I'm struggling with my new 500cid low deck stroker moror. I have a big oil pan leak from the front right corner and in the area of the rear main seal retainer. The Engine is equipped with a Milodoon Road race pan (part# 31580) and a windage tray. Frist thing I checked was if it leaked from the rear main seal but nothing comes out that way.
I have checked alignment and height of both front timing cover and rear mail seal retainer and that seem to be ok. I have used gaskets from Superformance two times now, once dry and once with small amount of High temp RTV where the timing cover meets the block and the same with the rear seal retainer. The pan is not warped and is 100% flat. As soon as the engine gets warm and gets reved above 3000rpm it starts leaking.
I'm running an open air filter style valve cover breathers on both vale covers but it still shows signs of crank case pressure with the deep stick raising out of it's tube. When I rev the hot engine without the breather I feel a slight pressure coming out of the breather grommet in the valve cover. The engine is freshly built professionally so I'm doubtful to piston ring blow by.

The oil leak is driving me crazy and I wonder if there is anything I could I have missed out? I consider trying to set it up with a vacuum pump, thoughts on that for a street motor?

A "slight" pressure is ok, but it sounds like you have too much blow-by if the dip stick tube is venting with the valve covers vented also. I would run a leak-down test next. Then maybe put a few miles on it and run the test again to see if there are any changes. Excessive blow-by could just be because the motor is new. A pan oil leak would occur all the time - although more excessive at higher RPM.

Concider a better breather set up,or better than that,,,,,,an electric vacume pump to relieive the crank case pressure.

It isn't unusual for big stroker motors to have a lot of crankcase pressure. Even if the rings have sealed up the bottoms of the pistons are pumping a lot more air in a stroker than they did in a stock engine.

One the dyno I usually use large #12 AN breathers on each valve cover. If the oil pan is restrictive then the air doesn't have anywhere to go and it builds up pressure. Pushing out the dipstick is a sure sign of a lot of crankcase pressure.

You can measure the blow by with the engine running just to see how much you have. You can also do a leak down test and a compression test if you think the rings haven't sealed up.

I run a electric air pump on mine out of a S-10 pick-up.

New motors may take a while for the rings to seal up well Did the block have a torque plate on it when honed? If not it may take longer for the rings to seat On my 511 and 518 C.I. 400 stroker motors I ended up with two PCV and two breathers, one each on both valve covers

Before you start looking at a crankcase vacuum system, verify you don't have a blow-by problem. With both valve covers vented, you should not be blowing the dip stick out of the tube @ 3K, even on a big incher.

Andy knows more than most, So I read his post and would tend to put a lot of weight in his words. With that said, enough blow by to push the dipstick out of the tube, coupled with RPM related oil leaks at the pan gasket, do not seem to be a good signs to me. Considering 500 cubes in a lowdeck generally means fairly short pistons, I'd be tempted to pull it and ask the builder to tear it down and take a real good look at the rings & skirts for evidence of anything unusual that could have happened upon initial start or break-in. ???.... your choice may vary.

Good luck! and keep us posted.

Having an intake vent and a PVC valve on both covers would just vent the area directly below the covers. The idea is to pull outside air from the valve cover with the intake vent, through the crankcase and out the PVC valve on the opposite valve cover using manifold vacuum.

I would think excessive blowby is your problem.

Is this a race only car or a street driven car ? Ron

it sounds like you have too much blow-by

X2

In this months issue of engine professional there is a good article on an adjustable p.v.c. M/E Wagner makes an adjustable valve that looks good. You might give them a try.

Thanks a lot for sharing knowledge! I will do a proper leak down test to check blow by. With two open air filter style breathers that have no resistance when I blow through them I doubt that I do not have proper enough crank case ventilation. I guess if all cylinders is within 10-15% leak down I have to go down the path of installing a vacuum pump.
This car / engine are only street driven is there anything I need to consider regarding vacuum pump choice or installation?

My 63 is a 99% street car and I just ran these vented breathers as the hose just runs to the back of the eng in case they would spit a little oil it would not go on the valve covers. But it does not vent any oil out of the valve cover breathers as I dont have much blowby. And since my car is mostly a street car I went back to a PCV system for the street. It pulls enough vacum to work the PCV valve. And when I go racing I hook both breathers back up since the PCV dont vent the crankcase much at wide open throttle. The PCV system works nice on a street car pulling any excess crankcase vapors out and burning them in the eng combustion chambers. Dont have any eng pics with the PCV hooked up yet. Gotta take a few soon. Ron

Check the breathers first... see if you can blow
through them... I bought a pair of chrome Summit
ones that I could barely get air through... I pulled
part of the stuffing out and bent the loovers open more
(blow from the oil side)

What is your static compression ratio? If you have detonation due to too high a compression ratio for fuel octane and air temp you'll get a whole bunch of crankcase pressure from that too. Or that is the 'experts' evaluation/guess to my former motor Hard/expensive lesson learned. I have a Milodon 31151 pan as well but does the 31580 have a divider/seal plate between the bottom of the engine crankcase and pan top? I wonder about the pistons pushing air against that pan plate? Have a brand new vacuum pump assy waiting on new 493" motor (with lower compression) and new header combo.

Are you certain that your RR oil pan flange is not dimpled or otherwise distorted? I've this same pan and found that torquing to recommended 15 pounds will grossly distort this flimsy/poorly designed flange.

I've posted before photos of my own little fix. If pan flange is damaged you will first require surgery to repair,,,hopefully successful. Once damaged and repaired, the metal has been compromised and will distort easier.

Used 1 inch wide by 1/8 inch thick steel stock, available at any hardware store.

Resolved my issues and all is well.

A major side benefit is with proper torquing, I am not required to use any silicone goop,,,I do use a bit at rear main seal retainer for insurance,,,makes for a much simpler oil pan RR next time.

I am aware that someone supplies a gasket with steel inserts or some such design at the bolt holes to help eliminate this distortion. I know available for Chevy(in fact I think factory built uses such), have not checked for Mopar.

Nice job. I like those.

Installed in car.

that happened to me when i removed my PCV valve. started blowing oil out the front right corner of the oil pan. put the PCV back in and it stopped.