Leaking Boost into Crankcase

['94IDITurbo7.3]

i am leaking boost into my crankcase. had the intake mani checked and found .004" warpage at one end, gonna have that fixed but machinst doesn't think that is the entire issue and neither do i. i would think that gap would be taken up once the gasket is in there and the mani is torqued down.

Any other ways to get boost in the crankcase other than piston rings?

Thanks

 

[Black dawg]

the ring end gap is huge on these things....

 

[riotwarrior]

What shape are heads?

Guides could be an issue, and really there is no other way, the manifold should seal and keep boost out.

Simple if not manifold go down the passage to next part...valve/guide and then next in line...rings...could be rings and just not sealing, what was state of engine?

Do a comp test see whats the what.

You can do a comp test with manifold off if need be just make sure you DO NOT SUCK in anything!

JM2CW

 

[oregon96psd]

What makes you think your pressurizing the crankcase? Blowing the fill cap out or pushing past seals? Whats the story?

 

['94IDITurbo7.3]

i hooked a smoke machine up to a boost leak tester connected to the compressor housing on the turbo and was instantly getting smoke out the CDR tube and out the engine oil dip stick tube.

 

[Agnem]

i hooked a smoke machine up to a boost leak tester connected to the compressor housing on the turbo and was instantly getting smoke out the CDR tube and out the engine oil dip stick tube.

This is with the engine not running? I'm thinking you could pull your valve covers and do that test over and see your problem instantly. Otherwise, as others said... a compression test. But if the engine runs smooth this way, I doubt you have a cracked piston.

 

['94IDITurbo7.3]

Yes engine was off for smoke test. And the engine runs great otherwise.

 

[oregon96psd]

Is it possible that the smoke made its way through the same path as blow by does? Very possible your worrying about nothing, why did you even hook it up in the first place? Trying to diagnose something?

 

['94IDITurbo7.3]

I was low on boost and I was leaking around my compressor housing. I took that off and resealed it. Then rechecked it to make sure I had that fixed(which I did). Hook the air up to the boost leak tester, pump up to about 20psi, take air chuck off and it drops down to about 5-10psi of pressure within seconds. Didn't hear any external leaks so I hooked up smoke machine and got smoke out the cdr and oil dipstick tube. With the boost leak tester hooked up it should hold pressure for a little while. I know it will leak down a little just from valve overlap and the engine having blow-by at 243k miles.

 

['94IDITurbo7.3]

I think I will either buy or make a boost leak tester and check to see if this manifold work has done anything at all. If it still leaks like before I will take a video so you guys can see just how fast it leaks.

 

[riotwarrior]

DO COMPRESSION test first....then do your boost leak test.

If low comp, blow by is problemo!

 

[Ugly Moosling]

If you're pressurizing the compressor housing you may just be pushing air past the compressor side seal in the turbo, straight into the crankcase. Most turbos use a piston ring style seal, and rely on boost pressure balancing against the oil pressure to create the seal. Some turbos (I'm thinking early banks, but not positive) use a carbon seal which is a more positive seal. Try pressurizing at the intake hat and remove the compressor housing from the equation.

 

['94IDITurbo7.3]

That thought had crossed my mind.