Gearbox fluids

1361 Views 6 Replies 3 Participants Last post by DaveDelux, Dec 24, 2021

DaveDelux

Discussion Starter · Sep 9, 2021

I picked up my 1025R a few months back and have been diligent about checking the fluids; I check them before almost every use. It's quick and easy to give a look at the hydraulic fluid, engine oil, front axle and coolant. The one thing I never got to is the gearbox of the MMM. I finally went to check and change the fluid yesterday and found just a small amount of chocolate milk in there. I had figured that it was a "sealed" unit, so it should have been ok.
Everything looked ok in there, but I'm disappointed that I was running it without lubricant. After all that, it wasn't even a big deal to check.
I'll keep a better eye on my gear boxes from now on.

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rwmeyer

· #2 · Sep 9, 2021

Dave, I'm not familiar enough with your MMM to know if it should have a vent plug, but if it doesn't add/make one!

Here's what's happening with a non-vented gearbox:
As you operate the MMM, the gearbox warms up, the lube expands and gets forced out past the seal(s). When finished operating, gearbox cools, lube contracts, and air is sucked in past your seal(s). Living in Florida, I've gotta think you have humid air. When this is sucked into gearbox and everything cools down, condensation is formed inside the gearbox. This gets churned up the next time you operate and... chocolate milk!

If you add a vented plug, you'll still expel & suck in air and condensation, but you'll still have lube! Check lube level about 40-50 hours and stick a screwdriver into the oil and examine color. When it gets too milking, suck lube out (I don't think the gearbox has a drain!), and refill. Bob

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RalphVa

· #3 · Sep 9, 2021

Can't comment on your sealed gearbox. Sounds as though rwmeyer has it pegged.

I very rarely check the gear boxes and hydraulic oil. Just look for any leaks left on concrete floor. Same for vehicles. No oil spots and generally no problems. Had not heard about a completely sealed unit. They'll all generally have a vent.

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DaveDelux

Discussion Starter · #4 · Sep 9, 2021

rwmeyer said:
Dave, I'm not familiar enough with your MMM to know if it should have a vent plug, but if it doesn't add/make one!

Here's what's happening with a non-vented gearbox:
As you operate the MMM, the gearbox warms up, the lube expands and gets forced out past the seal(s). When finished operating, gearbox cools, lube contracts, and air is sucked in past your seal(s). Living in Florida, I've gotta think you have humid air. When this is sucked into gearbox and everything cools down, condensation is formed inside the gearbox. This gets churned up the next time you operate and... chocolate milk!

If you add a vented plug, you'll still expel & suck in air and condensation, but you'll still have lube! Check lube level about 40-50 hours and stick a screwdriver into the oil and examine color. When it gets too milking, suck lube out (I don't think the gearbox has a drain!), and refill. Bob

That sounds like great advice. I do have a vent, but I'll get better at checking the level and condition.
Thanks.

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DaveDelux

Discussion Starter · #5 · Dec 23, 2021

I think I found the cause of my milky colored gearbox oil. I didn't realize that the vent was supposed to have a cap on it, because I have never seen one before. I ordered a new one for $2, and now my gearbox oil stays looking like oil.

In this picture, the old vent is still attached, and the new vent is off to the left.

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Also, fluid doesn't leak out any longer when I stand the deck vertically.

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rwmeyer

· #6 · Dec 24, 2021

Good find Dave! Keep an eye in your seals though when you check oil level. 10 years +/- down the road you may find your seals leaking. But do to filter material in your vent being clogged. This will now act as a non-vented vent plug! Change vent and see if seals still leak.

My thinking is that under that cap is some type of filter material that can become clogged over years of use. Maybe it's just a sheet metal cap or it does have a filter inside, I really don't know! Just suggesting possibilities! Bob

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DaveDelux

Discussion Starter · #7 · Dec 24, 2021

rwmeyer said:
Good find Dave! Keep an eye in your seals though when you check oil level. 10 years +/- down the road you may find your seals leaking. But do to filter material in your vent being clogged. This will now act as a non-vented vent plug! Change vent and see if seals still leak.

My thinking is that under that cap is some type of filter material that can become clogged over years of use. Maybe it's just a sheet metal cap or it does have a filter inside, I really don't know! Just suggesting possibilities! Bob

Thanks Bob...good advice!

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