Gearbox grease instead of oil

sandman2234 · Aug 16, 2009

My old flail mower (JD25a) gearbox seal has seen better days. During my last mow, it spilled the oil from the gearbox all over the front of the mower. I realize that this could mean I have a bearing going out, but didn't notice any strange noises, so hopefully it is just from a dried or cracked seal. Remembering that a bush hog can be run with grease in the gearbox when the lower seal goes out, I thought I might ask if anyone had any experience with adding grease to the gearbox instead of replacing the seal on a flail mower. I will probably replace the seal this winter, but right now the grass is growing faster than ever.
Any reason not to do this?
David from jax

MikesTractor · Aug 16, 2009

I haven't used grease in a flail mower gearbox, but like you, I have used it in a rotary cutter gearbox. The only thing I see is that with a rotary cutter gearbox, as it warms up, the grease would tend to seep down to the lower bearings. I'm not sure how it would do on the front bearing of the flail mower. But then again, on the rotary cutter box, there is no oil to it either, and I have seen them run for years filled with grease.

If you filled it until it started coming out the front seal, do you think this would be too much?

I would say try it. If it works, it will give you a little time, if it doesn't, you're going to have to tear it down anyway.

Mike

sandman2234 · Aug 16, 2009

Well, I tried it, and it didn't work. Originally the front seal started leaking, but after putting grease in it, the grease (mixed with residual oil) started coming out the side seal, which is pretty perplexing. I did get the front yard mowed, and managed to get the tractor stuck in my neighbors front ditch (it is a little wet around here due to all the rain we have been having). Another neighbor came up and pulled me out, but their ditch is a mess. It will have to wait until it dries out around here before I can fix it.
While it did work long enough for me to mow my yard, I am not going to continue to use it until I replace both seals.
David from jax

MikesTractor · Aug 16, 2009

Well, I was hoping that the grease would work for you. Kind of strange coming out of a different seal.

At least you tried. As I have always heard, Nothing ventured, nothing gained.

Mike

art · Aug 17, 2009

I might try the grease in a slow moving low load gear box but not on a mower deck!

bjr · Aug 17, 2009

I've not tried it yet either, but I remember the guys here talking about using cornhead grease. I'm not sure what that is or if it's different from say EP 2 grease that I use on universal joints and front spindles on the tractor. bjr

Soundguy · Aug 17, 2009

art said:
I might try the grease in a slow moving low load gear box but not on a mower deck!

Depends on the gearbox too.... I have a mower that actually specs a nlgi 00# grease.. or 85-140 oil.

still.. for the op.. the seal repalcement is the way to go.

soundguy

kenstrac · Aug 17, 2009

If it leaked before and you replenished with grease and it leaked from somewhere else could your vent be plugged?

sandman2234 · Aug 17, 2009

Might look into it, to make sure the vent isn't clogged.
I got to thinking that the residual oil might be the reason the grease was so quick to come out. With a Rotary mower, when the seal goes out, all of the oil drains out the bottom almost immediately. With this flail, the seals aren't at the bottom, so all of the oil doesn't drain out. I didn't drain it out, so it became a sloshy mess, instead of the way you would see in a rotary mower. (I had one that came with grease, from a previous owner). I think this might work if you took the time to remove the latent oil, but if you do that, why not just put seals in it? If I took the time to crack the gearbox open, then it would just get new seals. End of problem.
David from jax