Crankcase pressure

QMFB

QMFB

Fastest Welder in Texas
Joined
Apr 23, 2016
Messages
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Ok, I just built a 6.4L Cummins, and I am getting a LOT of blow-by. I built my own 1/2 gallon catch can (not returned piped yet) and I am getting a steady stream of (surprisingly cold) air coming from the can vent.
Can itself is catching almost a quart every 50 miles.
No "pulse" no "steam", no "choo, choo"....

Should I be looking at the turbos ?
 
If I power brake it, (stand on the brake and build boost) up to 20psi, oil ABSOLUTELY squirts out of the oil fill cap... WTF ?
 
We just finished a drag build with a 6.4 cummins. We have two -16 hoses off the valve cover going to a 5 gallon puke tank in the rear of the truck. We had a little bit of visible fumes from the puke tank while we were breaking it in on the dyno. Now after 10 dyno runs, 3 1/8 mile passes and 1 1/4 mile pass we have no more visible fumes and no oil has ever been pushed into the tank. I'd say you probably have an issue with the rings or something causing your blow by. Did you assemble the engine or was it assembled for you?
 
What rings are you using? And how many miles? Recently had a similar issue, and it was partially because it took a little longer for the rings to seat. I was using total seal second rings.
 
10-4. Thanks fellas.
Yeah, it's under 800 miles on this build, and I haven't been able to beat on it yet because if transmission issues (ATS, always issues).... But it's concerning because it seems to be getting worse, not better.
 
Yotadzl said:
What rings are you using? And how many miles? Recently had a similar issue, and it was partially because it took a little longer for the rings to seat. I was using total seal second rings.
Click to expand...

I'm using Cummins rings and pistons.... No mahle, no McBee....
 
Definitely needs the rings seated. Did my 5 min cam break in then beat the piss out of it.
 
Like the last guys said, you gotta run it. Don’t baby it, get those rings to seat. If you have a trailer to put some weight on and tow around, even better. Find some hills to pull.


Sent from my iPhone using Tapatalk
 
after i built my first one, after the cam break in period, both les and Hamilton told me to hook up to my toy hauler and get it hot, let it idle (heat soak) then repeat.

best of luck, hope its not ring gap!
 
Start simple.
What are you using for a baffle between the oil and the crankcase vent?

Sent from my XT1575 using Tapatalk
 
The baffle that comes with the G&R Diesel valve cover
 

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QMFB said:
Ok, I just built a 6.4L Cummins, and I am getting a LOT of blow-by. I built my own 1/2 gallon catch can (not returned piped yet) and I am getting a steady stream of (surprisingly cold) air coming from the can vent.
Can itself is catching almost a quart every 50 miles.
No "pulse" no "steam", no "choo, choo"....

Should I be looking at the turbos ?
Click to expand...
What was your piston ring side clearance?
 
Loose of OE spec... But definitely not "holy piston slap, Batman!" Territory.
 
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