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Discussion Starter · #1 ·
Everything was going great until I didn't have a way to suction the old gear box oil out of my new (OLD) 513 brush mower. But, when I peered into the bottom it was empty and rusty, so no worries. I got it filled NP, and it works real good for a rusty Italian gear box, no issues were heard over the whine of the 855 hydro pump (IS that whine normal?).

So 2 questions:
1, Is that whine normal, and 2, what treatment product is best to maybe burn off some of the rust inside the gear box, for the reason I suppose all that loose metal will be a constant source of fines in the oil/gears.

My hunch is there is nothing to do and the gears are tough and will last forever, but if there is something productive to do, I am all about it. The machine was well-greased historically, judging by the good amount of fresh, slightly old and real old grease, and tightness of PTO and wheel bushings. The gear box did not drip after I filled it, at least not within the hour is was up on jack stands.
 

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Most hydraulic systems have a whine to them, some louder than others. If oil level is good and the proper, fresh oil is used, I wouldn't get concerned.

I WOULD get concerned about the gear box though! Being that it's used, empty, and rusted, I'd say it has been run for xx hrs./time without lube. Worst case scenario here is that the bearings are worn enough... from being run dry... to have an adverse affect of the gear teeth alignment/mesh, resulting in gear failure. By adding oil to the gear case, it is now possible for some of the rust to break free... due to expansion/contraction from operating. These rust particles can find their way into the bearings and can lodge between the balls and the races. They can now act as a "brake" on the balls and they will "skid" around the inner, outer races, or both races may spin, destroying the case/shaft/ or both! Best case scenario is nothing will happen and you'll be fine!

If this were mine, I'd dismantle seals, bearings, and gears. I would find replacement seals and bearings... either through a parts list, numbers on the parts, or by measuring... and sandblast the empty gear case. There may be other means of removing the rust through chemicals or you could use a rust converter, like Rustoleum Extend, but I'd sandblast. Mask/tape seal & bearing bores and request sandblaster to stay away from these areas. Upon getting gear case back, I'd blow with air and wash with solvent, probably 3 times! Then put some oil in it, roll it around to coat all surfaces, or spray LIBERALLY with WD-40. New bearings & seals can be installed and you'll be...worry free... good to go for 30+ years.

Just my personal thoughts and the way I do things! Bob
 

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At a bare minimum, I would run it a few hours, vacuum out the oil, and look at the gears. If everything looks okay, refill with clean oil. If not do as suggested by Bob.
 

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IMHO if 513 gearbox is operating quietly I would not do anything to it but check oil level before mowing, If oil level dropped I'd add JD Corn Head lube(NLGI grade O) or it's equivalent & continue mowing. My JD 709 rotary mower with a faulty lower seal has been mowing fine with Corn head lube for yrs.

 

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I have heard/read that Cornhead Grease is a suitable replacement for gear oil in gearboxes. The type of lube used is not my issue, but rather possible contamination of that lube due to debris... rust... in the gearbox. As gears and shafts rotate, the lubricant is put into motion. Bearings too will provide a small amount of motion to the lube. As a bearing approaches a load zone, lube is pushed out. as the bearing enters the unloaded zone, lube is drawn back in! This motion or circulation of the lube may have a tendency to "wash" the rust particles from the gear case walls. I'd think the backlash in the gears is greater than the rust particle size, so no worry there. I also believe the rust particle size is larger than the bearing clearance and can lock a bearing and prevent it from rotating. Bob
 

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Run it for a little while and change it again. Repeat until your oil stays clean. You may want to fill it with diesel and run it with no load for a few minutes on the first flush and fill.
I use a pump like what is in a bottle of hand soap with the long tube that goes into the container. Stick that down in the gear box and then pump it out into a container.
If it leaks, convert to cornhead grease.
When buying used PTO equipment always check the gearboxes for oil.
 

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Discussion Starter · #7 ·
Righto. Appreciate the solid scenarios, will check it and go from there. Would enjoy doing a complete rebuild and powder coat... but if it is fine, that would be nice to work in when it fits. I did a 100% full service of the hydro/tractor, so I'll figure that whine is the factory whine.
Happy trails and keep the dirty side down, and in the dirt.
 

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My only worries would be the seal(s) since it was dry, and the bearings. I think the gears, being hardened, will survive the rust particles that end up in the lube.
 

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Hmm, I forgot about seals! Yes, rust particles can also damage seals or get imbedded in seals and damage shaft sealing surface! Thanks Zebrafive! Bob
 

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Discussion Starter · #10 ·
All the comments were helpful in gaining an idea of the range of what options I had for next steps, and gave me a good game plan. Thank you!

I did run some spec gear oil and then in lieu of cleaning it with diesel, I almost filled it with Evaporust to let it sit last night (that stuff is fantastic and often gets stuff down to bare metal or if it was pitted, at least cleans the rust real well), but decided against it due to its poor lubricating qualities, and the difficulty of extracting it all from in between the bearings. It would have been fine as the O grease worked in, but decided to let sleeping dogs lie and not mess with the light surface rust inside the box as it seems well adhered and stable.

One correction: The gear box that is rusty on its inside surfaces is Chinese (not Italian like I thought it was due to the PTO slip drive cover) gear box. The gears themselves were 99.5% clean, only a smidge of rust starting on one shaft.
So, I ran gear oil for an hour (3 weeks back) and after that added Blue Devil hydro seal refresher and it didn't leak a drip over the past 3 weeks. I ran it 5 minutes while adjusting the slip clutch and then pulled the cover and suctioned out all liquid and blew it out of the bearings for 20 minutes, which pushed out a few more OUNCES of liquid that I sopped up. Not sure where all that new oil was blowing out of, the shaft must go down below the gear box a bit. No rust /metal particles noted at bottom and no scale flaking under light friction.

Gear oil looked like chocolate milk. JD corn head grease tube states it is for gear boxes with leaky seals, and also that it has some (minimal) anti-rust properties, and as a bonus, the grease color matches the JD Green paint. So, now the inside of my gear box looks better than the outside. That stuff is fantastic. Grade O flows reasonably well, but I made an injector and shot it into the bearings and then filled the box about half full, about 1/4" higher than the oil level setting. Going to sand blast it and paint it up, now that I know it will last a while. The gear teeth did have a tiny bit of play/delay when you first turn the PTO shaft by hand, until the lower gear rotates, maybe 3/16" movement at the top of the gear at the top of the gear box. Top gear looked square and new, lower one more pointy teeth but not sure if that's worn or not.
 
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