Crankcase Ventilation

-
6

69Chrgr

Charger/Cuda
Joined
Jan 29, 2007
Messages
421
Reaction score
17
Location
Midlothian, Texas
Another question for the expersts here. After each run in my car, especially the 1/4 mile, it seems I'm experiencing EXTREME crankcase pressure blowing past the front main seal, and out the 4 breather caps on my valve covers. I have no PCV valve setup as of now, but I think I need to address this before I mess something up. Can I see some pic's of how some of you are addressing high crankcase pressure issues and maybe some suggestions to resolve this problem? It probably won't help performance wise, but I seem to have overlooked a major issue.

Thanks,
Darren
 
You have a ring problem! I have never used any crankcase evac on my drag car and have never had any problems. At WOT the most vacuum you will ever pull will be 1.5" with your four barrel so a pcv valve won't help much. An exhaust pan-evac will help a little more and a vacuum pump will do the most. I would check for a broken ring or an oblonged cylinder bore.
 
Bore taper will cause ring sealing problems right where it needs it most, at and near TDC.

Some racers use header style evac systems but they are unsuitable for the street.
 
Fishy beat me to it. The compression blows the air fuel mixture and the oil past the rings into the crankcase and out the breather tubes. Wow I just had a blonde moment. I drive a fish!
 
do a leakdown test to get the leak percentage
 
Your rings are not neccesarily broken. You have an excessive blow-by problem and we are trying to help. All of that blow-by should be pushing the piston down, not escaping past the rings or head gasket. I've seen head gaskets leak only under drag race conditions and/or N20 application, then be fine on the street for a while.

Like mrbill said, do a leak down test.

If you don't want to fix the cause, you have some options:

Live with dirty valve covers and blown front seals.
Use an exhaust evac system. A PCV system won't draw into the intake under wide open throttle conditions when you say this problem is happening.
 
I don't have head gasket problems, and I don't use N2O. I highly doubt I'm the only one with this problem, and to say that all of the rings are malfunctioning is still a little hard for me to believe. For ALL of the bores to be tapered is also a little bit too much for me to believe as well. Thanks for the help anyway, I think I can figure this out on my own. Thanks anyway.
 
Who saids ALL the rings are leaking? Just one cylinder can cause it. It HAS to be "blow by".

They do make wet sump vacuum pumps. Those can and do work good on street motors-but they are market as "race only" to keep the EPA happy :cheers:

I had a old motor years ago, it had broken rings, burning oil. Some spark plugs were always dirty, even when they had just a few hundred miles on them and the motor seem to be running smooth. I upgraded my ignition to a MSD 7al with a HVC coil. My spark plugs then stayed clean, even with the burning oil, and it smoked when first started after sitting for awhile. Just looking at the plugs might not tell you if its burning oil.

Do a leak down test, even a compression test. You may be surprise what you find.
 
I did a compression test and all cylinders were within 10 psi of each other. I should also add that I haven't driven the car much, just ran the crap out of it out at the track. Before I arbitrarily pull the engine and tear it down, I think that I should see if the rings will seat after a few hundred miles. However I will do a leakdown test as suggested before to see where I am at. This is a street car that I have only put about 3 1/4 mile passes on and 10 1/8th mile passes on. It probably has a total of about 10 miles of driving time on it.
 
The even compression is a good sign. You might want to try squirting a little oil down the cylinders and retesting the compression. That will seal up compression rings that aren't sealing good.

BTW: I don't know what kind of rings your running but I once used chrome rings on a Pontiac engine I rebuilt and it took them forever to seat in. Moly rings are much better about seating in faster so that's all I use now.
 
The motor needs to be broken in. Didn't know you had just 10 miles on it.

If you can, run a pcv valve while breaking it in. Take it out for a long drive.

What weight oil is it running. I use 20w-50 year round. Was told I am throwing away a little power over 10w-30 but I haven't have any engine problems either.
 
I'm using Valvoline 10w30 right now. I was also using closed valve cover breathers with small holes at the bottom. I just ordered open element K&N elements, hell I don't know, it may make things worse. I will still do a leak down test, however I am hoping to do a little driving soon and perhaps let it break in. I have Chrome Moly rings, gapped at .022 and .018 respectively. I also made sure the endgaps were staggered as suggested by the "How to Build a Small Block Mopar" book by Larry Shephard. I've also been told by many "Seasoned" drag racers that blow by was normal on high performance engines when you run the crap out of them at WOT. But, again, I'm just a novice. I just don't want to arbatrarily tear the engine down as it seems to run so strong.

Thanks,

Darren
 
The chrome molley rings can sometimes take a while to seat 500-1000 miles, depends on the courseness of the crosshatch among other things, take your time she should come around. 10W-30 should be fine.

Terry
 
Thanks Terry. I appreciate the feedback. Although something may definetely be wrong, I just couldn't see tearing back into a fresh engine that seems to run so well. I appreciate the positive feedback.
 
I didn't see where you said weather this is a rering on used bores or was the engine bored and oversize pistons used?
 
This is an overhaul, block bored and honed (with honing plates) .030, decked and line bored. Pistons .030, Protru forged from stroker kit ordered from IndyCylinderHead.
 
You must log in or register to reply here.
-

Back
Top