I have a 352 engine in a 1945 ford pickup and have had a little problem with oil coming out of one breather cap. The valve covers are cast aluminum and I am running a edlebrock streetmaster intake. My engine vacuum is running about 19. I have good vacuum in pcv valve running on connection in the base of carter afb carb. Why is it that there doesn't seem to be any vacuum in the opposite valve cover ? I adapted a gauge into the breather opening and get no reading at all, but yet get a reading of 19 on the cover with the pcv valve.

 

I wouldn't think you would get the full vacuum out of the valve cover. The PCV is supposed to control how much vacuum is in the valve cover. Since you are not sucking oil through the PCV, hold that thought.

Your breather should be taking air in. (most pull clean air out of the air cleaner, but there are other ways to get clean air.) Since oil is coming out, I think you have an oil drainback problem.

How long since you've had the valve covers off? How long since valve seals were installed?

Ford's neoprene "umbrella" valve seals fall apart and clog the oil returns.

This has come up recently in another post.

 

Had valve covers off last week to replace leaking rear manifold gasket. engine is spotless, it probably doesn't have 1200 miles on it since complete overhaul. It sat for years without being ran, but I had left water in the block and freeze plugs rusted out with engines sitting on garage floor. When I got back to the project I tore down the engine and replaced all gaskets and threw in a new set of rings just to be sure, I scuffed bores etc. Seems like it had some blow-by so I then installed pvc. It seemed to be working ok until later on I keep having oil drizzle out of breather when I drive it 15 miles or so and it drips off of trans cover. Breather was on driver side on low end of valve cover, so now i switched it around and put breather on the other side and put pvc on low end. I haven't driven it on the road yet so not sure how that's gonna do. Just playing around with it and found it odd that no suction is being created from breather side. If I blow air through the valve covers I can feel a good flow coming out the other side, but yet even with full manifold vacuum I cannot seem to get suction from breather. I think its still gonna blow oil out even with breather in front. Valve covers have baffles , but I can see oil splatter onto the baffle plate. it is just a flat plate screwed to area below the hole in valve cover. I may have to re engineer the baffles. I bought these valve covers from jc whitney back in the 70s and the baffles may not be exactly as they should be.

 

Just so we are on the same page the pcv valve should be on the passanger side at the back of the valve cover to the back of the block. The breather cap for air intake and oil service should be on the drivers side towards the front of the block. This is how you have yours set up correct. I know you said you have some aftermarket covers but I would assume that they should mount and have holes in somewhat the same postion. Just a little 352 stock setup pictorial.

Hope this helps.

 

OK, I'm with you on your recent valve cover removal and inspection.

Did you look at the valve seals and check the drainbacks while in there?

Those neoprene jobs start to give up the first time you fire the motor. With a low-mile engine that sat, I would not at all be surprised to seem one or more crumbled.

Good luck with it.

 

Agree with poster who said PCV does not open much at idle, they are designed to be open at RPM, when blowby is at its highest. Still there could be something wrong with it. How did you perfoprm the vacuum test on that side?

Try a new, clean, breather cap.