Need Help-Excessive Blow By

Black Ice

Black Ice

c-pop
Joined
Jun 28, 2009
Messages
242
My 24v puller has lots of blow by on the street and track, compression test says rings and head gasket are ok, what are other possibilities of blow by sources
 
Im curious about this as well and only does it when drivepressure is really high. The only thing i can think of is maybe high crankcase pressures since my drive pressure so high. I need to remove the puke bottle because when it does this it hits the fan and cakes the underneath of the hood and leaves a film on everything. A friend told me to get a 12v breather for the tappet cover and also will run the 24v one and just lenghten the hose down by the axle.
 
cracks in the head? may only leak when the truck is running/hot. ??
 
kjpcummins said:
Im curious about this as well and only does it when drivepressure is really high. The only thing i can think of is maybe high crankcase pressures since my drive pressure so high. I need to remove the puke bottle because when it does this it hits the fan and cakes the underneath of the hood and leaves a film on everything. A friend told me to get a 12v breather for the tappet cover and also will run the 24v one and just lenghten the hose down by the axle.
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I got rid of mine on my 24V and ran a 5/8 hose all the way down with a #15 Adel clamp on the 10mm hex nut holding it down. I have some 5/8 unions and hose clamps holding the hose on. Makes a world of difference. The puke bottle made such a mess.
 
Probably high crankcase pressures as said before. Mine sprayed oil out of the vent tube when I was in it hard. Put a couple crank case vents in the valvecover and no more blow by
 
Yeah, engine runs fine, thinking of added 12v cover and vented catch can thanks for the help!
 
I have been told, with a severe vacuum leak the pump will blow into the crank case and pressurize it.
 
TURBOLVR said:
I have been told, with a severe vacuum leak the pump will blow into the crank case and pressurize it.
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I will find out for sure this week. Ive been having some extra smoke from the blow by tube lately and one of the last things I did before I remember it smoking this bad was remove all the vacuum lines.

Good thinking, thanks
 
blow by

yeah, i have lots of smoke as well out of the blow by hose. I added a 12v tappet cover with a hose along with the stock 24v location ran into a vented catch can. And still have lots of blow by. Did a compression test, every cylinder was over 420 psi. Ill check for vaccum leaks, but rtuck still goes in four wheel drive, so there should not be a leak
 
ive heard if oil splashing out the vent tube after running at high rpm, but usually no smoke issues.

could also be the turbo leaking boost into the return line?
 
brand new rebuild on turbo, thinking combination of boost pressure, rpms, and heat. Truck runs great ans makes good power.
 
if you are only checking the pressure at tdc then you could have an area in the cylinder wall that allows the pressure past the rings. you should try running a leak down test at about every 15 degrees on the compression stroke.
 
this is a very good idea, guess the compression check is only good for testing the rings and upper cylinder. thanks
 
yes the compression check will only test the rings at tdc. if you let the gauge sit for a period of time it would check to see if cracks in the head are allowing it to leak or a small hole in the head gasket. it would not test to see if the head is being lifted off the block. the normal wear on cylinder walls is in the center of the stroke.
 
im not seeing how thats possible. a compression test tests the entire stroke, a leak down only tests at TDC. if you try to do a leak down in a spot other than tdc the air will either rush out the open valve or send the piston to BDC... and fast.
 
I had a problem with this and at the same time my oil pressure was alittle higher than normal and then it went away when it went back to normal and hasnt done it in about a year.
 
best info ive got yet, thanks. Wonder if the truck being hot or cold would matter. thinking it would.
 
Rollin Coal said:
im not seeing how thats possible. a compression test tests the entire stroke, a leak down only tests at TDC. if you try to do a leak down in a spot other than tdc the air will either rush out the open valve or send the piston to BDC... and fast.
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if you test it at during the compression stroke the intake valve will be closed very close to bdc.
 
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