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Rear Main leak above 3000 rpm only?

72golddustermike

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I have tried three different seals and a hughes seal and seal retainer. Last attempt I clocked seal at 6 and 12. It does not leak at idle for 25 mins. Next went to 1500 for 5 mins,2000 for 5 mins, and 2500 for 5mins no leaks. I ran to 3000 it starts leaking. I have put dye in so I for sure see the glow coming frim rear main. I am down to trying the rope seal. Fresh engine under 150 miles stock valve covers pcv valve sticks to finger when pulled and stock breather on other side.Any help would be greatly appreciated.
 
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Sounds like it's building pressure and the crank case is not ventilated properly...
 
BpBp makes a great point, you see a lot of engines not vented properly. Also, is the seal area of your crankshaft smooth or knurled? (crosshatch pattern)
 
Have pvc on pass side if i take out and stick finger to it it suck my finger to it. Driver side has breather stock valve cover. Original crank knurling worn down where rope seal was. Fresh build less than 150 miles
 
You can get better PCV valves that compensate for RPM. Or you might have excessive blow by.
 
Out of balance amplified by rpm? Not sure in this but it makes a bit of sense?

A pump at 2500 would make the same pressure at 3000? Just thinking outside the box and am probably wrong
 
Maybe go back to a rope seal if you have a rubber seal? Old timer said the rope seals were better.
 
Just dealt with this on a freash 440. Put 3 seals in a rotisserie restored car. Ruined a new centerforce clutch. All 3 seals were rope type installed by engine builder. Ended up with no pvc and 2 breather vents. Its cheap to try.
 
i don't know how many seals I've done thru the years. all neoprene and no leakers (did I jinx myself?). I don't use a lot of oil pressure, don't like loose mains, and am careful about over filling the sump. I would look at as many other issues, beside the seal, as possible. you could be changing seals forever and never fix the problem because of something else.
 
as others have said a windage is a must . i have that oil pan on my stroker it painted black look at my pic and you can see it. your stroker is bigger than mine so think of the turbulence in the pan it will whipped the oil in to a foam and through up on the cylinder walls and burned. is the dip stick in right ? i.e all the way down and seated to block?
 
as others have said a windage is a must . i have that oil pan on my stroker it painted black look at my pic and you can see it. your stroker is bigger than mine so think of the turbulence in the pan it will whipped the oil in to a foam and through up on the cylinder walls and burned. is the dip stick in right ? i.e all the way down and seated to block?
Yes
 
To me, if it was only a sealing issue shouldn't it leak whenever there's oil on it? Once there's a breach, rpm shouldn't matter, that oil's sneaky stuff it'll find it's way out...like @vance.dykes stated above a leak down test is probably in order, check the seal on those rings. To rule it out.
 
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