A question not only for the tech's in the know, but looking for experiences from anyone. I've noticed on my Deere 850J that my ripper cylinders would bleed down slightly overnight. Maybe about 6" or so. I ran an experiment several times and left both the ripper and the blade in the full up position and come back the next day to find both had bled down some (I don't have exact measurements). I usually "unload" the hydraulic system after shut down per the operator's manual and the blade and ripper had lowered slightly overnight. I also left the blade and ripper up without unloading the hydraulic system and same thing after a day or two--they had sagged down. Is this normal and to be expected? If normal, how much is acceptable? This is kind of related to some concerns I had last summer while working the machine in the heat of the day (105F) where I saw hydraulic temps 203F to 206F. The hydraulic analog guage never did get into the red, but it sure did ride the high limit of the green zone. I confirmed the guage with the on board diagnostic live values and an ir thermometer. I never triggered an alarm or derate, but I didn't feel comfortable going any further than this so I'd just rest the machine at 1600 rpm for about 20 minutes and get the hydraulic temps back to about 165F then continue on for about an hour or so until I had to repeat the process. Since our temps run in the 100's plus for weeks at a time where I'm located, I just found it easier to run until 1 or 2 o'clock and then just call it quits for the day. Thanks for reading
Serial number? There is always some normal leakage past the spools. The maximum spec for the lift cylinder drift is about 4mm/minute with the oil at 150*F. A cold machine the rate would be slower.
Leaking down overnight is well pretty meaningless implements are always on the ground when you park The hydraulic temps I would start with making sure the cooler and radiator are extremely clean though I am not familiar with that model every other machine I have seen has an incredible amount of dirt oil and leaves restricting airflow usually some components have to be removed to properly clean coolers
Serial no. TO850JX169801
Thanks for the reply. I don't notice any cylinder drift while I'm operating. I purposely left blade and ripper up to see if it would give me any insight as to whether I had an unusual hydraulic bypass issue. As for the coolers (charge air, engine, and hydrostat--there is no hydraulic cooler on this machine) they are very clean and maintained daily. As such engine, hydrostat and fuel temps are running moderate even in the most severe heat and humidity pulling a 11.5' root plow or pushing a very heavy 14' root rake. Belly pan and general machine is kept very clean. I'm wondering if relatively high hydraulic temps are just the nature of this beast in these conditions.
The hydraulic oil doesn't start to bread down until you get into the 240 and higher temps. What you are running is warm and you are probably helping things by letting it cool. Cylinder drift is normal and is usually given a spec of how far an implement drops in a minute. A small amount of oil needs to get by the packing in order to lubricate it. Over time clearances will loosen up as well and you get some leakage by internal components of the valving as well. You can measure the rate of drift now and use that in the future to see if the problem is getting worse.
I had Google'd hydraulic temps a while back and could never get a clear answer. Some articles suggested that damage starts occurring at 180F, but I can't really wrap my head around that because I see 180+ regularly on my ag tractors, skid steer, and all sorts of equipment. I had also read the heat limits of hydraulic fluid (I use JD Hydrau per JD recommendation) and although the fluid is likely to tolerate the temps I'm seeing I was always more concerned with the long term effects on the pump and system seals.
The oil cooler bypass valve will not send all the hydrostatic oil through the oil cooler until Hydrostat oil temp reaches 187*F. If your coolers are clean and free from debris, fan speed is where it should be and your engine temperature runs normally, then I would just double check that the oil cooler bypass system is functioning correctly. But to hit 200* oil temp on a 105* day working hard wouldn't surprise me.
It all goes to show that you shouldn't believe everything you read on the internet........... The alarms on most equipment for high hydraulic temperature (those that have such alarms installed I mean) usually don't start sounding until the oil reaches a temperature somewhere North of 120-130C (245-265F). Many alarms even have a time delay where the temp has to be at or in excess of the set value for a certain length of time before the alarm will sound.
My machine has a separate hydrostatic system for the 'transmission', but there is no cooler for the separate hydraulic system. I have never seen hydrostat temps which concern me. They are always what I'd deem quite moderate even in high ambient conditions. My hydraulic system, however, is described as a convective sump and there is no cooler for this system. The hydraulic system is the only place I'm seeing the 200F+ temps when it gets really inhospitable outside. Engine, fuel, and hydrostat temps look really nice.
Do you think running the machine when my hydraulic temps are in the low 200's will have some long term effects on pumps, seals, etc...?
I have no experience of the particular model you have, but provided that "low 200s" is no higher than say 215-225 I would say there is little chance of long term effects. I would stand corrected by Deere SMEs on that though.
Under 210F on a hot day doesn't seem unusual. I think hyd's. can generally tolerate a little more heat than engines. The hyd. reservoir on my skid steer gets pretty hot to the touch but has never set off the warning light. I think it's major contributor to the paint coming off though. Could be a cheap paint job too as doesn't appear much primer was used when it was built.
Yeah, my hydraulic reservoir gets really hot, but Deere must have done a good job with the paint because I haven't seen any effects yet. In the middle of the day you can't even think about touching the reservoir or the cylinders. Then again, I've darn near burned my hand trying to pick up a wrench that's been laying out. Also, must use grease gun in morning only because if you leave it out all the grease will melt and drain out of it. I shot the grease gun with the ir thermometer just for kicks and it was 140F or so if I recall.
Has anyone tested the hydraulic main relief valve pressure to make sure it is not set too low? That would heat the oil up excessively. Deere usually considers Hydraulic or Hydrostatic oil overheating at >212*F on crawlers.
I think I will look into this. Thanks
More specifically, perform pump load sense and pump cutoff pressure checks. System relief check requires an external electric over hydraulic pump to perform the test. If pump cutoff is to spec (or can be adjusted to spec) then system relief will not have to be done.