<VV> RE: Rings, vacuum, carbon seals, etc.

[Duane, Jim (US SSA)]

Hi Steve, good point.  I have run RT.2 from eastern MA to NY on my way
to Troy NY and there are some real steep hills.  No smoke!  If the turbo
seals are good and there is no blow-by, then either the oil is being
drawn by the rings during a slow intake stroke, the guides are getting
splash from the pushrods or turbo return line, or the turbo seals
somehow fail at idle.  Add to this mystery the fact that Craig has
rebuilt his turbo and has oil in the intake, and it's time to call CSI!
I will be checking my own as soon as we thaw out here in the northeast.

	JED

-----Original Message-----
From: virtualvairs-bounces at corvair.org
[mailto:virtualvairs-bounces at corvair.org] On Behalf Of Steven R. Marti
Sent: Tuesday, March 06, 2007 5:08 PM
To: virtualvairs at corvair.org
Subject: <VV> RE: Rings, vacuum, carbon seals, etc.



FWIW, I did notice an appreciable difference in vacuum, but the stock
rings in my engine were gonzo!  I noticed the smoke stopped bellowing
out the oil cap, though!
	I also played with the crankcase vacuum line, removing it (and
the restrictor) to determine if the reduction of vacuum had an effect. I
need to get a plug for the oil line before I try my "oil-less" hot idle
test.  Could the pulses in the intake cause the turbo inlet seal to see
varying vacuum and that in effect causes the oil leak?  Is this
complaint just from turbo owners? Is Crawford offering Craig and me his
turbo to run the hot idle test?
	Come to think of it, we have a member in our local with a spare
turbo...AHA!  A lot safer to try another turbo than to run mine dry!
;>)

JED

A SMOKIN' '66 180 Corsa CVT
Colonial Corvairs
CORSA
    
> Crawford said:
>
> "I recommend that the fellow with the leaking turbo carbon seal 
> replace the
> seal where he has seen that he has oil in his intake. It doesn't make 
> sense
> that the increased engine vacuum is causing the problem and I would
> certainly not change the engine's piston rings because the turbo is 
> leaking
> oil!  Also, you may be permitting gasoline to wash into your turbo 
> bearing
> by continuing to run the turbo with a bad carbon seal."
> -----------------------------------------------------
>  I have rebuilt my turbo with new seals and according to the shop  
> manual. I suppose I could have screwed that up but everything was set

> up to specs in the manual. I have read of increased vacuum causing  
> this problem in Hugh McInness" book about turbochargers, so it does  
> make sense to me. Remember, the problem shows up at extended idle  
> periods where the vacuum is highest.
>  I also don't think much gasoline could get past the seal since it is

> on the intake vacuum side of the seal.
>
> Craig
>
>


Isn't the highest vacuum condition going to be coasting against the
engine
with the throttle closed?   Seems like that's going to be higher than
any
idle vacuum, regardless of piston ring design.

If the turbo carbon seal works (doesn't smoke) coasting against the
engine
with the throttle closed, I'd guess it's not the turbo.

Steve
 

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