Help!!....blowing excessive oil thru PCV

MarineMustanger

Registered User
I am blowing WAY too much oil thru the PCV into the intake manifold. It really only occurs under full throttle acceleration under ful boost (13psi). This started after engine rebuild when I had to take my valve cover breather hole baffles out because of the larger roller rockers (engine has head porting, cam regrind, etc. I have all the MP intake goodies, exhaust, etc.

I've put filters on both breather lines, and it still pushes/sucks oil thru the pcv valve, 2 filters and into the intake plenum. It will suck in a quart in a few hundred miles if I get down on it a lot.

I tried to reroute the pcv valve/hose to the intake air filter box instead of the intake, in hopes that it won't suck as much in, but when I did a full throttle run, the pressure in the crankcase pushed the dipstick up enough to allow oil to shout out of it and it sprayed the driver's side of my engine compartment.

I've been dealing with this since August!.....this"little" problem is really getting on my nerves....anyone want an SC????!!!

Thanks
 
J.C. do you actually mean through the PCV vavle or it's vent on the drivers side valve cover? If through the PCV valve have you tried a Motorcraft SC specific valve? They are different and seal better.

You have excessive crankcase pressure, see my FAQ at the TBSCEC on boost leaks and note the admit by Fred. This may help you locate the cause. You may actually have a situation like I did on my 3.8 Mustang recently. While porting the heads I accidently cut through the port and into the rocker area just barely. It was behind the pushrod tube in a center port and I had to use a flashlight in the port to see it from the outside. The car went through oil just as fast but since it is a four barrel car it never blew pressure out, just sucked oil and crankcase gasses in. A misaligned intake gasket would cause the same thing. I have a feeling you have an extraordinary problem like this. Mine was just as fustraiting to deal with.

Just thinking, if it is due to your PCV valve not having a baffle under it anymore and nothing else you may have to relocate it. Such as in the top of the filler cap like on old Chryslers.

Vernon
 
I could be wrong (and somebody please correct me if I am) but if you're building enough pressure in the oiling system to pop the dipstick out and blow oil all over.....then I'd suggest that that you have a pretty bad leak from the combustion chamber somewhere. I say this because it is the only place I can think of that would produce enough pressure, especially under boost. Maybe do a compression and leak down test on all the cylinders cause it could be a bad ring or even a bad valve guide. Just my .02
 
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Oh and one more thing, the cylinder on my Mustang that had the ventilated intake port was constantly oil fouling because of it. Do you have one or more plugs constantly going foul?

Vernon
 
I initially did, but that is (I believe) because I was sucking in so much oil, thru the PCV valve, intake plenum and into the cylinders. I know am sucking it in because there would be oil pooled at the bottom blade of the throttle body, as well as oil in the back of the intake plenum (when I looked in thru the TB), and dripping out of the hole where the pcv hose connects to the intake plenum (again, looking in thru the TB).

I get great gas mileage on trips (25-26 mpg) and have no problems with idling, etc.

This is continues to frustrate me......I think I will do a compression and leak down test.
 
I had a similar problem....

Started right after I put a hole in one of the pistons at the drag strip. Started spraying oil out of the breather. Found another piston that was cracked. Check for leakdown...
 
I know it sounds bad but when I blew my engine it had same sort of problem, quite a bit more extreme though. I had broken the ring lands on two of my pistons and it blew the dip stick out and covered my engine with oil about 3/4 track, hate when people do that, even worse when you do it yourself. Sounds like you have some sort of similar problem with you pressurerizing the crankcase. Maybe you nicked a compression ring or something when it was built, pretty easy to do if you don't really pay attention. May be something less serious but I thought I would throw it out.
 
I pulled the pcv out of the valve cover while it was idling and felt for pressure and didn't feel anything, even when I reved it. I did have a lot of suction from the pcv and hose connected into the inlet plenum, enough to suck in oil.

This is realy starting to irritate me. The only time it forced up the dipstick was when I had the pcv disconnected from the inlet plenum and routed to my air box, in hopes of reducing the amount of oil sucked into the intake.

If I had a leak in the combustion chamber (ring, valve seat, head gasket) wouldn't I feel pressure out of the crankcase?

Do you think it would only do it under full boost?
 
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