Blow By

[V8KILLR]

Getting some big time blow by all of a sudden. I have been having some smoke and a little oil coming out of the valve cover breather.

Last night I seemed to be over boost at low boost, about 12 / 14 lbs. Not sure if it was over boosting. I have TurboLink, but did not hook it up because my laptop is not working.

This morning I popped the hood to take a look in the light. I was thinking that the fuel reg. hose vac. line just blow off and I was not getting the fuel I needed at high boost, but this was not the case, the line is fine. When looking at the engine, I noticed that there was a good amount of oil coming out of the breathers. Is it the PCV valve, or some thing else? The engine has somewhat low mileage, 48,000. However, I do beat on it pretty hard. Love to get in the high boost. I don't know if all these things point to the same problem or different problems. Any help would be greatly appreciated.

Thanks,
Jason

 

[xlr8ngn]

Do a compression test to see if it is a head gasket. You may also want to do a leak down test to check your rings. Look at your PCV valve. Boost or compression is getting in from somewhere.

 

[BJM]

Did your blow by change a lot recently or has it always been this way? My car is original at around 60000 miles and I think it has a fair bit of blow by. It may just be the way it is.

 

[V8KILLR]

I will likely do a compression test soon & leak down. I have a vacuum gauge in the car and I get about 11 lbs or 24 In. Hg. of vacuum. I think the compression is good. I would still like to know for sure.

Thanks,
Jason

 

[BJM]

My car drives fine and handles 16psi on 94 unleaded but blows more oil than I would like out of the vents

 

[John Purdom]

There was a recent thread on this subject entitled "here I go again, PCV valve". I'm sure there's more in the archives. True blowby is compression getting past the pistons/rings into the crankcase. In that case, you will often see puffing of oil smoke eminating from the breathers/PCV port even at idle. But our cars have other ways of pressurizing the crankcase. When you hook your PCV valve to a port on the intake, remember it now sees positive pressure as boost comes on. I pulled my PCV and could blow backwards thru it, so it was obviously allowing boost on my old motor to pressurize the crankcase. The the fact the PCV is so close to the valley pan, and picks up oil easily only makes the problem worse.

I am undecided as to how I will address this on the new motor. ATR offers a one way valve for the specific purpose of preventing boost from going back thru the PCV. I may do away w/the PCV valve altogether. If you look at many race cars, they will use a separator that runs a line directly into the exhust, using the scavaging effect of the exhaust to pull vapors from the crankcase. May experiment w/that method. Has anyone else tried this method of venting the crankcase?