Valve seals????? need your opinion guys
#16
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Only 4 valves were reused. All others new. New guides seals, not sure on color ( don't remember) :-(
If the valve guides were replaced I seen the valve stem clearances as high as .007". That concerned me on my last engine refresh and I used SI valve guides. My clearances are .0015 and .002. All the valves were replaced.
http://sivalves.com/ocforeign_vguides_porsche.html
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As mentioned, most oil comes through the valves. Very little oil comes up through the rings in an upright or V type engine. During three of the four strokes the cylinder is under positive pressure, and gravity has the regular affect as well. Worn rings can pass some oil but not much, and it's typically burned off. Blue smoke is pretty much exhaust valve, guide, seal.
Leakdown is useful for damage, but not always for oil smoke. If there's intake valve issues, it can show up as plug discoloration.
Leakdown is useful for damage, but not always for oil smoke. If there's intake valve issues, it can show up as plug discoloration.
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In all likelihood it is valve seals, particularly intake, causing the smoke you are describing.
Poorly sealing rings should not cause oil to pool above the piston after the engine stops. In fact, poorly sealing rings may allow that oil to drain.
Worn valve guides themselves are not what “allows” the oil but could be the “cause” by preventing the seals from sealing properly. It is quite possible that replacing the seals will eliminate the smoke but if the guides are worn it could repeat.
Definitely perform leak down tests, etc. to identify any obvious problems before taking anything apart. The procedure Dave from Taz outlined should be quite worthwhile.
If those results are favorable, I would proceed with removing cams and checking valve stem wobble as docmirror suggests. The “wobble” test is by no means precise but about the best one can do without removing heads.
If none of this reveals anything alarming, I would install new seals and see what happens before pulling heads or engine.
Edit: Much truth in what JB posted. It is important to precisely observe symptoms and perform leak test as per Taz Dave.
Poorly sealing rings should not cause oil to pool above the piston after the engine stops. In fact, poorly sealing rings may allow that oil to drain.
Worn valve guides themselves are not what “allows” the oil but could be the “cause” by preventing the seals from sealing properly. It is quite possible that replacing the seals will eliminate the smoke but if the guides are worn it could repeat.
Definitely perform leak down tests, etc. to identify any obvious problems before taking anything apart. The procedure Dave from Taz outlined should be quite worthwhile.
If those results are favorable, I would proceed with removing cams and checking valve stem wobble as docmirror suggests. The “wobble” test is by no means precise but about the best one can do without removing heads.
If none of this reveals anything alarming, I would install new seals and see what happens before pulling heads or engine.
Edit: Much truth in what JB posted. It is important to precisely observe symptoms and perform leak test as per Taz Dave.
Bull**** !!! , guides leak only when there is lots of vacumn like deccel with throttle closed ....then as you get back on the throttle big puff of smoke.. Major oil issues tend to always be a ring problem as they leak oil ALL the time....the valve stem is a very small hole the pistons are huge by comparison !!
Last edited by depami; 01-09-2013 at 09:27 AM.
#24
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Maybe the springs on the seals popped off during instalation. If that much oil pools up when the engine is sitting, it can't be rings.
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maybe a few hundred miles. and dyno time.
today im going to track down a leak down tester and get to work checking that out. maybe my brain cant figure this out... but... even if the valve stem seal was not even there no way there is THAT much oil sitting above the valves right?
could be bad rings too, i did install them my self... :-P had a machine shop gap them etc (they had the block for measuring and what not)
today im going to track down a leak down tester and get to work checking that out. maybe my brain cant figure this out... but... even if the valve stem seal was not even there no way there is THAT much oil sitting above the valves right?
could be bad rings too, i did install them my self... :-P had a machine shop gap them etc (they had the block for measuring and what not)
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Mixed feelings about it...
I agree that the amount of oil is compatible with oil ring failure, but after few hours after parking, the oil should disappear, or reduce significantly.
I saw one intake valve failure in a Turbo Subaru engine (EJ25) with a similar amount of oil on cylinder number 1. But was a high pressure turbo engine (about 18 PSI of pressure) and no oil separator.
Once I'm learning about this car's engine, I would perform a leak test first.
I agree that the amount of oil is compatible with oil ring failure, but after few hours after parking, the oil should disappear, or reduce significantly.
I saw one intake valve failure in a Turbo Subaru engine (EJ25) with a similar amount of oil on cylinder number 1. But was a high pressure turbo engine (about 18 PSI of pressure) and no oil separator.
Once I'm learning about this car's engine, I would perform a leak test first.