Too much work for a compact tractor?

TNGP · Jul 5, 2016

While I'd love a M108S with a FEL, or even a M7060 - right now I've got a nice little B7500. I use it to pull out large logs and concrete debris from the hollar on my property. I use it to mow with a 3pt. and other "heavy" pulling needs (moving trailers around etc.). It does all of these things very well and runs out of traction before power 99.5% of the time.

But, here's the issue. When working hard and in hot weather (90F+) in low gear, my HST transmission gets incredibly hot. Though I don't have a temp gun yet, it's safe to assume that its about the same temp as the "in" side of the radiator. It's hot enough to make me wonder if I need to install a large after market (flex-a-lite) oil cooler. I know this sounds like an amateur post and a quick answer is "things get hot when worked", it still leaves me curious if this is a true issue with this tractor or HST's in general. The hydraulic cooling system as it sits is a tube array about 3/4" in front of the radiator with no discernible airflow. This and the heat of the HST are the same with the engine cowling on or off.

So, should I look into an actual oil cooler instead of the stock bent tube array? Should I leave the oil cooler and instead stuff a large fan in there to move 2x the air? I know my hydraulic oil won't shear below several hundred degrees, but how will the actual HST fare with high heat? Do they fall apart like a automotive transmission? To note the oil hasn't burnt or discolored - Its brand new Syntractor III.

Sorry for the novice questions - I love tinkering with machines but tractors are new to me. I need the wisdom from the people here before I upset my wife by breaking our only tractor.

4570Man · Jul 5, 2016

Can you post a picture of the oil cooler? My B7100 has an actual oil cooler, but the fins are pretty bent up so I doubt it does much good.

TNGP · Jul 6, 2016

The black tubes is what is supposed to pass as a HST cooler.

bdog · Jul 6, 2016

Does it not have any kind of temp gauge or warning light? I have got the hydraulics hot on my full size backhoe when working it hard in 100 degree weather. Extra cooling can't hurt but you really don't know if you need it or not without knowing the temps.

TNGP · Jul 6, 2016

It does have a temp warning light, but I haven't checked the sensor. I'm sure it's working but I don't know for sure. Would it be wise to nip it in the bud with a cooler or let it be and see if the light comes on? I've got to get myself a temp gun....

jeff9366 · Jul 6, 2016

You should discuss this with your local Kubota dealer, familiar with both your tractor and your conditions.

bdog · Jul 6, 2016

A temp gun would be cheaper than adding a cooler. Don't get me wrong a cooler is never a bad idea but you may be trying to fix a problem that doesn't exist. With no way to measure the temp and no warning lights going off your tractor may very well be operating right in its normal range. Tractors are designed to work and with no signs that it is overheating it probably is ok.

TNGP · Jul 6, 2016

Jeff, bdog - you've both got a good point. I don't trust my local Kubota dealer after thy delivered a used tractor they were trying to sell me as new (After the second part rusted off and allowed the entire deck to drop they were more willing to talk). So I'll have to rely on this forum for tractor intel. There really is no way to feel temp - I'll have to invest in a gun. I've been needing to anyway.

Thank you all for the replies.

jim44 · Jul 6, 2016

I would think that the "no discernible airflow" through your radiator might be a good place to start. If the fan is working, it should be sucking plenty air through there.

flusher · Jul 6, 2016

My 2005 Kubota B7510HST was very prone to overheat if the radiator air passages were more than about half clogged with debris when brush hogging my 7 acre place. An easy thing to check and fix if that's the problem.

Good luck.

AxleHub · Jul 6, 2016

I'm a little confused. The picture of your radiatir shows no fan. The kubota bx models use a forward cooling system I like well . . Does the b series unit you have system use the same thing? If so . . The fan is "behind" your radiator as would be the screen to keep the radiator clear of debris.

Have you cleaned that screen and any buildup that is on the radiator ?

Zooming in on your pucture I see what looks like a screen directly behind your hydro cooling pipe run . So maybe the fan is somehow behind that and thebradiator ?? If so you have very poor air flow because the battery blocks the way for air flow to a significant degree.

Does your engine temp gauge get quite warm indications ?

Remember . . If you have a front flow system then the picture you supplied is of "the back" of the system and not the front of it. And if you have a front push system like cars and some tractors . . how is air flow getting a good chance to cool your unit with the battery right there ??

TNGP · Jul 6, 2016

I should have specified. The air output of the fan is throwing air, but it's not pulling it over my hand from the front. To compare it, if you put your hand in from of a full size truck radiator, you'll feel the air flow over your fan in front of the radiator.

But, I did check the debris trap and the actual radiator finnage. Both are clear. I'm thinking maybe just an inadequate fan design compared to today's fans.

TNGP · Jul 6, 2016

So the black tubing is at the very front of the tractor. Behind it is the debris screen then radiator. The fan is a puller type behind that and is run by the engines pulley system.

Everything is clean and clear in the radiator and debris grill all the way out of the tractor grill. I'm wondering if the battery location is causing the issue like you said. The battery only leaves about 1 inch or less to the radiator...

I've been debating a battery relocation to get the weight further upfront, possibly in the brush guard I need to have made.

buickanddeere · Jul 6, 2016

A laser gun temp reader was an improvement back in the day. Now infrared cameras that plug into smart phone are low cost. The display allows the operator to find hot and cold spots a laser gun can miss. An image can be stored and actual temperature at the crosshairs recorded .
150F can feel hot to the hand yet the oil is barely warmed up.
Radiators that look clean but still have plugged fins are all too common. Worn fan and alternator pulleys with a glazed belt is the norm as most are not tightened until over heating occurs and after wearing out. A new belt can be cranked down tight enough to not slip on worn pulleys however bearing life will be shortened.

aczlan · Jul 6, 2016

If you put a light on one side of the radiator, can you easily see through the radiator fins? You might not be getting enough airflow through the radiator to cool the transmission cooler.

Aaron Z

TNGP · Jul 6, 2016

I checked it and it was fine. You can see through it. I went ahead and sprayed it with the hose the best I could in all the nooks and crannies, but I think the fan just doesn't have enough suction for cooling in hot weather. I've got computer fans that push 240cfm and it feels like more air then the 10inch stock fan.

prichard · Jul 6, 2016

This is not adding up. Your engine temp guage is normal, your trans temp idiot light is off. What's the problem? Doesn't sound like there is one. If the fan was inadequate your engine temp would be high.

Grandad4 · Jul 6, 2016

Your radiator looks plenty clean. The fact your engine doesn't seem to be overheating suggests there's sufficient air flow. One thing not previously discussed is your operating practices. You mentioned using low range for some of your heavy work but have not commented on the engine rpm range being used. If you are under-revving the engine, it can force the HST and other hydraulic functions to operate with insufficient flow of hydraulic fluid. This will generate heat and is not good for the hydraulics. Keeping the rpms high enough to provide adequate flow will improve operating efficiency and minimize the potential for damage, particularly when working the equipment hard.

And without specific temperature information, having your HST lines feel generally about as hot as the radiator under those conditions is about right when doing hard work.

TNGP · Jul 6, 2016

Yep. Those are all the parts. The "idiot" light isn't on - assuming the sensor is still in calibration after 12 years. The engine doesn't overheat based off that sensor or light. The problem is the HST cooling. The airflow doesn't seem to be adaquate to cool the HST. While 150F is hot, I can grab and hold 150F items. The HST feels hotter than that. But with that said, I do need to get myself a thermal camera for my smart phone so the Temps are just speculation...