Tackling a rear end leak

[JonathanC]

There are a couple of drips in the drivetrain of my '41 Chrysler Royal (34,000 miles), one at the diff and one seemingly somewhere near the transmission (Fluid Drive/M-4 Vacamatic).

 

Tackling the rear end first (because far more drops have dripped from it), I have been reading up and checking the service manual to see what's there that might be the culprit. There's a pinion seal on the driveshaft side (#19 in the diagram), and "axle drive shaft oil washers" (#3), as well as a differential carrier gasket (not shown in this diagram but in another one I have in a hard copy). I've also seen mention that there's a breather that could be expelling oil so it may not be a seal at all.

 

What are the group's wisdom/experience on procedure here to get at root cause and make a plan for remediation?

 

If I'm going into rear end work, at the car's mileage does it make any sense to plan to replace bearings or anything else while I'm at it?

 

Thanks

[Adam H P15 D30]

Is it leaking at the axle tubes (#3) or the center section (#1)?  

I would clean the area well and drive around for a while to find the source of the leak.

[Sam Buchanan]

1 hour ago, JonathanC said:

I've also seen mention that there's a breather that could be expelling oil so it may not be a seal at all.

 

 

It's unlikely oil is coming out of the vent but if it is plugged the pressure that can build up in the diff can push oil past the seals. Find the vent (on top surface of the housing on my P15) and make sure the cotter pin in it is free to allowing venting.

 

Many times the leak is at the pinion shaft near the universal joint. The seal can wear a groove in the drive flange which then passes oil....along with the old seal being hardened. Sometimes a Speedi-Sleeve is installed on the flange to allow the new seal to function properly.

 

https://www.skf.com/us/products/industrial-seals/power-transmission-seals/wear-sleeves/skf-speedi-sleeve

 

Here are photos showing how the sleeve works, in this case on the crankshaft pulley.

 

The worn seal surface:

 

 

 

And the renewed surface after the sleeve is installed.

 

 

Edited September 7, 2022 by Sam Buchanan