Bush Hog Rotary Cutter Loses Lubricant

I have a Bush Hog Rotary Cutter Model 105 Ser#30964. It leaks the gear oil lubricant real fast comin out underneath at shaft at blades. How do I repair/fix? I was told to fill with grease and run it. Is this OK? If I put in grease, how much do I put in? What type/specification grease?

If it is leaking that bad,you might as well take it apart and replace the seal. Filling it with cornhead grease might be a temp. fix. But if you forget to top it off before you use it you risk trashing the gear box. Also if oil is leaking out that fast past the seal, dirt and debris are getting in.

I agree, replace the seal and fill with corn head grease.

Where do I find instructions on taking apart and fixing? Is it a job that requires a large amount of tools? What tools?

Terry it's more of a pain in the butt job than anything. The blade assembly has to come off. The the gear box itself. You will more than likely need a good puller if it had a hub but that can be overcome as most shops have then and will pull it for you now hta you can load the gear box in you car and take it to them. Then you should be able to get to the seal. Just common hand tools.

Rick

Taking the blade hub off the bottom shaft will be the hard part. It most likely has some sort of large nut to hold the hub on. That will be the only large wrench you will need. A good pipe wrench may loosen it after heating if needed. Then a good gear puller to pull the hub. Again heat may be needed.

Heat it then cool it before turning or you may ruin the threads.


Gary

I think they are worth fixing, I hate making a mess inside a gear box by mixing unknown oils, greases which may have incompatible soap bases. It sounds like overkill, most people ignore differentials, think they don't need service, buddy of mine bought a 2nd van for his side jobs, not bad, decent shape 100K miles, but the rear has a noise, took the cover off, you could see the wear, will hold a while, but you will have to listen to the noise, lube in there when cleaned out was like tar, because no one ever changed it, which is a simple thing to do. Thats just me, now if were a slow leak, I'd drop the old oil, replace with a less viscous grade like cornhead grease as mentioned, my old Rhino SE-6 rotary mower actually calls for a similar lube, 0 or 00, one of those 2 which is stringier and tackier (figure of speech) than 80W-90, kind of like Cornhead grease, similar to the old track roller lube used in Alemite volume pumps to lube tracks rollers on crawlers, stays in place, clings better and is more forgiving when tolerances get expanded say around a seal.

This photo shows the out put shaft on the gear box. Its as simple as flipping the mower upside down, pulling a cotter key, taking the stump pan or blade holder off, then there is likely 4 bolts holding the gear box on, on mine, I can easily pull the grade 2 bolt for shear protection on the pto shaft, and with those 4 bolts out, gear box is off, and you can put it on the bench, take to shop. Might be a reach to get to those gear box bolts on either side with hands on each side, 2 people would help. I have not replaced a seal on one of these, but plenty of similar seals, bearings, depends on what it takes to remove/replace, need a press, puller or right tools, don't have, take it to a shop, vs pulling ones hair out LOL ! Once done, refill with the right lube and every year or so depending on use, condensation from cold temps, flip 'er over, drain oil and replace, they last a long time and you know its taken care of, this is usually how they get run dry and ruined, cause people really don't pay a lot of attention to them, just like vehicles, change the motor oil on time but never the differential lube. When removing the pan or blade holder, be cognizant of the fine threads on the shaft, don't deform those or you will be looking for a die or thread file to repair.

As others have already told you, you will need to replace the seal(s) to stop the leak(s). This is not a difficult job for onw who is mechanically inclined and has proper tools. If you are not, you may wish to take it to someone who is.

DO NOT simply fill the gearbox with chassis lube (grease) and continue to use it. That said: ANY lube is better than NO lube.

Dean

Just buy some john deere corn head grease and pump the gearbox full and forget it.That stuff will lubricate as well as oil and not go bad as oil does over the years.

I have what was & old junker that was gave to me 20 years ago because I hate to see equipment like that go to the scrap yard, plus it had new tires, it has gun grease and 90 waight gear lube mixed. I've only had to add lube once or twice in the last 20 years that I can remember and I use it to mow the field behind the house. But like most had said, if it's a good mower it's worth fixing right.

I'm hearing different things.. The mechanic that was working on my 861 about a year ago, said the fix for the bush hog (leaking) was to pack it with grease.

I relied on his 'expertise'..

What do you folks recommend.. Should I have it serviced to remove the grease?

Don't want the one I've got ruined and need to spend the dollars for a new one, if I don't have too..

Its a common practice, that and using a less viscous type oils, like 00 or 0, cornhead grease.
If a slow or similar leak, I like this option myself, buys you time until you can repair it, if so desired, some will not, cause the leak has stopped.

I certainly cannot say what the results are, mixing gear oils, grease etc., lots of people have mentioned no trouble with it here. There is a concern with incompatible soap bases, and although I am aware of this, I do not know what happens in these kind of applications, I do know that large or expensive machinery with lubrication instructions/specifications, mixing soap bases may not be a wise move, again, not the API and or reference standard guru either.

It would be good to hear from someone in the "know" about API, specifications, whats compatible, whats not and what does occur when you do the above.


At a good friends place they have a similar size farm, and a 2020 JD, before their father passed, he traded a sickle bar mower for a small, but seemingly well built 4' wide rotary cutter, and the gear box has a grease zerk, not a plug, wrong blades on it, like someone made them out of old ones, things are not as well taken care of as they should, they've had it awhile too, without issues, but I shake my head every summer when I see it.

I suppose you could clean and flush out the grease, not sure what you would use as a solvent, and or what if anything inside could be affected, other seals, and then replace the seals that were leaking, re-fill with correct lube, might be a wash with whats in there now, or maybe there is a slight detrimental effect over time.

This would be a cool mythbusters project would'nt it, I'd love to suggest it, something interesting to learn, like when someone opens up oil filters and shows what they look like.


You could also check for metal particulates, flakes and so on in the existing lube, that would definitely tell you something is wearing.

I would not worry too much about it, I'm a bit "...." retentive myself, but like most others sometimes let it go, I do like following MFR instructions and or specifications when ever possible just the same.

SHARP '64 convertible!!!

Thank You..

The tractors themselves I definitely follow the specs. The bush hog seemed logical with grease..

The mechanic said he does it for everyone, he knows..

The bush hog has been lightly used this year, the horses et. al. eat it so outside of esthetics
making the farm look nice.. I kind of let it go..

Price of bush hogs now a days it pays to make sure..

Thanks again for your response..

Marc

(quoted from post at 10:45:05 09/09/12) Thank You..

The tractors themselves I definitely follow the specs. The bush hog seemed logical with grease..

The mechanic said he does it for everyone, he knows..

The bush hog has been lightly used this year, the horses et. al. eat it so outside of esthetics
making the farm look nice.. I kind of let it go..

Price of bush hogs now a days it pays to make sure..

Thanks again for your response..

Marc

Click to expand...

Marc, I've worked as a mechanic. I would never, ever tell someone to do something like that from a liability stand point. After following this guys advice he would be liabile for any gearbox failure. The gear box lub works on the splash principal. At some point in time that grease if going to dry out and you are going to loose a bearing or eat the gears up. It's a little labor and a seal. Fix it right.

Rick

Thanks Gene, my wife sister bought it new and she gave it to me in the 70's. Actually I bought it from her but she sent me my money back. Always been inside until about a year ago.

DO NOT use chassis lube in your gearbox (unless the alternative is no lube of any kind).

The gears are case hardened. 90W CL5 or equivalent has EP additives to protect the thin hardened surfaces. Chassis lube does not have such additives.

If you have minor leaks CNH Pourable HIGH EP Grease is the recommended alternative but it will not stay in gearboxes with badly worn/damaged seals.

Again, ANY lube (even chassis lube) is better than NO lube.

Dean

Sorry: CL5 should be GL5.

Dean

The myth is busted. DO NOT use chassis lube in a rotary cutter gearbox if you plan to keep the cutter. See above.

This IS a common practice by tractor/implement jockeys when selling cutters with leaking seals.

Those who doubt: Stop by, and I'll show you the results.

Dean

I see 390/427 badges.

Dean

I see 390/427 badges.

Dean

You may have picked up something under the pan that wrapped around and tore out the seal. If you put in grease, it will heat up and leak out. Just fix it. The seal is pretty cheap and you will spend more on labor that the cost of the seal.

know of one here that was used with grease for over 30 years, don't know about it now brother has it...another thing the third link was a chain as all of the three point hitch bush hogs are that we use...