JD 455 mower and hydrostat

[DavebPt]

Just developed problem with a 455 we have had since 1998. This is a diesel with 60' mower and hydro static drive. It just started yesterday with the mower losing revolutions and the tractor slowing to near no movement and then surging forward with the blades turning normally. Any ideas of where to start looking? Engine never stalls or slows down.

Thanks,

Dave

 

[beenthere]

First question, has the tranny fluid and filter been changed ??

 

[DavebPt]

It has been several times since I've owned it. Just added about a quart of fluid with no improvement. PS also not working now.

 

[tomd999]

Hiya,

Sounds like a plugged suction filter or a low fluid level for the easy to fix solutions, however, the more expensive to fix reason could be a worn or stuck piston in the charge pump. So, how many hours on the unit? Being a '98 there should be somewhere around 1600-2400 on the unit if it's seen average use. (100-150 hours per year) well within the expected life of the 455 transaxle if taken care of well. What fluid did you put in last change? IIRC, the K91's take somewhere around 2 gallons of fluid, did you check the level and it was low before you added a quart or did you just dump it in hoping that was the issue? Did you "bleed" the system if it was low before you added the fluid? if it was low enough, it may have put air in the lines and components. I know the "bleed" procedure for the older hydrostats was to drive it around making slow figure 8's to purge the air from the steering box and to go forward and backwards several times. (They have electric clutch PTO so that was never in the procedure so you would need to disconnect your PTO shaft and then cycle the PTO several times to clear the air then reattach and test again.

Hope it's the level and sucking air and not a charge pump issue,

Tom

 

[DavebPt]

Machine has about 1100 hours. I use the JD fluid from JD. It was about a quart low that I found when checking; first thing I looked at. Thought I'd change the fluid and filter and see what happens. THanks for the help.

 

[DavebPt]

Is there more than 1 filter? I have been reading about a screen that needs to be cleaned. Any idea where that is if there is one?

Thanks

 

[beenthere]

Should be a filter on the transaxle and one on the engine... makes two.

 

[tomd999]

Hiya,

Your 455 should have a TuffTorque K-91, here is the K-92 service manual link. They should be close enough that you should be able to get by.

https://www.tufftorqservices.com/EnvEEdefault/FlatHTML/TechInfo/docs/manuals/k92.pdf

Starting on page 44 is the hydraulic test port location and the troubleshooting guide. Follow the guide and you should be able to find whats wrong. You may have to purchase a pressure test gauge to do a complete test. After looking quickly I had a thought that you may have a relief valve spring that broke lowering the overall system pressure or one of the check valves for pushing the tractor manually may be partially open.

Good luck,

Tom