L45 forward surging, whining

[giannettim]

I recently bought a used L 45 with 2500 hours on it. I’ve done a complete fluid change, and all the filters. (Before I did this the below issues were there)
I understand there is some whining in the HST but this is not your typical whine additionally there is considerable surging (jerking) while in forward gear in LM and H. Also the forward speeds are much lower than they are supposed to be. In medium I’m only getting about 4 mph. In reverse the tractor runs perfect.

Yesterday I replaced the check and high pressure relief valve (forward) assembly And that hasn’t helped. I’m thinking I may need to manually adjust the valve???

I’m looking for any ideas why forward may be messed up.

 

[Ironman2]

I recently bought a used L 45 with 2500 hours on it. I’ve done a complete fluid change, and all the filters. (Before I did this the below issues were there)
I understand there is some whining in the HST but this is not your typical whine additionally there is considerable surging (jerking) while in forward gear in LM and H. Also the forward speeds are much lower than they are supposed to be. In medium I’m only getting about 4 mph. In reverse the tractor runs perfect.

Yesterday I replaced the check and high pressure relief valve (forward) assembly And that hasn’t helped. I’m thinking I may need to manually adjust the valve???

I’m looking for any ideas why forward may be messed up.

The whining and jerking sounds like pump cavitation to me. There is probably a procedure to flush air from the system in the manual.

 

[giannettim]

Wouldn’t that cause reverse to have the same symptoms?
I’m new to troubleshooting this type of stuff so I am just asking.