Is this a symptom of bad valve seals? (pic)
#1
Senior Member
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Is this a symptom of bad valve seals? (pic)
Ive been having to change this plug in cylinder 5 every 300-400 miles because it will plug up with oil and stop sparking. I have a hard start condition sometimes, I see a little smoke at idle, and a little blue smoke at startup.
I made a mark on the top of the porcelain on the spark plug as it sat in the head, and when I pull the plug, the oil sludge is on the same side as the mark, meaning that the oil is coming from the head, not the rings. The other half of the plug (that faces the cylinder) is clean.
Cyl 5 is the worst (plug shown) cyl 1 and 3 have symptoms too, but not anywhere near as severe as 5.
This plug has 300 miles on it. Does the symptoms above indicate a bad valve seal?
305 TPI, 103k miles.
I made a mark on the top of the porcelain on the spark plug as it sat in the head, and when I pull the plug, the oil sludge is on the same side as the mark, meaning that the oil is coming from the head, not the rings. The other half of the plug (that faces the cylinder) is clean.
Cyl 5 is the worst (plug shown) cyl 1 and 3 have symptoms too, but not anywhere near as severe as 5.
This plug has 300 miles on it. Does the symptoms above indicate a bad valve seal?
305 TPI, 103k miles.
#2
Supreme Member
Re: Is this a symptom of bad valve seals? (pic)
could be sucking oil through the PVC -my crossfire was
doing that some though not as bad as what you show
-i don't know if there was someting wrong with the
baffle in my 'vette rocker covers(looked ok)but i put an
oil seperator in the PVC line to cure the problem.
I suppose bad valve stem seals could be causing the
problem too,but what you show would be a pretty bad
case-should be smoking a lot...
doing that some though not as bad as what you show
-i don't know if there was someting wrong with the
baffle in my 'vette rocker covers(looked ok)but i put an
oil seperator in the PVC line to cure the problem.
I suppose bad valve stem seals could be causing the
problem too,but what you show would be a pretty bad
case-should be smoking a lot...
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Re: Is this a symptom of bad valve seals? (pic)
My 454SS fouled up plugs on the passenger side about every 3000 miles. I changed the valve seals and the fouled plugs went away. The only way you'll know for sure is to change the seals.
There's also a possibility of bad rings, worn cylinders, worn valve guides etc. Changing the seals is a quicker and easier fix. A compression and leakdown test can pinpoint other issues.
There's also a possibility of bad rings, worn cylinders, worn valve guides etc. Changing the seals is a quicker and easier fix. A compression and leakdown test can pinpoint other issues.
#6
Re: Is this a symptom of bad valve seals? (pic)
I had the same on cyl 3. Did valve seals, even though they looked ok and valves felt like they were not "sloppy". Still had the same issue. Used a plug fouler and the car ran fine for about 1000 miles.
Pulled the plug out, still good! Compression on that cylinder now 35 pounds... putting a little camera into the cylinder showed a strange growth formation on my exhaust valve... not the typical oil sludge build up but really strange reddish "*****" growing all over the valve! Cross-hatching still clearly visible on cylinder walls.
Will be pulling engine soon to do a top to bottom rebuild...
Pulled the plug out, still good! Compression on that cylinder now 35 pounds... putting a little camera into the cylinder showed a strange growth formation on my exhaust valve... not the typical oil sludge build up but really strange reddish "*****" growing all over the valve! Cross-hatching still clearly visible on cylinder walls.
Will be pulling engine soon to do a top to bottom rebuild...
#7
Senior Member
Thread Starter
Re: Is this a symptom of bad valve seals? (pic)
I had the same on cyl 3. Did valve seals, even though they looked ok and valves felt like they were not "sloppy". Still had the same issue. Used a plug fouler and the car ran fine for about 1000 miles.
Pulled the plug out, still good! Compression on that cylinder now 35 pounds... putting a little camera into the cylinder showed a strange growth formation on my exhaust valve... not the typical oil sludge build up but really strange reddish "*****" growing all over the valve! Cross-hatching still clearly visible on cylinder walls.
Will be pulling engine soon to do a top to bottom rebuild...
Pulled the plug out, still good! Compression on that cylinder now 35 pounds... putting a little camera into the cylinder showed a strange growth formation on my exhaust valve... not the typical oil sludge build up but really strange reddish "*****" growing all over the valve! Cross-hatching still clearly visible on cylinder walls.
Will be pulling engine soon to do a top to bottom rebuild...
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#8
Re: Is this a symptom of bad valve seals? (pic)
#9
Supreme Member
Re: Is this a symptom of bad valve seals? (pic)
It's almost certainly valve seals PLUS something else. Like a badly worn guide (hold it slightly off it's seat and wiggle the stem around while you have the springs off to change the seals), or shot intake manifold gasket, etc.
Just bad seals shouldn't cause THAT much oil on the plugs in only a few hundred miles.
Just bad seals shouldn't cause THAT much oil on the plugs in only a few hundred miles.
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Re: Is this a symptom of bad valve seals? (pic)
To quote the chart in Haynes manuals "Oil is leaking past worn valve guides or piston rings into the combustion chamber ". Couldn't have said it better myself
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