Hydraulic system temp monitoring?

jimgerken · Aug 22, 2007

On a compact tractor, how hot (maximum) should the hydraulics ever get? Or, what is normal range? Where and how (what instrumentation) would a person use to monitor this? I am using stock fluid in a JD 2520. I see it is red in color when viewed thru the sightglass. However, when I top off the level 'cause I added a valve and a couple cylinders, the John Deere brand recommended oil is more like the usual engine oil color. Is this 'cause the tractor came from Japan and has something different in it? Obviously it is compatible, or John Deere would recommend something else. I don't use the low-viscosity hyd oil, just the regular stuff they sell for transmission/hydraulic systems. thanks! for any info you can add...

kennyd · Aug 22, 2007

You could get a transmission oil temp gauge like THIS one and plumb it in to one of the test ports in the tranny with the right adapters. As far as max temp-I would guess at about 200° or so...have to check the manual on that one.
My dealer told my the original fluid is red because it's easier to see leaks when the machines are new, I can't verify that but that's his reason.

dfkrug · Aug 24, 2007

I did not know the JD OEM (Hygard?) fluid is colored. Colored
fluid is great.....not only is it easier to tell what is leaking, but
it is more visible on dipsticks and sight glasses. I use redish
Chevron 1000 THF.

I, too, would like to know what hyd fluid temp is too hot.

Mahana79 · Aug 24, 2007

I cant really give a pinpoint number but i can tell you that on our aircraft the Hyd fluid (MIL-83282) overtemp switches are set at 165 F Not sure how that fluid matches up to the JD stuff though

I would probably be under 200 F for sure

jdbower · Aug 24, 2007

It's hard to say what the right temperature is. Like the coolant temperature for cars it really depends on make and model (my current truck runs much hotter than my previous one by design). You may be best getting the temp gauge and then noting the temperature if the red light comes on. I've only had mine come on once, while mowing on a hot day when clippings blocked the front grill. I'd also just take a baseline reading when at normal operating temperatures and start paying close attention if it exceeds that value by whatever safety margin you want (I'd think around 10 degrees or so).

john_bud · Aug 24, 2007

My old Ford has the lift specs for full load at a fluid temp of 160F. It's pretty normal for hydraulic fluid to be 100F hotter than the ambient temperature.

If you are working the tractor hard, the housings and such will get hot to the touch. Uncomfortable to hold your hand on for more than a few seconds. If you get over 212f, you are too hot and either have a problem that should be fixed or are in Death Valley!

On the other side, if the temp does not get to 160F when working, it's likely you won't evaporate out any water in the system. (Condensation, washing, leaks from rain, etc). Water in the oil will ruin a tractor faster than a slight over temp. Your quest to add a guage to remove doubt is a good one.

jb

jinman · Aug 25, 2007

jimgerken said:
On a compact tractor, how hot (maximum) should the hydraulics ever get? Or, what is normal range? Where and how (what instrumentation) would a person use to monitor this? I am using stock fluid in a JD 2520. I see it is red in color when viewed thru the sightglass. However, when I top off the level 'cause I added a valve and a couple cylinders, the John Deere brand recommended oil is more like the usual engine oil color. Is this 'cause the tractor came from Japan and has something different in it? Obviously it is compatible, or John Deere would recommend something else. I don't use the low-viscosity hyd oil, just the regular stuff they sell for transmission/hydraulic systems. thanks! for any info you can add...

There was another thread about temperature and measuring it, but I don't remember where. One poster used an IR thermometer to measure the temperature fluid lines coming out of the hydraulic pump and also the reservoir temperature. His maximum readings were 160ｺ to 185ｺ after several hours of work. Naturally, the oil coming out of the pump had the highest temperature.

I did some research on the subject of temperatures and found an article that did testing. They said that oil over 200ｺF would deteriorate at twice the normal rate and over 250ｺ would lead to complete failure in a few hours. Skydrol is a brand name of a fluid used in aircraft hydraulic systems. It will not deteriorate at much higher temperatures than other oils, but I believe it also should not be used at constant temperatures above 200ｺF. It is also reddish-purple in color.

Mahana79 · Aug 29, 2007

jinman said:
Skydrol is a brand name of a fluid used in aircraft hydraulic systems. It will not deteriorate at much higher temperatures than other oils, but I believe it also should not be used at constant temperatures above 200ｺF. It is also reddish-purple in color.

that Skydrol stuff is pretty nasty stuff. we use a version of it in some of our equipment (MIL-H-17111) Our version is completely clear when new but turns a yellow/amber color after the least bit of use. it has a very high thermal expansion rate and will eat a normal hydraulic hose up in a matter of hours. They must have a synthetic liner in the hose. if it develops a small leak (less then 60 drops per minute dynamic) it will actually start to congeal and will seal itself. I try to tell the new guys to leave the s crusty looking scab on the actuator rods and it will be fine. they wash/wipe it off and it starts leaking like crazy!!!!!!!!! Rebuild time!!!!!

probably no help but some gee wiz info