Need Help On Excessive Crankcase Pressure

[1969 beep beep]

I currently completed a 499 stroker build, and I have been having problems with oil coming out of my mopar distributor. The car runs excellent. Under wot oil is blowing out of the bottom hole under the distributor. The distributor has roughly 2000 miles on it and was installed on another engine that never had a problem with oil leaking out of the distributor. I tried shimming the end play but made no difference. I can drive the car around normal and no leaks, as soon as I start driving it hard oil comes out of the bottom of the distributor. I believe it is from excessive crankcase pressure. I did a compression check and the highest reading was 200 and the lowest was 193. Not sure what else to do. I am running a pcv on one valve cover and breather hooked up to my factory air grabber air cleaner. Any ideas.

 

[daredevil]

Is there an o ring on the bottom? Usually oil right there is an intake end gasket leak

 

[1969 beep beep]

Yes there is an oring. It is not coming out from the base it is blowing out of one of the holes out of the two under the distributor weights.

 

[Sixer]

Likely you've enough pressure to overload the PCV-which was designed to work with the original CI displacement and rpm range. Time to can it and go with breathers only. The PCV flows almost nothing at WOT, and all that blowby has to go somewhere. Doesn't have to be excessive to overwhelm the system.

 

[67 coronet]

sixer is correct.how many rpms are we talking when you say driving hard?on most of my race eng(the ones i dont have crank evac hooked to exahaust)i will use high flow open breathers like k&n's.

 

[daredevil]

Usually they blow it out the dipstick. Never seen it thru the distributor. Locking dipstick?

 

[70rr-brian]

sixer is correct.how many rpms are we talking when you say driving hard?on most of my race eng(the ones i dont have crank evac hooked to exahaust)i will use high flow open breathers like k&n's.

What he said... If you are doing a lot of full throttle runs either go breathers on both covers and plan to clean up oil mist from time to time or use a header evac system.

 

[1969 beep beep]

Thanks guys for the feedback. The dipstick is just the push in style. None of the gaskets are leaking except for a very small amount from the valve covers. So far the rear main seal is ok. Are there any other recommendations on good breathers besides K&N? I see some have small holes on the underside of the breather. Will this be enough or should I go with the open K&N style. I would think the K&N style will vent more volume of air. How much oil mist are we talking? It is street driven and usually rpms don't go over 5500rpm that is what a meant by driving it hard. Will there be any problems with leaving it with the pcv setup? Beside the oil leaking from the distributor.

 

[Stumper]

I've been waiting for someone else to say it ... but i have never seen oil leak from where you are describing - high pressure or not. Without seeing pictures and maybe understanding better I am suspecting some seal within the distributor itself. If you had high crank pressures I would think you would see leaks in the typical areas first??

 

[1969 beep beep]

Stumper, I know I have never seen this either. I shimmed the end play from the factory .023th to .007th. Made no difference. The first pick on the left of the distributor base is were the oil is sitting. You cannot see it now because I cleaned it up. I usually find a teaspoon of oil there that will run down the fuel pump side. I first thought it was the o-ring When I removed the distributor and disassembled it I found oil in the distributor and you could see the oil was leaking out of the lower hole on the underside of the large distributor area. The other pic is my drivers side setup.



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The pcv is on the passenger side valve cover going to the carb with a 3/8 hose.

 

[RustyRatRod]

You've not said and no one has asked, but how new is this engine? How many miles?

 

[1969 beep beep]

The engine has 700 miles on it. The start up was done on an engine dyno. After 5 dyno pulls, I noticed a small tear drop of oil in the same place. I babied it for the first 500 miles, then after 500 miles I started taking it to 5500 rpm, and that is when I started to see a lot more oil. So it looks like it only happens under wot.

 

[Stumper]

So the oil is puddling on the block in the pocket to the left of the distributor collar but it's definitely coming "out" of the distributor?? That's the part that confuses me. I've never seen oil up in the distributor before (although I am not seasoned expert either).
For shits and giggles I would double check that you are not getting oil blowing out from the front edge of the valley pan - or even upper side of the valve cover and somehow making it appear to be in the distributor?

 

[Sixer]

This motor time out good? There is no seal in the distributor. Keeper below the housing on the shaft, a thrust washer, another thrust washer on top, and thats pretty much it. Only a badly worn shaft/bushing could allow that much up there, and even then I can't see it being that much. I like the alternate source theory espoused by the distinguished representative from NC.

 

[RustyRatRod]

So it's possible the rings ain't even broken in. If that's the case, it'll have some blowby. Give it some time and see what it does.

At any rate, it's GONNA have more blowby regardless. More compression=more blowby and it sounds like you have a lot of cylinder pressure. If it doesn't clear up, you may need to go to the header style evac system already mentioned. That would provide vacuum exponentially as RPM increases, instead of dropping off with RPM like a vacuum operated PCV.

The engine has 700 miles on it. The start up was done on an engine dyno. After 5 dyno pulls, I noticed a small tear drop of oil in the same place. I babied it for the first 500 miles, then after 500 miles I started taking it to 5500 rpm, and that is when I started to see a lot more oil. So it looks like it only happens under wot.

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Only a badly worn shaft/bushing could allow that much up there..........

THIS ^^^^^^^ could also be a problem.

 

[70rr-brian]

As mentioned it may not even be a pressure issue. But you could ditch the PCV and throw in a couple breathers (one each side) and see if the leak lessens or disppears entirely. If it does then you know. Just make sure you have baffles under the breathers or you will ruin the breather in short order and have a mess on your hands even faster. As far as oil misting....I would say a good wipedown will be in order about once every couple of weeks depending on how much you drive it.

 

[Budnicks]

They make an "Outerwear" sock/wrap you could put on/over the K&N breathers also, cut down on dirt & misting... I too have never seen an oil leak up-thru the distributor, under it yes {bad o-ring}, even on a 526ci Blown PSI Screw type blower over driven 50% & 15:1 compression w/Molly & stainless rings, alky/methanol injected race engine, spinning 8500+rpm, with some serious oil pressure & crank case pressure... leaky/weeping cylinder head gasket in that corner, valley pan or corner of intake seal, valve cover gasket, some pin hole in a casting somewhere maybe other possibilities, I'm not saying it couldn't be, coming up thru the distributor, but I've never seen it either... If your running at WOT for long periods of time, kind of doubtful thou, but a vacuum pump will cure the issue of any ring blow by/pressure in the block...

 

[1969 beep beep]

Guys, I just do not understand how oil is blowing up threw a .007th gap on the trust washer and blowing up the distributor shaft, when it can blow out of a seal much easier. I can not see anything in the corner of the valley pan and nothing in the corner of the valve cover. I originally took apart the distributor and it had a teaspoon of oil in it. I am running manifolds and mufflers so I will not be able to run the evac setup. I put a new pcv on it and I am going to try it. I also disconnected the hose of the air cleaner and just have it sitting on the inner fender. I am going to hopefully try it tomorrow. If I still have oil in that area I am going to pull the distributor and take some pics. How much more can I shim the end play, I only have .007th left?

 

[Sixer]

Don't bother-won't help and too tight will just wear the housing or the shaft retainer. Just as a thought, check for oil in the breather hose (not the pcv hose). Excessive blow-by motors will often push oil mist up into that hose.

 

[67 coronet]

if your current idea wont fix it, you could add some oil dye and do a single high rpm run.then look at it with a dye light to see exactly were the oil is comming from.