L5240 hydraulic oil overheating with JD MX8 mower

[lylesings]

I have L5240 tractor with HST. I'm using a John Deere MX8 8 foot rotary mower, semi mount version (so tractor does not need to lift it off the ground). JD specs says minimum 40HP to operate & it weighs about 1700 lbs. It's a fairly big implement. When I run this with tractor rpm at 2000 and PTO 400-425 the hydraulic oil overheats & comes spilling out of the safety/pressure relief valve located in bottom center of tractor after about 1.5 hours of use. Grass is light to moderate thickness; definitely not too heavy to cause a problem.

Is this too much mower for this 50HP tractor? Or is there something else that needs to be addressed? The fluid level is filled to proper level when starting & oil cooler is cleaned of debris.

 

[D2Cat]

Sounds like you have a vent that is plugged, or too much fluid to start with.

 

[Bulldog]

Have you always ran it at low rpm's or have you tried it at 540 pto rpm's.

 

[lylesings]

Fluid is at proper level. Is there a vent other than the one on fluid fill cap?

 

[lylesings]

I used at higher rpm & it overheated even quicker, so I slowed it down on dealer advice.

 

[Jim L.]

Mower greased and lubed? Blades turn freely when off the tractor PTO?

Running at a lower RPM is not a good fix, as the blade tip velocity will be inefficient, requiring more power.

 

[Bulldog]

How heavy / thick is the material your cutting?