Intermittent crankcase pressure issues
I'm getting crankcase pressure issues with my freshly rebuilt 318.. I'm getting a little bit of oil in my valve cover breather and out the front of my intake.
I'm not getting an issues at idle or just driving around . It seems to be an issue at high loads + high rpms, I went with a high volume oil pump and a windage tray but stuck with a stock 4 qt oil pan.
I did a hillclimb/cruise a month ago and that seemed to be the worst of it by far. During one of the steeper climbs there was enough oil coming from under the breather to leak onto the headers and cause a small amount of smoke under the hood. Am I on the right track here?
Not computing..... I am trying to figure out how an HV pump can 'flood' anything more than a standard pump, if the pressure relief spring is at the same pressure setting? Once either pump gets to high enough RPM, the pressure limits per the spring, and the flow to the head limits. Not saying there is not oil setting in the heads, but changing the pump is not going to change that... unless you coincidentally go to the lower pressure relief spring.
And maybe I am not seeing something..... I am not seeing how oil around the crank will raise crankcase pressure per se. Or is it just making the air in the crankcase more oil-filled, and thus making the symptoms more noticeable?
This is not an oil-pressure issue.
IMO; It's a drainback issue at high rpm with the car not sitting level and maybe being tossed around from side to side. The HV pump moves a lotta oil and when that oil piles up in the valve covers it runs down to the back of the heads and piles up there waiting for it's turn to escape the heads. If the rear guide seals are not the tightest, oil will get into the chambers with attending smoking out the tailpipes. Now, when the oil finally makes it into the valley and down into the intermediate gear, that spinning oil-flinger fires it out sideways in every direction. Some of the oil makes it to the crank which also fires it out in every direction,vertically now,and aerating it in the process. And the oil-level in the pan is rapidly declining, because the oil is all in suspension getting the beating of it's life.And the piston motion is pushing that slug of aerated oil around like mating Wallruses..
Now, the PCV doesn't function the same at hi-rpm/near zero vacuum as it does in hi-vacuum cruise mode, so it ain't doing much, except maybe venting aerated oil out of the one cover and into the intake. The breather is now pushing blowby out onto the valve cover, and it too may be overloaded and pumping oil.
Yeah so maybe the rings ain't helping either; but blowby can't be eliminated, and a hill-climb is a sustained hi-rpm event, many times more strenuous than a drag-race.
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I cured my rally-cross problems by cutting drainage channels in my soft aluminum heads, by drilling the valley pockets, by running just 5 quarts in my 7 qt roadrace pan, by re-engineering my breather system,and by disconnecting the pan E-vacs for the event..
I already had the deep-pan and the fresh-broke-in Moly rings, with almost immeasurable Leak-down, and almost immeasurable Blowby on the gauge. And; I was running very high cranking cylinder pressure, about 11/1Scr and as I recall over 185psi.
I left the HV pump on there, as I had previously drilled out all the passages to accommodate it; and I had no intention of loosing any more rods,lol; Cuz you know I don't always shift when the power peaks lol.Sometimes I stretch ...... it.............. out................ a .............. lil.........bit. I mean if it's still spinning or pulling and I'm winning and I just need another 50ft, what the heck is the difference! I'll loose less time stretching than shifting.
>Actually, I don't think the engine has a problem at all. Other than a baffle/breather issue, and possibly a poor seal at the front of the intake.
If it was mine,I would re-engineer those and then;
I would plumb a lo-pressure gauge to the dipstick tube with a long hose and put the gauge where I could see it from the driver's seat. Then take it for a roadtest.
If the gauge showed more than 4 psi, I would tear it all apart looking for the problem. That's HotRodding.
But if less than 4psi,and it still had a problem, I would install a 7qt or more roadrace pan and run it a qt or two short of full.
That's what I would do, er did.
