33 Rear Main Leak
 

Hello. I have a 1933 Fordor that is leaking/pouring out a significant amount of oil out of the rear when running. I read a lot about the rear main leak on early motors. I first drained the oil and filled it with 4 quarts. The leak seemed to continue to be constant. I then dropped the oil pan to inspect the cork gasket, determine if there was possible sludge in the oil pan and to see whether the rear main bearing had a tube. After dropping the pan, I can see that the cork was present and there is a tube coming off the rear main. I have a few questions that I was hoping someone could help answer. First, is the tube in the attached photo correct? Second, does the block look correct for '33? I am wondering whether the hole the bottom-front-left of the block is correct? I also want to make sure I have the correct oil pan for this block (the oil pan I have is from a '33-34). Third, is there anything else I should be checking? Any ideas/help would be greatly appreciated.

Re: 33 Rear Main Leak
 

Tube is not factory .
Make sure the fitting at the top of it is not screwed in too far .
If it is it will act as a dam and cause a major leak .
I have found 5 turns in is safe .
Also make sure the tube is clear .
I would cut it's tail off so it is straight down and just into the oil .
Should be 5 qts - not 4 .

Oil pump is newer .
How much oil pressure ?
Too much volume will cause a leak .

Block is no older than 35 .
What is the spacing on the main cap studs ?
It is vented [ the hole you mention ] .

Oil pan looks proper .

The oil pump drive gear cover can also cause your problem .

What are you using for intake-fuel pump stand and breather on to of oil tube ?
If you are using a 35-up intake and the tube under the fuel pump stand that is a bad idea with a 33-34 oil pan .

Re: 33 Rear Main Leak
 

Back pressure could well be a problem.

Re: 33 Rear Main Leak
 

Hi David, I'm a Model A guy getting acquainted with early V8s.

I will remove the tube and check for blockage and cut it down. I don't know the pressure on the pump, but your points are well taken. I will get the spacing on the main cap studs.

Attached are photos of the intake and fuel pump stand. Not sure what is correct for this block.

Re: 33 Rear Main Leak
 

Your intake setup is 34 .

That said there is a early 35 intake that looks like yours .
The way to tell is the hole under the fuel pump stand is round to accept the tube that fits into the block on vented motors .
If yours is round and has a pipe in it take the pipe out as it will make a mess .
If the hole is diamond shaped you can eliminate this as a cause .

Re: 33 Rear Main Leak
 

With respect, David, it is an un-vented block and therefore it is older than '35 and since it is not a '32 block, that leaves either '33 or '34.

Re: 33 Rear Main Leak
 

First 2 pics are a 33 motor first showing the non-vented rf area .Second pic is the same 33 motor with drain tube and forged crank .
Last pic is a 35 motor .

Compare to the OP's last pic
Just took these in the basement .

Re: 33 Rear Main Leak
 

Hey David - take a closer look on his first post - it appears to have the triangular vent on the bottom/front of the block.

Re: 33 Rear Main Leak
 

If that is a vent, would you need to use a 35 or later oil pan for purposes of venting the motor? Would having the incorrect oil pan possibly force oil out the rear slinger?

Re: 33 Rear Main Leak
 

Oops! Time for new glasses; sorry.

Re: 33 Rear Main Leak
 

No , look at post 5 and tell us what you find .

Re: 33 Rear Main Leak
 

Too much clearance in the rear main bearing.

Re: 33 Rear Main Leak
 

while i am no expert, here's my hillbilly thoughts. first, its got the vent hole in the block, so should have the vented pan. we have'nt seen seen the front of the block yet, so could even be later than 35 if the water pump block off plates are there. doesnt matter really, if it has the vent hole in the block i believe it should have a vented pan. hard to argue 33's with david j, but i see no reason that the intake manifold should matter. i believe the pan vent was introduced in 35 to make the road draft vacuum pull the oil vapors out the bottom and reduce oil smell in the car. so if it has a diamond shaped port under the fuel pump stand, 33-34, the tube to connect the the 35&up draft system wont be there. the tube was to keep the draft going past the lifter galley and down to main crankcase where all the action is.massive turbulence going on there, which could push oil out the rear main, so good place to have a vent. so, we know its not the original motor, but my thought is whoever changed it most likely put the old manifold back on to make it look correct, or because the carb was good and all the connections then went on without issues. so...now we get on to ken with the cool zepher coupe, he's got a point about rear main clearance. since the pan is off already, i would pull the rear main and check it. first, you may be lucky and its an lb motor. either way i would first check with a dial indicator to see if the crank is round, i think a half a thou is spec by memory, and then support the crank with a bottle jack and do a plastigauge check to see what the overall clearance is. if your results show an out of round crank, i would still fool around with the shims (if its a babbot motor) to snug it up a bit. one of my model a's has a bad crank and i tightened it up as best i could 20k miles ago. still has an occasional main knock, but i expect many more miles yet

Re: 33 Rear Main Leak
 

I recently pulled the pan on my '33 V8 to clean the sludge out and don't recall seeing a white color tube hanging down. I don't have any serious oil leaks and great oil pressure. The engine was rebuilt years ago and runs great. Is the white tube really necessary? Maybe my memory is failing me (again) - I wouldn't be surprised.

Re: 33 Rear Main Leak
 

Thank you for all the comments, very much appreciated. I will pull the fuel stand and remove/cut the tube and look at the oil pump closer and return with what I find. From what I've read so far, it doesn't sound like these motors used shims although it wouldn't be a bad idea to check because there's always that possibility. It would also be a good opportunity to plastigauge the rear main depending on what I find with the fuel stand, tube and pump.

Re: 33 Rear Main Leak
 

That white rubber tube and the brass fitting are something that somebody installed - it is not original. The original tube was metal. I can't see it being an issue, unless they threaded the brass fitting too far into the cap and ended up making it hard for the oil to drain back to the pan.

Re: 33 Rear Main Leak
 

As CAS3 noted, if you're going to do a plastigauge check in the car, you need to support the crankshaft (put a bit of pressure on it to hold it up) - otherwise the weight of it will crush the plastigauge. Wipe all oil off the cap bearing surface as well. Obviously this isn't the best measurement method (but Hey, the engine is in the car), but it might help you diagnose the situation (if you find large clearances).

Re: 33 Rear Main Leak
 

Ken, glad you mentioned this. Case in point, one of my '33/34 buddies', had a situation of LARGE amounts of oil coming out the rear. Like a quart in less than 50 miles. The reason... the babbitt had 'gone-away' on the rear main. There was HUGE rear main clearance. Amazingly, the engine sounded fine and ran good.

Re: 33 Rear Main Leak
 

The original tube was metal and larger in diameter, the fitting in there now looks like coarse pipe thread, the hole has been retapped so original probably won't fit

Re: 33 Rear Main Leak
 

A little clarity ,
The center pic in post 7 shows a stock 33 motor with the right oil pump and NOS drain pipe .
Good idea to use one .

The use of 33-34 oil pans on 35-36 blocks is common and does not cause problems if done right .
That equates to not having the breather pipe under the fuel pump stand .

Isn't the oil cap on 35's an air scoop ?

The oil pump drive gear cover gasket can cause your issue also .

The reason I asked for the spacing on the main studs is that will tell us if it is babbit or insert mains .
No shims on babbit mains .

Simple way to check for excessive rear main clearance is GENTLY jack up on the flywheel and see how much movement you get .
Simply hold something against the crank and main cap in the up position and let it down . Crude but it should work .

Let us know on the breather tube and oil drainback tube .
This is first order of business here .