Leaking deck gearbox, GR20/12 series

[GeneralEclectic]

I have a GR2120 with the 54" deck. The deck's gearbox is coated in oil. Looks like it leaked from Day One, four years ago. I saw it a while ago, but thought the oil around the gearbox was nothing more than some leakage from a breather, but after I look at it in detail, I see there's no breather. (It would be nice to have one, actually) So, when it heats up it pushes out the gear oil from the seal behind the u-joint. My question is how difficult a job is replacing this. I've changed seals before in small and large engines, but I'm unfamiliar with this particular piece of equipment. From the IPLs below, it looks like it could be pretty easy. Pull off the u-joint (not sure how that's held on, hard to tell from the shaft pic, but may be just the clamp), drive out the old seal and drive in the new one. However, the "Nothing is ever simple" rule may be operative here and, in the edge case, breaking down the entire box could be necessary. I'm hoping someone is familiar and can give me a push in the right direction. I *really* don't want to pay my dealer $400 for a $20 seal replacement.

 

[arto98607]

Maybe you should get a workshop manual for that deck.

It may need more than oil seal if it's been leaking oil for 4 years?

IE. It may have ran with too low oil level.

 

[Richard001]

Looking at the parts list, I don't see a plug or a place to add or check the oil level in the gear box.

Is there one ?

Richard

 

[GeneralEclectic]

On the discharge side of the gearbox there are two plugs, one (larger) higher than the other. It looks like the lower is the drain and the upper one the fill. I assume it's like other transmissions, differentials, and misc gearboxes: you add to the upper until it flows out. I don't see or hear anything wrong with it otherwise. There was some oil in it when I drained it a few days ago.

 

[Richard001]

Your thinking that the heating up of the gear box during use may have some truth, but it would be only the air that would expand when heated, and I don't know the physical size of this gear box, but I suspect that when the oil level is up to the correct height, there is little air trapped inside.

But it would be easy to drill and tap a hole in the top of the gear case and put an breather of some sort on it.

Richard

 

[GeneralEclectic]

But it would be easy to drill and tap a hole in the top of the gear case and put an breather of some sort on it.

Richard

Wellllll..... Dunno about that. I thought of it, but without disassembling the box entirely, how would you clean out the chips caused by drilling the hole? Wouldn't want loose metal floating around in there, for sure. OTOH, if I do end up taking it apart, I will install a breather. I already have some appropriate filters for it.

 

[arto98607]

I would certainly open up the gearbox to inspect it.

Here is a photo of JD5801 one-way vent I installed on my aftermarket gearbox couple of years ago - no need for screen.
I did open-up in order to drill & tap it.

This 90* gearbox & 72" RD deck are obviously different than what you have, but that should not be a big deal.

 

[Richard001]

As [SIZE=4][B]arto98607[/B][/SIZE] said, opening up the gear box might be a good idea. However, you can drill a hole in it without getting chips inside. Put some heavy grease on the drill bit. The chips will stick to the grease. Occasionally clean of the grease and chips, reapply grease and kept at it.

Richard