3ph raises then drops suddenly-3720

bmaverick · Dec 10, 2023

fishhead said:
interestingly i notice that the machine is slightly faster today- 6.9 vs 6.2 yesterday under same conditions and feels much better. Guess the lesson is to keep the fluid up oil the upper half- I wonder if somehow the dipstick is off or something?

Yanmar and Deere developed the J20B, J20C and J20D hydraulic fluid specification together.

I buy the local farm box store brand licensed for the J20C. Made by Ashland-Valvoline.

This way, it works really well in our Yanmar made machines. The universal fluids work OK for a few weeks, then they go crappy. So, just stay with the correct 'meets' J20x and all is good.

fishhead · Dec 10, 2023

thanks

careyo63 · Dec 10, 2023

Check your manual for a filter. If it gets dirty it will prevent the fluid from passing through it. My old Hyd. filter is a round metal tube made of screen material you can remove and clean it. BTDT for the exact reason your describing. Esp. when Temps. got cold. After I corrected that a stable problem showed up and it was Lift handle spring/gasket was bad. It would drop ever so slow until the control valve pick it up and raised it. After repacing the washer the handle stayed in place and the linkage stayed snug against the control valve pin .

beenthere · Dec 10, 2023

fishhead said:
was using the back blade to clear some snow this am and i noticed that every once in a while i would raise the back blade and i would come up to full height then drop a small a mount suddenly and catch again. Fluid levels seems fine and fluid is clear. All other operations seem normal. This just started this am.
Thoughts?
Thanks

Sounds like the rockshaft linkage adjustment is not correct.

Catenary Kid · Jan 15, 2024

I have a similar issue with my 3720. With an 80" snowblower attached (it's heavy - maybe 900# or so) I raise it to any height at any RPM and the 3 point will drop maybe 1/4" (not sure, haven't measured it) then catch and immediately go back up, repeatedly. About once ever 20 seconds. It moves so little it is easier to hear it than to see it. Fluid level is clear and full. Is this a leak in the lift cylinder, and is that repairable without tearing the back end of the tractor apart? Many thanks...