary seal around the rings that causes the compression to go up. Of course, it'll go up a bit anyway but a drastic jump would indicate rings.
You should also test the other cylinders for a comparison, I'd be interested in knowing if the compression is appreciably lower in that one cylinder than in the others. (Before adding oil.)
New valve stem seals can sometimes help, but they won't compensate for worn guides. You could pull a valve cover and look at the seals for that particular cylinder just to see if there's anything obvious like a seal that's come off the guide and is riding the stem or has deteriorated visably, something like that.
You should also test the other cylinders for a comparison, I'd be interested in knowing if the compression is appreciably lower in that one cylinder than in the others. (Before adding oil.)
New valve stem seals can sometimes help, but they won't compensate for worn guides. You could pull a valve cover and look at the seals for that particular cylinder just to see if there's anything obvious like a seal that's come off the guide and is riding the stem or has deteriorated visably, something like that.
