Hydraulic area "steaming"

ironpen · Sep 18, 2012

I was washing off clippings from my TN 75 New Holland and noted that when I wet the hydraulic area below the remotes that it steamed like it was very hot. I had not really been using the hydraulics for anything other than raising the finishing mower and driving about an eighth of a mile. The hydraulic system was not doing anything during the work time. Is this normal??? I have never noticed it steaming before when I rinsed off the tractor. TIA

boggen · Sep 19, 2012

no clue about your tractor. if it is an open center design for hydraulics. then hyd oil is constantly flowing from the hyd pump through all your hyd valves, then back to the hyd tank, then back to the pump and just repeats and repeats.

if you have some sort of clog or pressure relief valve going off. these things can cause extra friction which can cause hyd oil to heat up quickly.

if your tractor has a "hyd oil cooler" it may be plugged up... a hyd oil cool likes much like a radiator. but instead of antrifreeze / water going through it, it is hyd oil. the hyd oil cooler may be up front and perhaps buried under various things and may not be see able until you start removing a panel or like.

double check your hyd oil filter as well. to see if it is clogging up.

without saying double check all your fluid levels.

ironpen · Sep 19, 2012

Thanks, I will blow out the radiator area (three sets of coils...they don't look particularly dirty, but that is a good suggestion. Fluid level is ok. Do you think I should get the dealer to come look??

k0ua · Sep 19, 2012

Why not get a laser thermometer gun and check to see what the temp actually is.. I would think anything up to 180 degrees is OK. I have heard it said that hydraulics can operate up to about 100 degrees above ambient temp. So if it was 80 degrees up to 180 would be probably on the high end of OK. Anything above that I would think might be reason for concern. Here is a link to a temp gun, There are lots of places to buy them including home depot. harbor freight etc.

Amazon.com: HDE Temperature Gun Infrared Thermometer w/ Laser Sight: Home Improvement

James K0UA

jinman · Sep 20, 2012

Most hydraulic oil can easily handle temperatures above boiling. It deteriorates rapidly above 250 F. I find my reservoir heats up to about 185 F or a 100 degree rise over ambient. If it was cool outside, what you may have been seeing is simply normal condensation of warm/hot vapor. I would make sure that the hydraulic system isn't under load and also get yourself one of those non-contact IR thermometers as James suggested. Knowing the exact temperature puts a lot more credibility to your discussion with your dealer if needed.

J_J · Sep 20, 2012

I would venture to say that hyd fluid would be OK in the 180 to 200 degrees, and anything above that for a long period would start to break down the fluid.

One thing I am thinking is that you may be working at the relief pressure for long periods, and if a valve stays in relief very long, the fluid will definitely heat up.

If you can't find the cause of the heat on the fluid, then you can add a small fan powered hyd radiator.

We use them on our PowerTracs.

Fluid exposed to high temperature can experience permanent deterioration. For example, a substantial reduction in fluid viscosity normally accompanies asperity contacts (mechanical rubbing) and an increase in temperature. In addition, irreversible viscosity change can also occur when a fluid having poor shear stability encounters high temperature. Whether through rapid oil oxidation promoted by high temperature with its accompanying sludge formation production, or simply accelerated component wear, the influence of high temperature on oil properties is serious and generally deserves prompt consideration and attention.

ironpen · Sep 21, 2012

I thoroughly cleaned the hydraulic system radiator yesterday. It is pretty large...maybe 14 x 20 inches. It's the first of the three radiators the air sweeps through. It wasn't all that dirty, but there was some debris. The fluid is not discolored. I am not a hydraulic expert....how do I know if I am "working at relief pressure for long periods"? TIA

J_J · Sep 21, 2012

If you would install a 3000 hyd gage in the IN port of the FEL valve, you can see the pressure that the hyd system is producing.

Some people leave the 3pt lever in the up position and the 3pt is then relieving. The 3pt lever should be in the neutral position.

Any valve you activate and operate the cyl, you can see what pressure the cyl's are developing.

With a light load, the loader might only show 500 to 600 lbs, and if you are filling the bucket with gravel or dirt to max, you might be working at the relief pressure of say 2750 psi.

If you are just driving the tractor, and not using the cyl, the hyd system should not be that hot. If you have a Hydrostatic tractor, do you have a separate tank for the hydro fluid, or does it use the single tank fluid?

About 180 to 200 degrees should be max, although the fluid can go higher. At high heat, the fluid will deteriorate faster.

You could also add a temp gage to the hyd system.

Also, with all valves in neutral, there should be very little pressure in the hyd system.

muddstopper · Sep 21, 2012

On my old tn75, I had three hydraulic valves. One for the FEl, joystick type, the stupid electric for the three point and a third for aux. The aux was cable controlled. Time to time I would bump the cable lever and have the aux partialy engaged without anything being hooked to the aux circuit. This would cause the hyd oil to heat up and really effected the FEL. If your tractor has the same lever cable setup for your aux circuit, you might want to wiggle the lever and make sure it isnt partialy engaged.

ironpen · Sep 22, 2012

I do have a joystick, but no FEL. I only use it to raise my bushhog up and down. I have not be using the bushhog as of late. The day I noticed this I was using a finishing mower...3 point hitch type that sits on 4 wheels and the arms are all the way down. I guessed this to mean there should be no hydraulic pressure being used. I have a flip switch in the cab that raises and lowers the 3 point arms. I did raise the mower (1300 lbs.) and drive it home (1/8 mile) with that switch in use. When I called the dealership, the shop told me that because I have an electronic shuttle, this also works on the hydraulic system and that my PTO also works from the hydraulic system. I did not think of that....but thinking back, I did have a hydraulic leak a while back and the tractor would not move. Put some hyd. fluid in and it moved normally. I have had no problems with leaking since they replaced a seal and it does have normal amt. of fluid in there now. The tech wanted to know how hot it was and I told him I did not know, but the water wasn't sizzling like a pan of bacon grease, but a fair amount of smoke was produced and this happened for several minutes every time I sprayed it with some water to see if it was still doing it. I was afraid to put a whole lot on it for fear of cracking the case. Sum it all up by saying I still don't know if I need to pay for a service call or if I am making a mountain out a molehill.

Answering JJ's question I only have one hydraulic reservoir.

Mudstopper, where is the cable that controlled you aux input?