Leak final drive

Just what did you over grease? Only lubrication practice that has anything to do with final drives leaking is how full you fill them and with what. Would be hard to over fill them since the excess lube will run out the fill port as fast as it is put in. I'm confused.

Sprocket/final drive seals usually leak because they are damaged or the final drive bearings are loose.

First step would be to jack up that side of the rear of the dozer to get the weight off the sprocket where the leak is showing up and then take a long pry bar and try to move the sprocket side to side, up and down etc. Any movement is too much, but I am going to say that if it won't move, adjusting the bearings is unlikely to stop the leak. If it moves when you pry on it, adjusting the bearings MAY stop the leak........or slow it down.............. or not.

The next question is whether the leak is on the outside of the sprocket or the inside. Outside seal can be changed without nearly the difficulty of the inboard one because pulling the sprocket is required to access the inboard one.

More information please.

CCjersey thank you for sharing. The pic does not show location well but the leak is outside of the sprocket.
I've copied and pasted the below string from a final drive leak issue from the archives of a few years back that OM was commenting on. There are other posts as well which support that over greasing can cause the final drive sprocket seals to leak. The zerk I'm referring to overgreasing is the rear sprocket main outside (one each side). Over greasing these can cause the outer seal to push away and allow to leak. Thank you again..


07-18-2008, 08:56 PM #3




Old Magnet



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Nice D7
That's not a serious leak....and yes over pressure greasing may have caused the seal to push out. The outer track frame bearing would have to come off for access.
I'd live with it until more serious undercarriage work is required.

Seems to be some confusion here. There are actually two seals outboard of the sprocket. The one that gets grease is the outer bearing that the track truck pivots on. Has nothing to do with the outer sprocket bellows seal.

If this is coming from the outer track frame bearing, take off the outer cover and make sure that the big nut on the sprocket shaft is good and tight and that there is no play in the sprocket bearings as OM described, if all good, put the cover back on and just keep greasing. The oil from the final drive itself can only get past the outer hub if it is loose on the sprocket shaft. you are working on a hillside and oil is coming along the hub keyway, or the shaft has turned at some time putting the keyway in the wrong place. If the final drive is good and clean and the bearing hub tight, all is OK.

I am hoping this pic will clarify to you with the knowledge and experience exactly what I am talking about. The shinier spot on the tread linkage is w here the drip is,,where the cup caught the oil over the space of a week. This is also exactly where I pointed camera upward from showing drip. A little higher up and outside is the outer zerk that I shot the grease to. My dad as I recall taught me when using grease gun to apply usually a few shots until visible new grease is observed being forced out of whatever is getting the grease. Most all greasers know the sound even of slight popping while air and old grease is forced out of a bearing getting new grease. I never heard or visibly was able to see any excess grease though that was my desire....to be sure plenty of grease is where needs be. Thanks all again.

That looks pretty typical of a leaking outer bellows seal.

On closer inspection of the first pic, it looks to me as if the leak is between the bearing adjuster nut and the hub, there is a cork seal in there, if it was the bellows seal, the oil would be coming from the other side of the nut and be spread over the seal dirt guard and on to the sprocket.
Try adjusting the bearing pre-load up a bit and run on to see how it goes.

The 6B4941 gasket is what catsilver is referring to.

I have manual showing very similar diagram as yours OM. The 6B4941 gasket CS is talking about looks to be away from sprocket nut. Does this seem to be repair where OK to not lift since sprocket is left alone? Estimated time involved? Also will CAT have gasket? Thanks CS OM.