crankcase evacuation?

[moparmade43]

I've got a 75 duster with a stroked 416 that has only 100 miles on it. I assembled it myself, and the engine has edelbrock heads, ported, air gap intake, hydraulic roller cam .550/.570 lift, 236 @ .050 duration, 10.3 compression. I have a Vato Zone el cheapo chrome breather on one valve cover, and a pcv valve on the opposite to the intake manifold vacuum fitting. My question is, how do you know if you are getting good low pressure or even vacuum in your crankcase? My "problem" is that while driving the car for break in, (still have the hood off), I noticed a little bit of oil on the windshield. On the passenger's side, where I have the breather. Not a lot, but it looked like a fine misting. The only leak I have (other than my drain plug, which I had to replace) is the rear main seal (which is another aggravating subject in itself). Now, the thing that is confusing me is that I don't have any oil that I can see leaking out of the breather, when you take it off and look the foam still looks whitish underneath, the dipstick is not pushing out, and it is not a locking dipstick, and the pcv valve grommet is not really held in that tightly, and it is not leaking or blowing out. Does anyone have any ideas to check this. The car is an absolute brute on the street, and I would think if I had appreciable leakby, or a ring didn't seat or something, that I would have a worse situation than I have going on, but I am not an expert by any means. I just can't pinpoint where the small misting is coming from and I really don't want oil on my hood. Maybe the rings aren't completely broken in yet? Oh, and I have baffles under all my valve cover "openings". Any feedback or opinions would be greatly appreciated. Final thought, I am gonna do a leak down test eventually (I always do on any new engine to get a baseline)

 

[dustinmoran91]

Check your oil pressure gauge fitting. Maybe the brass is cracked or theres a tiny hole rubbed into the line?

 

[DJVCUDA]

what oil pan gasket did you use?

 

[moparmade43]

Will check the oil pressure sender again but I didn't see any oil on the distributor clamp or there. The oil pan gasket is a milidon "tear free" gasket I believe, and it doesn't appear to be leaking on the rails or the front, I put it up on the lift and let it run for a while, the only leaking I see is coming down from behind the engine, main seal most likely

 

[OldmanRick]

How does the tunnel and frt. floor pans look,,,,misted oil there also? At speed, any leak will get blown all around and in your case with the hood off is magnifing that. You have a known leak, rr main?, and if your leakdown verifies good, i think that's your issue.

 

[moparmade43]

Yeah and that is very possible. The only reason I was thinking about it coming out of the breather is that it has only been on the right side of the windshield so far, not the left, and not on the firewall at all that I can tell. I just was thinking that with the 4" stroke crank and no windage tray that I was possibly building up more crankcase pressure than with a factory crank and tray. I will just keep checking things out to see if I can narrow it down. Thanks for the help

 

[Lonewolf3165]

Get a PCV grommet that fits the V.C. & the valve snugly, otherwise you're not developing enough negative pressure(vacuum) in the crankcase because the air is just getting sucked in around the grommet instead of pulling it through the crankcase. It needs to be able to pull air through the whole system from the breather on the opposite side in order to properly evacuate the crankcase. This could very well be the cause of your main seal leak problem too. Seal that PCV up good & your problems will probably go away.

If you want to check the efficiency of the system pull the dipstick & connect a vacuum gauge to the tube, block off the breather & check vacuum. This should be a quick check not a prolonged experiment because you don't want to suck the seals/ gaskets inward if its working right. You should see something close to manifold vacuum at the gauge. Next do the same at the breather hole w/ the dipstick back in place. Same thing.

 

[moparmade43]

Ok, I had some time to play with the car friday night and here's what I found. First, I took the breather out and stole the oil fill cap off my challenger and put it in the valve cover instead. Then, I made sure the other valve cover fill cap was tight, and the pcv was as snug as it could be. (The pcv valve is not loose in there, but not extremely tight either). Then, I took my vacuum gauge and put the funnel attachment snugly down in the dipstick tube and showed atmospheric pressure only at idle, no positive pressure or any vacuum. I verified the gauge worked, only slight blowing and sucking on the fitting moved the needle. Then, as I held it in the tube, I revved the engine up to 3-4000 rpm repeatedly and held it there for a few seconds, and no change on the gauge, only atmospheric pressure. Now, obviously the engine wasn't under load like it is when you are driving it, but that's the best I could do for now. So, I am assuming that I do not have any major positive build up going on in the crankcase. I verified the same procedure with the 383 in my chrysler and had the same results. I figured I would have a little vacuum but instead did not have any, although no positive pressure either. Final note, the pcv was sucking good, I checked it later, and my idle vacuum through the pcv hose was 7", but with that big cam I didn't figure it would be any better. Any thoughts?

 

[OwdKasd]

I would have to guess that the known leak is to blame. Get The rear main sorted and retest. Sounds like your original breather setup was good except the loose fitting PCV grommet. I would fix the grommet and put the breather back in the way it all was.
With the hood off, who knows where that rear main oil is going to blow??