95 Sentra main seal oil drip

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disinterestedbystander@mail.com - 14 Nov 2005 21:09 GMT

I'm thinking it isn't a problem with the seal proper, because it stops
dripping when the engine has been off for a while. This suggests that
there is pressure in the crankcase when it's running. Any agreement?

If so, what component(s) will prevent the pressure from venting? My old
Volvo had a plugged-up flame trap that caused the same symptom.

Any other ideas as to cause?

Thanks,

Tom

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Steve T - 15 Nov 2005 04:50 GMT

> I'm thinking it isn't a problem with the seal proper, because it stops
> dripping when the engine has been off for a while. This suggests that
> there is pressure in the crankcase when it's running. Any agreement?

No, it suggests there is oil pressure on the crankshaft bearings and when
the engine is off there is no oil at that seal for it to leak.

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Steve

http://www.atlantaracing.com

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disinterestedbystander@mail.com - 16 Nov 2005 02:02 GMT

I'm looking at a picture of the crankshaft in the shop manual, and it
looks as if there's about an inch between the end main journal and the
surface that the seal runs on. It doesn't look possible for oil
pressure from the pump to reach the seal.

If the PCV valve were plugged, would blowby gases pressurize the
crankcase?

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Steve T - 17 Nov 2005 07:31 GMT

> I'm looking at a picture of the crankshaft in the shop manual, and it
> looks as if there's about an inch between the end main journal and the
> surface that the seal runs on. It doesn't look possible for oil
> pressure from the pump to reach the seal.

The pressure isn't ON the seal but there is oil being splashed all around it
while the engine is running and is why they only leak while it's running.
It isn't sealing the oil that's in the pan from leaking out.

> If the PCV valve were plugged, would blowby gases pressurize the
> crankcase?

Sure you can try it but they don't normally plug up on these cars. I suppose
this IS the cheapest part that could cause this problem. Then again the
blowby would vent to the other end of the vent system and isn't going to
presurise the crankcase. Quick test is to remove the oil cap for a monet
while it's running, if the idle changes, the PCV is working.

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Steve

http://www.atlantaracing.com

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