HST shudder. Transmission problems?

[Justasquid]

i Have an issue I hope someone can shed some light on.

i own a 2008 L4240 HTS. With 850hrs on it.

while traveling down the side of the road at about 14mph, it suddenly lost 2-3 mph and started to shudder. I was only about an 1/8 mile from home so I drove it slowly the rest of the way.

i have only owned this for a few weeks and before this it has been great. O issues. I did change the filters and there was some speckles and a few larger flakes of metal in fluid.

i don’t think it’s engine related as the rpms did not change.

as of right now, if I press The pedal it will move, but it shudders and is not smooth. If I go in a lower range, it seems better but it is still present. It does smooth out once I am moving, but I haven’t tried too many things as I don’t want to run it in case it could cause more damage.

if any one has any information on something to check or advice, I would greatly, appreciate it. I am mechanically inclined for most things, but. I know nothing about tractors and information is very hard to come by

Thank you.

 

[lugbolt]

clutch disc lost it's splines. Take the little bolt out of the bottom of the bellhousing, the one that has a pin in it. On the bolt, is there any metal flake? If so, your clutch needs to be replaced. If not, grab a nice bright flashlight (LED is awesome for this) and look up inside and see if you can see any metal flakes.

if you think it's hst related, remove the hst filter and see how much metal is on it. Some is normal, but if it's plugged with brass shavings, then you're looking at hst stuff.

 

[Justasquid]

clutch disc lost it's splines. Take the little bolt out of the bottom of the bellhousing, the one that has a pin in it. On the bolt, is there any metal flake? If so, your clutch needs to be replaced. If not, grab a nice bright flashlight (LED is awesome for this) and look up inside and see if you can see any metal flakes.

if you think it's hst related, remove the hst filter and see how much metal is on it. Some is normal, but if it's plugged with brass shavings, then you're looking at hst stuff.

Thank you For the reply. I will check the clutch out. I did change the filter and there was a little on the filter magnet but nothing in the filter itself That a could see. There was some in the bottom of the bucket after I emptied the fluid out. Nothing brass though. All shiny silver. Not sure if any of it is magnetic though. I didn’t check that.

Thank you again for the information. I will let you know what I find.

 

[Justasquid]

I removed the bolt and there wasn’t any metal or shavings. I shined the light into the hole and there wasn’t any metal present there either. The hole only goes so deep though. About an inch at most. I couldn’t see past that.

Could it be a pressure relief valve or something I can check? I noticed the when I let of the pedal, it takes about a full second to react, when it normally reacts right away. Also the adjustment for how quickly it reacts no longer seems to work. It reacts the same no matter what.

I am really trying to avoid going to the dealership. I do realize I may have to, but if it’s something I can check into myself, I would rather do that.

Thank you.

 

[rbargeron]

Unfortunately these symptoms sound serious. A shudder that changes with range points toward an issue inside the HST. Was the high-pressure HST filter chaned (or had it been changed recently? Debris in the oil can mean there's damage to the high-precision "slipper" surfaces in the pump/motor set. This kind of failure is pretty rare - but does happen. It gets gradually worse until it fails to drive. The solution is a new HST unit.

FWIW failing clutch disks usually fail completely (no drive).

p.s. I've had an HST apart and seen its internals up close. Hope I'm wrong about yours. Good luck, Dick B

 

[Dave_eng]

This may be a silly question but your comment about recently changing oil and filters caught my attention.

Many times owners on this forum who chose non Kubota fluids and filters ended up with HST performance issues.

Dave

 

[Justasquid]

This may be a silly question but your comment about recently changing oil and filters caught my attention.

Many times owners on this forum who chose non Kubota fluids and filters ended up with HST performance issues.

Dave

Thanks for the reply. It did have kubota filters on it and I also replaced with kubota filters as well. And just to clarify, I changed the filters after the initial problem just to rule out a blocked filter.

thanks for the heads up though. I do generally try to run Oem parts on my equipment.

 

[Justasquid]

Unfortunately these symptoms sound serious. A shudder that changes with range points toward an issue inside the HST. Was the high-pressure HST filter chaned (or had it been changed recently? Debris in the oil can mean there's damage to the high-precision "slipper" surfaces in the pump/motor set. This kind of failure is pretty rare - but does happen. It gets gradually worse until it fails to drive. The solution is a new HST unit.

FWIW failing clutch disks usually fail completely (no drive).

p.s. I've had an HST apart and seen its internals up close. Hope I'm wrong about yours. Good luck, Dick B

That is what I am worried about. As of right now, I’m probably bringing to our local dealer and hope it doesn’t break me. Lol. Thanks for information.

 

[Justasquid]

Just to update anyone interested. It was in fact the HST. it is currently being replaced as I write this. Thank you to all who have offered their advice.

 

[rbargeron]

Just to update anyone interested. It was in fact the HST. it is currently being replaced as I write this. Thank you to all who have offered their advice.

I've thought about this one over the past couple months. 95% of the HST issues reported here turn out to be linkage-related or electrical bugs (with the newer models). Sorry to hear yours was was an actual HST unit failure.

Has the dealer involved the Kubota rep in the diagnosis? It wouldn't hurt to ask them to have a look and see if they might help with part costs. Kubota's HST has a very good track record - and they may offer some support with only 850 hours on the machine.

 

[Justasquid]

I've thought about this one over the past couple months. 95% of the HST issues reported here turn out to be linkage-related or electrical bugs (with the newer models). Sorry to hear yours was was an actual HST unit failure.

Has the dealer involved the Kubota rep in the diagnosis? It wouldn't hurt to ask them to have a look and see if they might help with part costs. Kubota's HST has a very good track record - and they may offer some support with only 850 hours on the machine.

Thank you for your input. You were correct right from the start.

I dont believe a rep has been involved as the tractor is a 2008. It was used for snow blowing and mowing, mainly pto work. The previous owner had a mile long driveway so it’s possible the previous owner may have been blowing snow in high which could lead to overheating of the oil. It was suspected that perhaps the brass plates became fatigued over that period and then finally gave way At least that is 1 assumption right now. but they really don’t know yet why it failed. They also said it is very rare for this to happen and these units are pretty much bulletproof. But heat seems to be something that could cause issues. Certainly something to keep in mind for the future.

As for diagnosis, it failed the pressure testing and they did find brass in the oil. I saw a few flakes initially and not any in the filter. But once everything settled in the oil bucket, after a few days, it was about a teaspoon full. So quite a bit in the oil.

thanks again for advice. I truly appreciate it.

 

[skeets]

I am glad you found out what was going on, and I hope they can get it back to you in jig time,, Please keep us updated