MX-5000 transmission and hydraulics overheating

jcaron2 · May 31, 2014

A week or so back, my MX-5000 overheated. I had a guy mowing for me, and he noticed smoke starting to come off the transmission housing under the seat. That's when he also realized that the temp gauge was way up, starting to get into the red zone. He shut everything down and let me know. I checked the radiator and found that it was pretty clogged up, especially in the lower half where the battery blocks easy access to clean it out. I took the battery out, vacuumed what I could out of the radiator, then washed it thoroughly with a garden hose until I could get water to go through everywhere.

After that, I fired it up and proceeded to mow, keeping a careful eye on the temp gauge. It stayed nice and cool, even after two hours of running the bushhog. My helper came back to mow again the next day, and the temperature gauge stayed down, but after about an hour, one of the power steering hydraulic hoses blew out, spewing hot oil onto his bare legs. Poor guy! Luckily it wasn't so hot that it actually burned him, but it was clearly hot enough to be painful when it first happened.

I figured that the prior overheating had weakened the hose, so I installed a replacement the next day and called the guy back to try mowing yet again (in the meantime, I ran the tractor around the farm a bit and everything seemed fine). This time, he was able to mow for about five hours with the temp gauge staying fairly cool before ANOTHER power steering hose blew out. This time it didn't get his legs so bad, but it was still pretty hot. Where the oil sprayed on the transmission housing it was actually smoking.

Today I replaced the second power steering hose and went ahead and changed out the transmission/hydraulic oil and filter (along with the engine oil and filter while I was at it). I then started bushhogging again, keeping an eye on the temp gauge and monitoring the transmission temperature by reaching down and touching the housing every few minutes. After about an hour, it was hot enough that it was marginally uncomfortable to have my hand on it. The power steering valve was really hot too. The tractor has always gotten hot when I've mowed (the chassis, not the engine), right from day one, but I'm pretty sure it took longer than an hour to get this hot in the past. Then again, I may just be paranoid.

Anybody have an opinion about what's going on? Does the transmission have a separate thermostat or water pump from the engine? If not, it seems like all that is working fine now. So why would the hydraulic oil still be getting so hot?

Tx Jim · May 31, 2014

Is hyd oil cooler and radiator spiffy clean????? If 3 pt is raising too high it will cause hyd relief valve to by-pass which will heat hyd oil before God can get the news.

Grandad4 · May 31, 2014

If it's an HST machine, it is natural for the hydraulic fluid to get pretty hot under normal operation... as you say, hot to the touch... 185 deg. F is typical. Running the bush hog is one operation that seems to make the tractor work pretty hard so it will definitely heat up pretty well and if it's really heavy grass or the ground speed is too fast, that can run up the hyd fluid temperature even more. It shouldn't be smoking hot, though. We have one place that has extremely thick, tall grass where we just drop the tractor into low range and take our time. Also, you want to be sure the engine is at full PTO rpms under those conditions.

If things got hot enough to fry some of your hydraulic hoses, I'd be concerned the hydraulic fluid itself also got cooked. It would probably be a safe albeit expensive measure to change the fluid and filters.

By the way your MX5000 is a first cousin to my L4610 (which lives in Summerfield, just down the road)... same tranny, FEL, 3 pt, etc. You've got a different engine (gotta love the turbo) and slightly longer wheelbase but otherwise almost the same tractor with many common parts.

nc redneck · May 31, 2014

Not sure what year your tractor is but my Kioti 45 did the same thing last year. It is a 06, 950 hours. After reading many post here I removed radiator fan shield and repeatedly blew out radiator with a water hose and compressed air many times. It was amazing what came out.
This seems to have cured the problem, but I have not mowed in 95 degree + heat yet this year.
Hope this helps
Scott

jcaron2 · Jun 1, 2014

Thanks for the responses, guys.

My tractor is an '05 with a normal geared transmission and about 850 hours. As I said before, it has always run hot, but since this incident I feel like it gets hot much more quickly. Yesterday's mowing session was only about an hour and the grass was pretty short. Normally, I feel like it would take a good two or three hours to have gotten that warm. But then again, I can't say that in the past I've paid much attention to how hot the power steering valve gets. Maybe it's always been like this?

I did change out all the transmission/hydro fluid and filter since the previous stuff probably did get cooked. Luckily it was due anyway.

The radiator is pretty clean now, but I'll give it another round with the hose and the air compressor. It looks clean and water seems to flow through everywhere, but maybe there's still some debris in it.

Anybody know if it's possible to add an aftermarket transmission cooler to this tractor?

Thanks!

Grandad4 · Jun 1, 2014

Sorry for the tangent about HST... bad assumption on my part. On HST machines, there is a hydraulic oil cooler system built-in... don't know if that's true for gear drive MX models, but there's probably no reason why you couldn't add one. I'm not any kind of expert but that seems like a Band-Aid and not a real fix, which would require figuring out whether the excess heat originates from the engine or the hydraulics. If it's the engine that's overheating, the solution is in radiator cleaning and/or other work on the cooling system; if the engine is OK and it's the hydraulics creating the heat, unusual in a gear-drive machine, the heat is a symptom of some kind of internal hydraulic problem that needs to be resolved.

JoeBee · Jun 1, 2014

Page 38 owners manual. Make sure the control screw is in horizontal position with implement DETATCHED -- vertical with FEL. -- Just to the right of your hydr filter. "to prevent overheating and damage to the hydraulic system."

nc redneck · Jun 1, 2014

jcaron2
I did install a A/M fan in front of my radiator about 4 days before removing fan shroud and cleaning radiator with compressed air and water hose.
Never got to use it as radiator deep cleaning solved my problems, that was about 1 1/2 years ago. Its still in there if I need it but so far no problems. FYI my heat issues were very similar to yours heat issue got worse over time, to the point of 2 hours at 85 to 87 of hard mowing would cause problems.
I was doubtful about radiator clean but there is a post on it. Poster made a 6 or 9 inch L shaped copper tube to go on the end of air hose I did the same. Not sure I would have gotten same results without it and removing fan shroud.
I see you are from NC also. I feel very lucky to be born and raised here in NC when I see how things are in other parts of the country.
Good Luck
Scott

jcaron2 · Jun 1, 2014

Thanks, guys! JoeBee, that was a good thought, but it turned out not to be the problem.

I think the real solution is along the lines of what both Grandad and Scott have said (and TX Jim too!). It's got to be a radiator issue. I went ahead and cleaned it really well again today. It looks pristine on the outside. Then I flushed out the coolant. The old stuff was pretty murky looking, and I had to flush with water three or four times before it came out clear (I put in a container of cleaner the first time around). Maybe there was enough gunk and rust inside that it was limiting the heat transfer?

Anyway, I went ahead a bushhogged for a few more hours this afternoon. Things got hot to the touch again fairly quickly, but it never seemed to get any worse. The temperature gauge stayed nice and low. I guess maybe it's working correctly now? I'm still feeling pretty gun-shy. I wish I'd paid more attention before this problem to know exactly how hot the power steering valve and transmission case are supposed to feel. Moreover, I wish this tractor had a hydraulic oil temperature gauge! That would be a lot less qualitative than feeling stuff with my hand.

At any rate, the fact that I can touch everything with my bare hands without actually burning myself (albeit with a bit of discomfort) has got to be a good sign. I would hope things like hydraulic hoses would have to be skin-sizzlingly hot before they'd blow out or get damaged.

I'll mow a few more times this week and let everyone know how it turns out. Hopefully the issue is resolved. Thanks for all the advice!

Josh