How hot should a hydro get during normal use???

KubotaSteve · May 17, 2004

I was mowing some tall grass the other day with the 60"MMM with my 7800 and I was wearing shorts and could feel heat coming from under the tractor. It didn't burn me but it didn't seem quite right. The when I finished and went to spray off the mower deck I hit the rear end with some spray and it turned into steam. I couldn't touch the rear end with my hand it was that hot. I was finished for the day so I put it away. I got it out the next day and it ran fine. The tractor has about 80 hours on it and I did the 50 hour maintenance. The grill and screen in front of the radiator both were clean. The brake was not set, the fluid level was fine and the temp. guage was not reading hot. Although it was very hot and humid outside when I was mowing and I was mowing very slow in medium range and then went down to low range. Am I just overreacting maybe ???? Any ideas???? This is not an open forum for the gear guys to climb up on the throne /forums/images/graemlins/grin.gif

NIXON · May 17, 2004

Steve , You bring up a darned good question ! While I can't answer it ,I'd like to know if anyone has found a way to monitor trans/oil temp . John

_RaT_ · May 17, 2004

I don't know that there is any limit to how hot it can get other then to the point of boiling over similar to that of a automatic transmission fluid. There is no question it will get very hot. I have found that on my L48 it got incredibly hot when pulling my box scrapper uphill. On my L3830, it doesn't seem to get as hot. A while ago, a poster named MChalkey posted his temperature findings using standard UDT and then Amsoil synthetic hydraulic oil and get an appreciable drop in over all temperature. Too hot to touch is not unusual. Even geared tractors will have that since many use the hydraulic fluid that opearates the loader etc in the transmission. My International does.

Bird · May 17, 2004

You know things don't have to be a real high temperature to be too hot to hold your hand on them. I even had one dealer tell me if it doesn't discolor the paint, they don't worry about it. I can't go along with it quite that far, but 100 degrees Farenheit over the ambient temperature is to be expected. I used a thermocouple probe through the dipstick tube to measure the temperature of the hydraulic oil in my B2710 a few times. And I can assure you if it's 180 degrees, you ain't gonna keep your hand on it very long. I doubt that you have a problem.

TNCHRIS · May 17, 2004

checked my L3830HST after mowing for about two hours. 120 deg f. i know thaat on industrial machinery that is usally the goal for temp. i run med range full pedal mostly. this also gives more flow through cooler,so if low is fast enough run low, it's less load .

_RaT_ · May 17, 2004

Chris, my L3830 HST also seems to run exceptionally cool. I have found for whatever reason, that in high range, I have far more power then my Kubota L48. My L48 had loaded tires and planetary gears in the rear end, more overall weight, but it also had one more cylinder. With the L3830, there are times when I'm mowing that I actually forget to shift into medium from high and do not notice it. It can easily happen since whether in medium or high, I'm always feathered on the pedal. I cannot mow my place for example in medium with full pedal. Obviously, I could never mow in high with full pedal although at times, it would be nice. At any rate, the L3830's HST does seem to be, besides an incredibly smooth hydrostatic drive, a very cool running one as well. Having tried those from other manufactuers including the JD eHydro, I'm still convinced, there is no match to it.

Slamfire · May 17, 2004

You can't hold your hand on any surface that exceeds 130 degrees farenheit. The real question is how hot does the oil get, it loses lubricity when it exceeds 120 degrees.
Your heat tolerance may vary, but you can find out what it is by playing with your wifes oven. /forums/images/graemlins/wink.gif You needn't worry about damaging your hand scalding temp is roughly 160. 180 is about where you'd expect a solid babbit bearing to wipe, babbit material flashed on a steel surface hold up better, I guess the steel moves the temp away from the babbit quicker.

ns_in_tex · May 17, 2004

I read somewhere, it was desirable to keep hydraulic fluid 200 degrees F and below. Above that it may start to break down.

If you happen to have an infra red temp gun, you could check it with that.

grandad · May 17, 2004

Kubota shop manual mentions operating temp for the HST is 50 - 60 deg C, or 122 - 140 deg F., so that would probably be an average to go by. Under heavy load it would go up from there; with cold days and light loads it's less. There was a thread in the fluids section a while back about how hot HST juice could get before breaking down... seem to remember 200 deg F.

If the rear end was so hot water turns to steam on it, something is either way overworked or not working right.