Brush Hog gear box leak - Help Please

[DJG]

Hi Guys:

I've got a very old New Idea brush hog which I've been using for of couple of years, without problems. My neighbor gave it to me after it sat in his back yard unused for 20+ years.

Since I want to do some hogging, and after reading a post here last week, I decided to change the oil in the gearbox.

I drained the old oil and put in some new W80 and a funny thing happened.
Half of it just poured right out of the area where the gear box meets the drive shaft. Just a nice steady flow.

This can't be right.
I'm guessing there should be a gasket or seal at that spot.
So either the seal just recently failed (which I doubt), or I've been running this thing with half the oil it needs.

Do I need to take it apart at this point or keep doing what I've been doing? Is ignorance bliss or not?

I sure could use your advice.
Thanks
David

PS - I've got a picture of the oil leaking out but don't know how to get it off my new "smart" phone to this smart site.

 

[Bulldog]

The correct way to fix it would be to take it all apart and fix/replace the seals.

The easy fix would be pump it full of grease and hammer down. A good quality grease will lubricate it just fine. It may not be the perfect fix but it will work. I had a old Bushhog cutter that we ran that way for years. It wasn't used much but it always worked.

 

[DooRules]

Did the exact same thing with a 6' Bushhog mower. Just kept putting in a tube of grease whenever I needed to use it.

 

[GWD]

Yeah, the seal is most likely gone. And you are probably right that the gearbox has been running on low oil for quite some time.

If it were me, I'd take it apart and replace all the seals and gaskets. Seals are fairly easy to find but the gaskets may have to be homemade out of a sheet of gasket material.

But I am inclined to tinker with farm stuff. The grease idea sounds workable as long as it is not so thick as to cause shear pin issues.

 

[DJG]

Thanks for your suggestions, guys.
Yeah, I thought the right thing to do is replace seals & gaskets. For its simplicity, I'm also attracted to the idea of just using grease because I don't use this equipment often. But with that, only be the bottom 1/3 of the gearbox that will hold anything.
To start, I'll go onto the web and see if I can even find the parts and go from there, but the next question is, how tough a job is it to take the gearbox apart and install everything. It looks like just a few bolts, but appearances can be deceiving.
David

 

[bandaidmd]

Take off the top cover and pack it with wheel bearing grease then put a greese fitting in the fill plug hole for routine refills. the gearbox will outlast the chassis.

email yourself the picture from your phone then save it on your computer, after its on your computer its easy to upload thru the go advanced toggle at the bottom of this page.

 

[turck]

The reason the grease is a good idea is you probably have wear to the gears and you might not want to spend to much on a old gear box. check the backlash and end play. How was the vibration when you ran it? Your leak sounds like the input shaft seal. Remove the driveshaft, there might be a snap ring and a clutch or shear pin if there is remove them. then there should be a few bolts on the cover remove them and you can remove the entire cover, input shaft, input gear and bearings. I think you can then slide the cover from the shaft and replace the seal and cover gasket. Its been awhile but thats the way I remember it. The vertical shaft is the output shaft check the output gear, its smaller and moves faster and tends to wear more and may need to have a shim removed from the lower cover.

 

[BadDog]

If the seal is "gone" (as in the rubber part is shot leaving a gap, or actually gone), I would replace it to make sure to keep trash out. But other than that, I would say grease. I replaced bearings and seals in my Ford 905 auger gear box, and I plan to try to run hypoid gear oil at first, to make sure the new bearings receive all the lubrication they need. If it starts leaking, I had thought about switching to 0 or 00 grease, but that turns out to be nearly impossible to find in Phoenix (so far anyway), so the alternative appears to be missing NLGI-2 wheel grease with hypoid 80/90 (or similar) to achieve a heavier consistency. Perhaps like "slime" in a tire, the heavier grease base will help seal up any leak caused by worn shafts, and at least make sure to keep most/more lubrication in the gear box between relatively infrequent uses.

 

[Bulldog]

If it starts leaking, I had thought about switching to 0 or 00 grease, but that turns out to be nearly impossible to find in Phoenix (so far anyway)

BadDog, I'm not pushing a sale just offering info. Amsoil has a 00 Semi-Fluid Synthetic EP Grease. The smallest quanity they offer is a 35lb lug but it can be ordered if you need that type of lubricant.

 

[bandaidmd]

If the seal is "gone" (as in the rubber part is shot leaving a gap, or actually gone), I would replace it to make sure to keep trash out. But other than that, I would say grease. I replaced bearings and seals in my Ford 905 auger gear box, and I plan to try to run hypoid gear oil at first, to make sure the new bearings receive all the lubrication they need. If it starts leaking, I had thought about switching to 0 or 00 grease, but that turns out to be nearly impossible to find in Phoenix (so far anyway), so the alternative appears to be missing NLGI-2 wheel grease with hypoid 80/90 (or similar) to achieve a heavier consistency. Perhaps like "slime" in a tire, the heavier grease base will help seal up any leak caused by worn shafts, and at least make sure to keep most/more lubrication in the gear box between relatively infrequent uses.

amazon has 0,00.000

I got some for my tiller there before I found out where to get it locally.
I ordered 2 quarts and recieved 1 and 3/4 quarts and grease stain on my front porch where ups sat the soggy box. The shipper never bothered to tape the caps on the bottles and one popped off but that stuffs so clingy i only lost a 1/4 of the bottle.
They did credit me for the whole shipment.

 

[BadDog]

Thanks. The problem seems to be getting it in smaller quantities. As far as I could find, it's available in no less than 12 cartridge cases for just over $70. For an old auger, I'm not interested in investing $70 and stocking 11 cartridges indefinitely. If I could get it by the quart, that would be my choice. I read on another board about mixing, and I may just go that route. The new seals should actually seal pretty well, and I just don't see anyway to keep that top bearing lubricated with a heavier grease, so we'll see what happens. My biggest concern is that ambient temp approaches 120here in the summer, and it will be stored out in the sun, so the temp of the unit itself will be well over that. Things tend to thin out, separate, and leak at those temps over the span of months.

 

[DJG]

The reason the grease is a good idea is you probably have wear to the gears and you might not want to spend to much on a old gear box. check the backlash and end play. How was the vibration when you ran it? Your leak sounds like the input shaft seal. Remove the driveshaft, there might be a snap ring and a clutch or shear pin if there is remove them. then there should be a few bolts on the cover remove them and you can remove the entire cover, input shaft, input gear and bearings. I think you can then slide the cover from the shaft and replace the seal and cover gasket. Its been awhile but thats the way I remember it. The vertical shaft is the output shaft check the output gear, its smaller and moves faster and tends to wear more and may need to have a shim removed from the lower cover.

Thanks, turck.
What I discovered talking with the tractor shop here is that there's a top fill plug, a bottom drain plug, and surprise of surprises, there's also a smaller "check" plug...which is a long way of saying the gear box isn't supposed to be filled all the way to the fill plug. Only the bottom half (slightly less) holds the oil or grease.
I ordered a new input seal and may or may not install it after speaking to my farmer neighbors. I'm told I can remove the old seal from the front without taking the gearbox apart, which sounds like a lot easier.
Thanks for your thoughts, and thanks to OTT. This is a great site for novices like me.
David

 

[Stubbyie]

If the shredder has a round stump-jumper-type blade carrier I'll bet you ruin it trying to get it off to get to the gearbox shaft. I've had a couple that will NOT come off even with hydraulic pullers. Resorting to a torch is common and then you burn up and therefore have to replace the bottom seal.

May be easier doing as you've heard here: use a tube or two of standard cheap grease gun grease. We have one running now like this in the hot temps you describe and works fine. I've also dumped in a bottle of thick golden Motor Honey (cheap $1 at WM) with a tube of grease just to make the mix a bit looser to flow better. Those old gearboxes are heck for stout and will probably outlive your interest in using it.

 

[DJG]

If the shredder has a round stump-jumper-type blade carrier I'll bet you ruin it trying to get it off to get to the gearbox shaft. I've had a couple that will NOT come off even with hydraulic pullers. Resorting to a torch is common and then you burn up and therefore have to replace the bottom seal.

May be easier doing as you've heard here: use a tube or two of standard cheap grease gun grease. We have one running now like this in the hot temps you describe and works fine. I've also dumped in a bottle of thick golden Motor Honey (cheap $1 at WM) with a tube of grease just to make the mix a bit looser to flow better. Those old gearboxes are heck for stout and will probably outlive your interest in using it.

Thanks, Stubbyie:
That makes a lot of sense to me. I've run this old beast of a brush hog for hours & hours without incident. The bearings seem fine and everything as tight or smooth as can be. If it ain't broke, don't fix it. So I'll keep the new seal in a box with my other Kubota gear as insurance. Like carrying an umbrella to ward off rain.
Adios
David