Kubota 5030 HST problem

[msi]

My brother brought me his 2005 Kubota 5030 HST to look at. This tractor/loader has 1250 hours on it and has not been taken care of. He makes silt sock for the gas companies and uses this tractor to load mulch into his sock maker. Dusty, dirty conditions.

Here's the problem. If you set the engine to 2000 rpm and take the tractor into a pile of mulch, the rpm's drop to 1200 and the tractor almost stalls. If you let off the hydro pedal, the rpm's come back up. The loader works fine, up, down pressure will lift the front of the tractor up with no engine lug. The only time the engine lugs is when the HST tranny is engaged more than 1/2 way.

So far I changed the fuel filter (very dirty) drained the fuel tank and changed the hydraulic filter (looked like new). I checked all the fluids in the tractor and they look fine and were at proper levels. I called my Kubota dealer and they said to change the hydraulic fluid. 15 gallons of Kubota fluid is $325.00. Kubota recommends changing this fluid every 400 hours and this tractor has 1,000 hours on the fluid. I'm not opposed to spending the money for the fluid, but I just can't see it causing the stall problems?

I am going to hook the tractor to my irrigation pump tonight so I can load the engine with the PTO. I really can't tell if the engine is lugging because of something wrong in the hydro or the hydro is fine and there is a problem in the engine.

So my question is this: Has anyone every fixed a hydro problem by changing the fluid?

Thanks

 

[North Idaho Wolfman]

What about the air filter?
Check for 2 of them (one inside the other).

Yes bad fluid can effect how the HST transmits power, so changing it could improve the situation.
If fluid has never, or only once, been changed in the 1250hrs , then chances are your looking at an expensive rebuild if it has done damage to the HST unit.

 

[msi]

Yep, changed both air filter too.

Thanks-

 

[KubotaFiend]

Hi msi, welcome to ott.


How heavy is this mulch?

What range are you in, low medium or high?

If in med or high, i would put it low and up your rpms.





Ben.

 

[msi]

Hi.

Thanks for the replies.

I took the loader off and have been driving the tractor up and down the road. I set the rpm's to 2,000, tranny is in high gear and I take off. With the pedal half way depressed, the tractor moves fine and the rpm's stay just under 2000. When you quickly and fully depress the hydro pedal, the rpm's drop to below 1,000 and the tractor will stall if you keep the pedal fully pressed. This is on level ground too.

I hooked the tractor up to my irrigation pump (the pump only requires 30 hp to run) and the engine didn't seem to hesitate when the pto was engaged and the throttle was run at speed.

So far I have changed EVERY filter on the tractor. The only thing I haven't done is change the hydro fluid. I have 15 gallons of it sitting in the shop but am hesitant to change it until I have a better idea of what the problem is.

Thanks-Scott

 

[North Idaho Wolfman]

You might want to get the WSM for the tractor, it usually has some specific insight to how to troubleshoot the Hydrostatic unit.

 

[msi]

Hello. Thanks for the replies.

I my neighbor saw me fiddlin' with the tractor in my shop last night so he stopped over. As luck would have it his nephew is a Kubota technician.

His nephew was at my shop within 1/2 hour. As soon as he started it up he said a cylinder is not firing. He took the injectors out and took them to work to test today. He thinks an injector is bad. I hope...

 

[85Hokie]

Hello. Thanks for the replies.

I my neighbor saw me fiddlin' with the tractor in my shop last night so he stopped over. As luck would have it his nephew is a Kubota technician.

His nephew was at my shop within 1/2 hour. As soon as he started it up he said a cylinder is not firing. He took the injectors out and took them to work to test today. He thinks an injector is bad. I hope...

and that would do it - not hitting on all cylinders ! I hope that is your answer !!!

and ......change the hydraulic fluid too!

 

[D2Cat]

msi, never know what will happen when you have your shop doors open!! May your problem be that simple!

 

[msi]

and that would do it - not hitting on all cylinders ! I hope that is your answer !!!

and ......change the hydraulic fluid too!

I own a lot of tractors and know what each one usually sounds like. Being that this is my brothers tractor, I wasn't used to how it normally should sound. I sure couldn't hear a cylinder missing but the tech picked up on it right away.