deere 35d slow hydraulics when running mower

[jsw development]

My 35d has developed an issue when running our mower. After mowing for a few hours, it gets to the point that when mowing and swinging at the same time the swing or boom is super slow. Curl is fine. I can't figure out if I'm having an issue with priority valve or if it's purely a heat issue. If I stop the mower my functions return to normal speed. Also, we've got several hundred hours running this set up and this hasnt been an issue before.

Any thoughts?

 

[mg2361]

First, need a serial number. Also, if the mower is off and you dig with a bucket how is the performance? Does it mistrack at all in either high range or low range?

 

[jsw development]

s/n 1FF035DXEA026537

With no auxiliary it performs normal. I can't tell if the boom and swing has slowed. I't doesn't mistrack at all.

 

[mg2361]

Try testing cycle times (see attached). It is not a substitute for a flow test but will give us a general idea if there is any obvious hydraulic issues. Let me know if anything is way off.

 

[jsw development]

Thank you sir!

Dumb question, is “high idle” pegged or in the green shaded area on the knob? Is this performed with no bucket? I’m guessing my 650lb mower would affect my times

 

[jsw development]

Oops double post

 

[mg2361]

Fast idle would be all the way up. Yes, cycle times would be with a bucket. Mower would definitely affect the times.

 

[jsw development]

Fast idle would be all the way up. Yes, cycle times would be with a bucket. Mower would definitely affect the times.

Was able to check my cycle times today and I’m within spec on each. I’m beginning to think that while running the mower something is causing excessive heat to build up in the hydraulics. My machine doesn’t have a gauge for hydro temp.

I have 400 hours on the current hitachi zinc free fluid and filters.

Cooler is clean. Any ideas on where to go from here?

 

[Tones]

A infra red heat gun would be good to have here. To determine if it is indeed a heat problem work the machine with the bucket to get a reading at operating temp then work the mower and take another reading.
Does the oil return from the mower go through the cooler or directly to the tank?

 

[mg2361]

get a reading at operating temp then work the mower and take another reading

Do what Tones said. What position is your auxiliary selector valve in? One way flow or two way flow? If it is in one way flow it will not run through the cooler from the mower. If it is in two way flow it will go through the cooler. Is there a back pressure limit to the mower? If there is you may have to use one way flow. I would also check the system pressure for pumps 1,2 and 3 with the machine at operating temperature.

 

[jsw development]

Tones- thanks for the response. I have an IR gun so I will definitely give it a shot.

Mg2361- really awesome of you to post the diag info, thanks for sharing. I’m hoping I just have it in one way flow but I honestly can’t remember the last time I messed with that valve