2555CL HST sizzling hot transmission. Causes?

erkme73 · Jun 5, 2019

I drove my tractor about 2 miles, WOT in H with backhoe attached. Route is slightly hilly, and it seemed to slow more than normal. By the end of the trip I smelled burning plastic/paint. Upon further inspection, I found the tranny on the left was hot enough to sizzle spit. The paint is gone, and metal is rusted there (so it's been doing this for a while apparently). People have mentioned dragging brakes, but I don't know how to verify other than looking at linkages from the pedal on to the the undercarriage.

Any suggestions would be appreciated.

CincyFlyer · Jun 5, 2019

That doesn't actually look like burned paint to me, but what can you really tell from a picture? You should be able to coast down a slight grade to see if you get pull to one side from a dragging brake. And check the HST fluid level.

rdinatal · Jun 5, 2019

Looks like a lot of mud/hay. Not sure if yours has a transmission cooling fan on the input shaft. Best to check that for damaged or plugged blades.

mikeman1 · Jun 9, 2019

I would clean off the mud/grass too, it will hold the heat in.

boomer1025 · Jun 9, 2019

mikeman1 said:
I would clean off the mud/grass too, it will hold the heat in.

:thumbsup:

TnAndy · Jun 9, 2019

Not sure how your backhoe mounts, but check this:

I had a Bush hog brand backhoe on my previous tractor (sold them as a package, glad to see BOTH of them go...tractor backhoes are a waste of time IMHO....your mileage may vary), it was a 3pt hitch mount unit with a PTO pump. When the unit was first mounted, it had a slide type top link that you positioned the unit, then welded the slide permanently (per install instructions, not something I made up). But what I found one time was when I put the unit on the tractor, I pulled ALL THE WAY UP on the handle for the rear lift. This was forcing the hydraulic system to try to lift an immovable object. I didn't even notice it for a while, other than the tractor (HST) seemed to have lower power than normal.....BECAUSE IT WAS TRYING IT'S BEST TO LIFT !.

I finally realized what the heck was going on, threw the handle down below the point it was trying it's best to lift, and noticed that slight noise I'd heard was the pressure relief valve for the rear lift has stopped bypassing fluid. It was also causing the hydraulic fluid to heat way up with that strain, and continuous bypass going on.

SO, if your's mounts that way, check out your rear lift to make sure you ain't as stupid as I am.

Diggin It · Jun 9, 2019

The mud, grass, rocks and all need to be cleaned away. The point of the red arrow doesn't look overheated, but it does look like it's worn to bare metal/rust which may or may not be a factor or indicator. Get one of those handheld infrared thermometers for $20 or so and take a few readings in that area during operation. Probably shouldn't ever go over 200 degrees.