oil mess coming from valve cover breather

[cool joe 03]

I have a 67 camaro with a 454. The engine is out of a 75 monte carlo. this had a stock rebuild about 5000 miles ago. I have a dual plane intake and a holley 750. the engine has aftermarket valve covers with breather. The problem i am having is the oil mess that comes from the breather. After cleaning the oil mess it only takes a few hundred miles and i have coating of oil on the rear half of the enging compartment. How do i stop this from happening?
thank you
joe

[dhardison]

Joe, do you have a PCV valve in one valve cover (connected to the large vacuum port at base of the carb) and a breather in the other valve cover?

Dan

[cool joe 03]

No, i dont have a pvc valve on the engine. Is this what i need to add to stop the oil from coming out the breather? Do you know haw to set this up?
thanks
joe

[dhardison]

Yeah, I only mentioned that because I had the same problem on my 454. In one valve cover leave the breather. In the other valve cover insert a standard PCV valve and run a hose from the PCV to the large vacuum port at the base of the carb (usually located at the rear). This will pull unburned fumes/gases from the engine/crankcase and recycle them through the carb. The breather will act as the 'intake' and is necessary so the carb doesn't pull a vacuum inside the engine/crankcase.

There's also a chance that your engine has excessive blow-by. This is when the rings are either worn or have not seated properly in the cylinders. This allows cylinder pressure to escape the bore during compression. Since that pressure has to go somewhere it takes the path of least resistance and exits your valve cover breather. If you remove the breather and/or dipstick, and can feel any postive pressure coming out, then it's probably blow-by. Let's hope this isn't the case.......

Dan

[cool joe 03]

Dan,
Thanks for the help. I dint think it is excessive blow by because i did a compression test not that long ago and it looked good. I will get a pcv valve and try that
thank you again.
joe

[69bigblock]

I have a similar problem, but not as much oil... I run 2 breathers only because I don't have a place to put the other end of the pcv...
Bryan

[Dan Pena]

Same here but on my small block, i have a breather and a pcv system to carb. i get oil seepage out of intake manifold and little out valve covers. I also think my breather sucks in moisture. well your advise is helpful. i gotta do a compression test.

[Norwoodx55]

If your valve covers don't have baffles under the PVC and or breathers, it makes the problem worse.
Brett

[Scott Parkhurst]

I like Moroso's breather kit to get them up and out of the way. It's not unusual for breathers to spit out a bit of oil. Baffles help plenty, and so does a PCV system, but nothing cures it like one of these setups: