with oil fouling the plug...
I need help
Thread Starter
Pro
Joined: Oct 2004
Posts: 644
Likes: 15
From: Clarksville Tennessee
I need help
I have a problem with the #4 cyclinder. The spark plug was fouling from what I'm guessing is oil. So I changed the Valve stem seal. Drove the car for a couple of miles and recheck the new plug and it seem to be fine. I drove the car everyday for a week and it started doing it again. I did a compression check on all cyclinders and they were all the same(180 psi). I'm not sure what to do at this point. Is there's something else I over looked that could cause this? I posted a link/ picture of the plug. This engine has about 7k on it.
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
that is definately oil fouling...
a compression test is rather useless, you need to run a leak down test. a leak down will check the cylinders capacity to maintain pressure.
I don't know why you would want/need to replace a valve seal on a new motor like that. If it's that new, you might have a warrantee claim, if it is a head related problem. There is a chance that the head shop didn't properly hone the new valve stem seals.
a compression test is rather useless, you need to run a leak down test. a leak down will check the cylinders capacity to maintain pressure.
I don't know why you would want/need to replace a valve seal on a new motor like that. If it's that new, you might have a warrantee claim, if it is a head related problem. There is a chance that the head shop didn't properly hone the new valve stem seals.
Thread Starter
Pro
Joined: Oct 2004
Posts: 644
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From: Clarksville Tennessee
Thanks Bogus
... I replaced the intake Valve stem seals hoping that was the cause of the problem. Valve stem seals is the least expensive and less time consuming when trying to solve an fouling spark plug problem. I need to find a cyclinder leak down tool and hope for the best, but expect the worst.
... I replaced the intake Valve stem seals hoping that was the cause of the problem. Valve stem seals is the least expensive and less time consuming when trying to solve an fouling spark plug problem. I need to find a cyclinder leak down tool and hope for the best, but expect the worst.
Thread Starter
Pro
Joined: Oct 2004
Posts: 644
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From: Clarksville Tennessee
Burning Brakes
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Melting Slicks
Joined: Apr 2002
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From: St. Charles, MO Route 66 Corvette Club
Rssshen: When you replaced the valve seal on #4 cylinder, did you feel for any radial movement of the valve in the head? From what you said in the initial posting, the replacement of the valve seal seemed to help for a few days and then went south. You may have what Bogus suggested: "There is a chance that the head shop didn't properly hone the new valve stem seals". This would quickly wear out the new seal and then leak oil into the cylinder. This condition would not impact the compression on that cylinder.
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Thread Starter
Pro
Joined: Oct 2004
Posts: 644
Likes: 15
From: Clarksville Tennessee
.... I'm thinking this has to be a simple fix.... I hope... If not.... it will open the door for me to ask Santa for a 396....
Thread Starter
Pro
Joined: Oct 2004
Posts: 644
Likes: 15
From: Clarksville Tennessee
Rssshen: When you replaced the valve seal on #4 cylinder, did you feel for any radial movement of the valve in the head? From what you said in the initial posting, the replacement of the valve seal seemed to help for a few days and then went south. You may have what Bogus suggested: "There is a chance that the head shop didn't properly hone the new valve stem seals". This would quickly wear out the new seal and then leak oil into the cylinder. This condition would not impact the compression on that cylinder.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
There is a chance that the head shop didn't properly hone the new valve stem seals.
You walked right into that one, buddy
Team Owner
Joined: Aug 2000
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From: San Pedro CA
Safety Car
Joined: May 2006
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From: Salem NH
When I changed the intake seal I didn't feel any unusual raduis movement. One thing I didn't do... that may make a difference is change the exhaust seal. I'll change it this week. As for the head work.. I brought them brand new from DART fully asembled, so I hope it's no major or minor defect in the head.
What type of valve seals did you use? Hopefully not unbrella type. I really like the OEM seals for 4.3l truck motors, they seal great, but don't chew up the valve like some of the teflon seals.
A leakdown test will show you cyl leak issues, but won't show you a bad oil control ring. Oddly enough, a cyl with an oil issue often shows an abornmally high compression test reading. (you stated they all came in at 180).. Weird stuff. Wish you were local, i'd love to tinker with it.
You have a PCV right?
-- Joe
Le Mans Master
Joined: Oct 2003
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From: seattle WA
honing valve seals...that was a new one on me I think I'd opt to first try the fuel pressure test just to eliminate that from the equation, plug looked fouled to me but I really couldn't tell by the pic if it was oil or gas. And you may want to ohm the plug wire. I was brought up with compression testing and I still have alot of confidence in it...but it won't show a bad valve guide, and that could be the problem.
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
honing valve seals...that was a new one on me I think I'd opt to first try the fuel pressure test just to eliminate that from the equation, plug looked fouled to me but I really couldn't tell by the pic if it was oil or gas. And you may want to ohm the plug wire. I was brought up with compression testing and I still have alot of confidence in it...but it won't show a bad valve guide, and that could be the problem.