Seeking Advise on Rear Main Seal on 68 440

[AndyFranklin]

Wondering how to diagnose rear main seal is leaking. Prior owner thought it was.

If it is the culprit can it be replace bydropping the transmission or does the engine need to be removed ?

Many Thanks,

Andy

 

[Big_John]

Often, a rear seal leak is misdiagnosed and the problem is actually the oil pressure sender at the rear of the engine block. That leaks and runs down the bellhousing and leeks like the rear seal is leaking.

So, before you do anything, check that. It's not an uncommon spot to leak.

The seal can be replaced in the car with the transmission attached. There's other guys that can advise you better on the nuances of that.

 

[413]

If you have never done a rear main seal on a BB mopar then in the car on your back is a tough learning curve.

Clean it up by pressure washer and Castrol super clean will help your diagnosis. Also won't hurt to have it clean for any tear down or engine removal.

Check pressure sender, valve covers, and back of intake manifold first.

 

[1970FuryConv]

Ditto leaks from valve covers mimicking rear main leak. If you smell oil burning on the exhaust at start or after you drive for 1/2 mile, do valve covers first.

 

[mgm1986]

If you have never done a rear main seal on a BB mopar then in the car on your back is a tough learning curve.

Clean it up by pressure washer and Castrol super clean will help your diagnosis. Also won't hurt to have it clean for any tear down or engine removal.

Check pressure sender, valve covers, and back of intake manifold first.

This is spot on. Especially if it has a rope seal that doesn't want to come out.

Before removing anything major I would definitely follow the advice of these folks and triple check it is the rear main leaking!

 

[Boydsdodge]

I have a suspect rear main leak, but before I do anything more I will try the oil dye after a good cleaning.

 

[St8lypace]

I too thought I had a bad rear main seal, but on the advice of this forum I checked and it turned out to be the oil pressure sending unit. That was quite a relief.

 

[imperialman]

I too thought I had a bad rear main seal, but on the advice of this forum I checked and it turned out to be the oil pressure sending unit. That was quite a relief.

Had I had that amount of luck my purchase after buying a replacement oil sending unit would have been a couple of lottery tickets

 

[AndyFranklin]

I have a suspect rear main leak, but before I do anything more I will try the oil dye after a good cleaning.

What is oil-dye?

 

[Boydsdodge]

I am not endorsing this product, I am just posting an example of what I spoke about. I haven't used it since my helicopter days, but I intend to use it before tearing into the engine.

OIL-GLO® ULTRA Fluorescent Leak Detection Dye

Industrial Leak detection dye for synthetic and petroleum-based fluid systems. Works in closed-loop circulatory systems.

spectroline.com