Water somehow getting into Bush hog Gearbox

aaluck · Apr 1, 2020

I purchased a used Bushhog 286. When I got it the first thing I did was empty the gearbox. (The photo shows the first drain of my finish mower I got with it, but the same as the 286). What came out was a cream colored oil--obviously water had gotten in. Because there is no drain hole I sucked out everything I could.

I filled it back up to the check hole. Just enough so that it seeped out a tiny bit and put the check plug back in. Wrapped plumbers tape round the threads of the check hole and fill hole. Used it twice, over two weekends and after I was done the second weekend I decided to check the oil to see if any needed to be added.

When I opened the check hole cream colored oil came POURING out--so obviously the fluid level had increased a great deal over the two weeks. The bottom seal shows no sign of leaking. The PTO seal shows no sign of leaking. The gasket around the top of the gear box looks in great condition--still has original paint on it.

Any ideas on what could be going on......?

Dave_eng · Apr 1, 2020

Read some of the posts on the following forum and I think you will realize it is not only water that can produce foam.

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2111537

When you next remove the oil, place it in a glass container and let it sit for a week. Any water will migrate to the bottom of the glass container.

I doubt any is getting in.

Dave

BigG · Apr 1, 2020

Are you storing it out side? Hooked to the tractor?

My hog hangs out of the cover so I cut a plastic bucket to fit over the gear box and set the tail wheel up on a block so the rain water can not run down the PTO shaft to the seal just in case.

Also there is not much oil in the gear box so the new oil may be contaminated by the water from the first time?

And I am with Dave the oil may be change colors as it entraps the air but does it expand enough to pour out of the gear box as shown?

Maybe draw some of the oil out of the gearbox and watch it in a glass to see if it separates.

aaluck · Apr 1, 2020

Dave_eng said:
Read some of the posts on the following forum and I think you will realize it is not only water that can produce foam.

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2111537

When you next remove the oil, place it in a glass container and let it sit for a week. Any water will migrate to the bottom of the glass container.

I doubt any is getting in.

Dave

Thank you both for the replies. Very informative and explains (maybe) the color. But my question is the same as BigG...Why is the oil level rising to the point of it pouring out of the check hole, when it is only filled to the bottom of the check hole?

NHSleddog · Apr 1, 2020

aaluck said:
Thank you both for the replies. Very informative and explains (maybe) the color. But my question is the same as BigG...Why is the oil level rising to the point of it pouring out of the check hole, when it is only filled to the bottom of the check hole?

Micro bubbles of air will increase the volume and can affect the color if you get enough of it.

freewheel3 · Apr 1, 2020

NHSleddog said:
Micro bubbles of air will increase the volume and can affect the color if you get enough of it.

Plus, if it was cold oil put in a cold gear box, the level will increase once the oil and gear box warm up. Not sure if it would account for that large of an increase, but it will account for some of it.

SDT · Apr 1, 2020

aaluck said:
I purchased a used Bushhog 286. When I got it the first thing I did was empty the gearbox. (The photo shows the first drain of my finish mower I got with it, but the same as the 286). What came out was a cream colored oil--obviously water had gotten in. Because there is no drain hole I sucked out everything I could.

I filled it back up to the check hole. Just enough so that it seeped out a tiny bit and put the check plug back in. Wrapped plumbers tape round the threads of the check hole and fill hole. Used it twice, over two weekends and after I was done the second weekend I decided to check the oil to see if any needed to be added.

When I opened the check hole cream colored oil came POURING out--so obviously the fluid level had increased a great deal over the two weeks. The bottom seal shows no sign of leaking. The PTO seal shows no sign of leaking. The gasket around the top of the gear box looks in great condition--still has original paint on it.

Any ideas on what could be going on......?

Condensation due to thermal cycling.

This is the primary reason why it is recommended to change the oil every two years or so.

Because of the lack of a drain plug in the lowest part of such gearboxes, much/most of the water remained in the bottom after you removed what oil you could.

I sometimes add a bit of "Dri Gas" to gearboxes, transmissions, etc., a couple of weeks prior to changing to absorb as much water as possible prior to changing oil.

SDT

Bulldog · Apr 1, 2020

It's almost impossible to get all the old oil out of those gearboxes. May have to change it several times before you get it clean.

Also need to make sure the vent is open so it can breath while it's being used.

aaluck · Apr 1, 2020

Thank you all very much. I feel much better about it now. Ill use all of the suggestions and check it before and after (it has cooled down) and see.

Thanks again

Pau7220 · Apr 1, 2020

aaluck said:
Because there is no drain hole I sucked out everything I could.

Any ideas on what could be going on......?

Don't forget the water will be on the bottom. That's why "sucking out" doesn't work.
I lift mine up with the loader and a chain so the drain plug is down. I'd stay away from any alcohol based drygas as it WILL damage seals. If you need to flush use mineral spirits or kerosene... at least they're petroleum based. What lube does that unit call for? If regular gear lube, upgrade to full synthetic. When you get it full and clean, I'd leave it standing on end to really see if that top gasket is doing its job.

NHSleddog · Apr 2, 2020

I have an old one that I flip up and over to drain. Used to use chains now I use forks. Full drain every time.

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Water somehow getting into Bush hog Gearbox

aaluck

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