1936 flathead v8 21 stud oil pan leak
 

My oil pan is leaking oil from what looks like a manufactured hole. I'm not if there is a plug or something missing. New caskets where put on it is from the side of the pan
Thoughts

Re: 1936 flathead v8 21 stud oil pan leak
 

There should be plugs (sometimes called freeze plugs) in four location (two each side) of the oil pan mating surface on the bottom of the block. Sometimes these corrode through if they have been in there a while. However, these are into the water jacket and should not leak oil.

Re: 1936 flathead v8 21 stud oil pan leak
 

If the oil is draining out of the spot where there is a cotter pin, chances are a rear seal failure

Re: 1936 flathead v8 21 stud oil pan leak
 

Ok, if were referring to the bellhousing part of the oil pan that's a different issue. There is not a rear seal per say, it is an air gap/slinger type of seal. A number of things can lead to an oil leak in that area. Among them (the easy stuff) is over filling the engine with oil or something causing increased internal pressure within the engine.

Re: 1936 flathead v8 21 stud oil pan leak
 

where is the hole? picture?

Re: 1936 flathead v8 21 stud oil pan leak
 

Attachment 320332
I put that black little rubber piece to cover up hole it didn't work this picture is looking from the back to front of engine the plug is the front side


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Re: 1936 flathead v8 21 stud oil pan leak
 

That is a vent for the engine. It should not be blocked but it should not leak oil. Under the intake manifold is an additional vent tube just above the oil pan vent. It is possible the tube is not in place this would cause a big leak. You may have to remove the intake manifold to see what is going on. In the photo below you can see the top of the vent tube in the engine valley front of the block.

Re: 1936 flathead v8 21 stud oil pan leak
 

Could be the wrong pan gasket.I had the same problem.As I said,it COULD be.

Re: 1936 flathead v8 21 stud oil pan leak
 

Yes don't block that vent in the pan unless you have made some sort of PCV setup. I would say you have a front seal leak that's all.

Re: 1936 flathead v8 21 stud oil pan leak
 

This is a far out possibility, but are you certain that you have a '36 block? If by chance that's a pre 35 block, without the ventilation features introduced in '35, using a '35 or later oil pan and gasket would allow oil to come out of the lower vent opening.

Re: 1936 flathead v8 21 stud oil pan leak
 

35-48 had this, it's for crank case ventilation. 4 quarts no filter and 5 quarts with oil filter. It's possible you might be missing the tube under the intake manifold or have a hole in it allowing oil to pass through.

Re: 1936 flathead v8 21 stud oil pan leak
 

I also noticed the bolt just above the crank case vent on your pan is wet with oil. Your pan gasket looks pretty wet with oil aswell. Looks like the leak is coming from "above" at the gasket. Is it possible you have to much oil in it? 4 quarts for non canister filtered flatheads and 5 quarts with the filter.

Re: 1936 flathead v8 21 stud oil pan leak
 

Also when was the last time the pan was off? Just pulled mine a week ago and had a quart of sludge in it. (My engine sat for decades) I'd change the oil, add 4 quarts and it would be a quart overfilled. I pulled the pan and cleaned out atleast a quart of sludge buildup. Sludge is muddy and wont drain out when changing the oil. Gotta pull the pan to clean it out.

Re: 1936 flathead v8 21 stud oil pan leak
 

So I think you are right the casket I was sent did not cover a small triangular hole. I looked at pictures I took and saw another gasket that the cork surrounded the area mine didn't

I really hate to take the engine out to just change the oil pan gasket bummer



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Re: 1936 flathead v8 21 stud oil pan leak
 

First, welcome to the 'Barn. Search the forum for posts about pulling your pan without pulling the engine. It can be sone. Good luck. Mike