Large oil leak 21 stud motor

Adam/Mill Valley CA

Adam/Mill Valley CA

Senior Member
I just finished installing my newly rebuilt ****** (which works fine)on my '36 pickup -it had been sitting for about 6 -8 weeks. It has developed a massive (>1 quart in 35 miles) oil leak now from the cotter-pin hole at the back of the oil pan; this is completely new (it always seeped a little bit from the front rope seal). I did remove the clutch to check the flywheel runout(which was fine) but that's as close as I got to the engine itself. I know these babbitt-bearing motors don't have an actual rear main seal. There's nothing I can see leaking from the top of the motor. Any ideas as to what might be going on?

Adam
 
Hi Adam;

WOW, Strange things happen.

If it is engine oil leaking from the cotter pin hole, it is coming from the rear main "seal" area, the rear part of the pan gasket. the rear galley plug or the oil pump drive cover.


If you did not disturb any of that stuff, it is a mystery that it did not leak before and leaks now. In any case, It looks like you may have to have to pull the pan too get to the problem.

Look real carefully and be sure it is not the oil pressure connection at the rear of the block that is leaking around the back of the flywheel area and dripping off the cotter pin itself.

Think about what you did disturb and may be you can come up with better posabilities.

Just my thoughts,

Chris
 
Thanks,Chris; I'm obviously going to have to pull the pan. When you say "oil pressure connection at the rear of the block" you mean the port for the oil pressure gauge on the driver's side rear, correct? I did look there, it's not leaking

Adam
 
[QUOTEWhen you say "oil pressure connection at the rear of the block" you mean the port for the oil pressure gauge on the driver's side rear, correct? I did look there, it's not leaking

Adam[/QUOTE]

Yes, That is about the only place on the external part that the rear of the block that may be a problem. It could be at ther rear of the intake manifold or oil fill/fuel pump adaptor but I am sure you already have looked there.
I am sure you have already done so but just be sure the leak is not from some where else and running down an dripping off the cotter pin and not actually coming from inside the clutch/flywheel area.

Be sure to let us know what you find out.

Chris
 
I did check those areas. Also put a mechanical gauge on the block, it shows #40 cold (which about all this engine has ever had) and so I don't imagine an oil galley plug could have let go. I will get under it to be sure it's not coming from up front of the pan, although it doesn't look like it. Also, the clutch started to slip at the end of the drive (it was perfect before) so I think it's getting oil soaked.
 
Adam/Mill Valley CA said:
I did check those areas. Also put a mechanical gauge on the block, it shows #40 cold
Also, the clutch started to slip at the end of the drive (it was perfect before) so I think it's getting oil soaked.
Click to expand...

It sounds like you are on the right track.

Actually, I would expect a little more oil pressure then 40 # cold.

Keep us posted,

Chris
 
You didn't put too much oil in the pan did you?? That's the main reason for oil comming out of the cotter pin. G.M.
 
I would guess that the oil could be coming from the oil pump gear cover or the galley plug, since it is coming out the cotter pin hole. I had a similar problem with my 21 stud this spring when I made the discovery that the front galley plug was not installed. The leakage there caused 0 oil pressure and it all just leaked back into the pan from behind the timing gear.
Once you drop the pan you will likely spot the problem right away.
-Lyndon
 
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