Leak in left rear

1941 Farmall A.
Leak in left rear. I thought it was from the pan with the 10 machine screws, but I fixed that leak. It's from the "hub" or whatever. How do I go about looking for it? After removing the wheel, how do you suggest I proceed. I can see leakage that has dripped down to the housing with the four machine screws on the inside of the hub area. Seems to be oil coming out of the hole above that. It has to be either a seal or a gasket. I can always make my own gasket, but I HAVE NEVER SEEN ANY SEALS FOR SALE IN ANY OF THE FARMALL CATALOGS OR ONLINE SERVICES. What have some of you encountered with these leaks and how to fix? It's leaking on my newly sandblasted rims and newly painted rim and I DOESN'T LIKES IT!!! Tom

Just to make sure I'm oriented right (that's a challenge each and every day!), you are finding oil that has dripped down onto rectangular cover on the inside of the final drive, the one that covers the inside end of the axle. If that's the case, and you recently fixed the leak on the pan and refilled the final drive, and then the leak appeared, that suggests pretty strongly that you need a new seal where the differential shaft passes into the top of the final drive. If this were happening on the right I could pretty wwell guarantee it. Where it's on the left, however, and the fnial is bolted hard up against the tranny, it could also be the seal where the other end of the diff'l shaft passes into the transmission case. Have you done any work on/added any oil to the tranny lately.

If I'm understanding the problem correctly and you already have the tire, rim and wheel off, you're halfway to finding and fixing it. You'll need to pull the final drive off and have a look-see. Part of me says don't disturb anything that isn't leaking -- the other part says replace all the bearings and seals you can get to while you have it apart.

Scotty, thanks so much for your differential diagnosis. I have never been into the rear of either my 1952 8N or the A. So, I am in the learning process here. No, I don't have the wheel pulled yet, but I'm lucky that it is the LEFT wheel because, as you well know, I'm not dealing with an 165 pound casting on that side!!! After I stop the tractor from my almost daily rides, I see the oil that has dripped onto the rim, of course at the bottom of the rim. As you know, like water leaks in an attic, you have to investigate the source, not where it has leaked down to. I have NOT added any oil lately other than refilling the 3 pints in the left pan, after I had it apart for sandblasting and painting. I have not added any oil to the tranny for 4 months. If you can give me more of a blow-by-blow on the take down, once the wheel is off, I'd appreciate. I'm with you on going ahead and replacing more that just the leak for preventive maintenance. Thanks, Tom

I have replaced a few of those seals... There is a seal at the carrier in the rearend and also a seal in the drop housing... Brake band sits in between...

Seals available from your IH dealer...

Okay. If the leak is on the outside and you see no oil near the rectangular cover for the butt-end of the differential shaft, then it is likely from the seal on the axle. That's pretty straightforward and can be done with the final drive still mounted to the tractor - remove the pan and the bearing cover on inside end of axle, remove bolt, and then axle (making careful note of the order and direction of the gear, spacer, washers and other parts) and have a helper let the bull gear down so that nothing gets dinged or broken (gears OR toes). Replace the seal which is inside the bearing retainer on the outside end of things, reassemble, replace oil. Go.

If, as I think we are actually talking about, the leak is manifesting on the inside of the final drive, then it is one of the two seals on the diff'l shaft. That will require removing the final drive. Not too bad a job. Can actually be done by hand if you take the pan, bull gear and axle out like I described above. What's left after that, especially on the left side, is more ungainly than it is heavy. Remember before trying to pull it away to disconnect the rod on the brake band at the clevis where it connects to the pedal. Two folks of average strength can then handle it easily. And having removed the pan, gear . . . gives you a dandy flat spot on the bottom to set it on. Remove the brake band from the drum (keep track of the anchor dowel) and the drum from the shaft and start looking around. To get to the seal on the final drive, you need to remove the rectangular bearing cover at the outside end of the shaft. A healthy bump on the inside end of the shaft will start it loose. (There is a snap ring on the outer end, but I'm pretty sure that all it does is hold the bearing in place on the shaft -- I don't THINK you have to remove it to bump the shaft out) The seal will be looking right at you on the inside face.

As far as the transmission end, the seal will again be looking right at you already. The seal can be removed and a new one installed without removing another thing. If your bearings are quiet, I wouldn't mess with removing the bearing retainer to change that particular bearing. If you think it needs changing out, just be mindful of the shims that are sandwiched between the retainer and the transmission case, and see that they are clean and back in place when you reassemble.

That's sort of about it as far as the wrenchin' part. A last thought about seals. There are two issues that may come up. One, I can guarantee, is that the new seals will not have as deep a shell on them. Some folks will recommend replacing the existing with two new seals with a abundant packing of grease between the two. Others say that a single new seal will work fine. Your decision there.

The other possibility is that the section of the shaft shere the seal rides may have been worn down to the point that a new seal won't be effective, at which point you get into the neeed for a speedi-sleeve. That's a whole other issue, but it may be needed, so that's a heads up.

Scotty...thanks for your reply and for all of your detail. Tom

Rootsy...thank you! Tom

You're welcome!