B7500 steering hiccup

[chim]

B7500HST w/ 73 hours - Had a big day today for seat time. Filled in a large low spot, cleaned a drainange ditch and mowed a couple acres. Toward the end while mowing, the steering got heavy and kinda jerky when turning for a minute or two. I stopped and turned the wheel lock to lock a few times and it was normal again, figuring somehow some air got in a line. Anyone else have this happen?. Thanks,.............chim

 

[Bird]

Chim, that sounds like the same thing I had happen twice (but only twice) with my B2710 before it had many hours on it. Both times was mowing with a brush hog, running PTO RPMs as fast as it would run in mid-range, very hot weather, and after I'd been running continuously for a couple of hours or more. I talked to a dealer about it and the only thing he could think of was possibly needing the hydraulic oil filter changed, but it was such a momentary thing that I never did anything about it, and changed the filter on the regular schedule.

 

[chim]

Thanks Bird. It was surely hot here today, and both the tractor and I put in a full day. Actually the Kubota worked a lot harder. When I finished up and dropped the RFM, you could feel the heat on the end of the PTO shaft. I pulled the hydro dipstick and the fluid didn't smell like it was toasted. The engine heat ran in the low end of the gauge all day. All the filters and hydro fluid were changed at 50 hours. Thanks again..........chim

 

[chim]

Update. The problem arose again this Spring. It was even pretty predictable. After an hour or so at PTO RPM pulling the RFM, the steering would get stiffer and feel like it was kinda pulsating.

I decided to do a full service at 200 (OK, 204) hours, including hydraulic fluid even though it was premature according to the owner's manual. I switched to Super UDT this time. So far so good. The tractor has had a few good workouts since the change, and the feel of the steering hasn't changed a bit when it got good and warmed up.................chim

 

[snowman]

That happens to me every once in a while - same conditions that you and Bird describe - usually after 3 or so hours of mowing in very hot weather, the steering will feel "lumpy" and act as though I lost the power steering. Has always been fine after it's cooled off.

 

[jhburke]

I have a B7500HST also and on real hot days in the past. after about 2 or 3 hrs mowing the steering would act like the power steering quit. I would raise and lower the fel and it would pick up again.

 

[chim]

It seemed to be heat-related. I forget what temps I read, but I shot the temp of the hydraulic fluid cooling coil with an infrared digital thermometer one time this happened. I kept the tractor running, sprayed the cooling coils with water until the temp dropped, and all was well.

This reinforces the importance of keeping the screen in front of the radiator clean. Part of my regular maintenance is taking an air hose and blowing the radiator itself clean

It could be that operating the FEL (assuming it had only been along for the ride) mixed the dormant (cooler) hydraulic fluid "stored" in the cylinders with the hot hydraulic fluid and knocked the edge off the temperature....................chim