Mowing Kioti DK55 TRANS WAS BOILING HOT after bush hogging WHAT HAVE I DONE???

[ritcheyvs]

For those that don't know, DK models use a "wet" clutch stack to engage the PTO. If you have seen a motorcycle clutch pack or car auto transmission clutch stack, it's like that. The clutch is engaged by a hydraulic piston that gets a couple hundred psi from the power steering side of the hydraulic pump when the electrical PTO solenoid is powered. There are a couple different plumbing arrangements (reason I asked if it was a DK, DKs, or DKSE); one uses a modulator valve upstream of the PS circuit and the other uses a regulator downstream of the PS circuit. Clearly a lot of heat got dumped into the transmission, and probably not by conduction from the engine. The two likely ways to heat up that oil (and all that transmission metal) are deadheaded hydraulics and a slipping clutch. If that PTO clutch started slipping, a great deal of mechanical energy would become heat in the clutch pack which seems most likely considering the seals at the PTO clutch piston (and maybe others nearby) were destroyed. Also, once any of those seals leak substantially, the piston would lose pressure and allow even more slipping; a chain reaction. That's what I suspect happened here. But why? Was the clutch friction material contaminated with the wrong (old style) hydraulic fluid, which is not suitable for wet brakes or clutches? Were the clutch seals already compromised and leaky? Did the hydraulic system fail to provide sufficient pressure to the PTO clutch piston? Was the system simply overloaded? I guess we'll never know. But I'll never try to run a 3000 lb 8 ft mower behind my DK45s after reading this saga.

 

[ovrszd]

For those that don't know, DK models use a "wet" clutch stack to engage the PTO. If you have seen a motorcycle clutch pack or car auto transmission clutch stack, it's like that. The clutch is engaged by a hydraulic piston that gets a couple hundred psi from the power steering side of the hydraulic pump when the electrical PTO solenoid is powered. There are a couple different plumbing arrangements (reason I asked if it was a DK, DKs, or DKSE); one uses a modulator valve upstream of the PS circuit and the other uses a regulator downstream of the PS circuit. Clearly a lot of heat got dumped into the transmission, and probably not by conduction from the engine. The two likely ways to heat up that oil (and all that transmission metal) are deadheaded hydraulics and a slipping clutch. If that PTO clutch started slipping, a great deal of mechanical energy would become heat in the clutch pack which seems most likely considering the seals at the PTO clutch piston (and maybe others nearby) were destroyed. Also, once any of those seals leak substantially, the piston would lose pressure and allow even more slipping; a chain reaction. That's what I suspect happened here. But why? Was the clutch friction material contaminated with the wrong (old style) hydraulic fluid, which is not suitable for wet brakes or clutches? Were the clutch seals already compromised and leaky? Did the hydraulic system fail to provide sufficient pressure to the PTO clutch piston? Was the system simply overloaded? I guess we'll never know. But I'll never try to run a 3000 lb 8 ft mower behind my DK45s after reading this saga.

Good post. Thanks for the input!!!!

 

[DieselBound]

I'll second ovrszd's comment! Great post, ritcheyvs!

So, if I'm understanding this correctly, we're talking hydraulic fluid here. Should we expect there to be a cooler in this loop? Could there have been a clogged cooler? I know that lots of people overlook cleaning out their radiators fully (cleaning only the screens) and end up overheating. While the OP may not have overlooked something like this it's possible that the PO did (and compromised the system).

 

[Ford850]

I'll second ovrszd's comment! Great post, ritcheyvs!

So, if I'm understanding this correctly, we're talking hydraulic fluid here. Should we expect there to be a cooler in this loop? Could there have been a clogged cooler? I know that lots of people overlook cleaning out their radiators fully (cleaning only the screens) and end up overheating. While the OP may not have overlooked something like this it's possible that the PO did (and compromised the system).

The OP said Kioti doesn't put a fluid cooler on this model.

 

[DK35vince]

The OP said Kioti doesn't put a fluid cooler on this model.

The DK HST models have a cooler I believe. I don't think any DK gear models had a hydraulic cooler.

 

[rback33]

P.S. Soybeans.

I noticed right away it was beans. Helped my brother in-law finish a few weeks ago... my best "down time" is helping him farm.

 

[ovrszd]

I noticed right away it was beans. Helped my brother in-law finish a few weeks ago... my best "down time" is helping him farm.

Good for the Soul isn't it.

 

[quadmaster50]

For those that don't know, DK models use a "wet" clutch stack to engage the PTO. If you have seen a motorcycle clutch pack or car auto transmission clutch stack, it's like that. The clutch is engaged by a hydraulic piston that gets a couple hundred psi from the power steering side of the hydraulic pump when the electrical PTO solenoid is powered. There are a couple different plumbing arrangements (reason I asked if it was a DK, DKs, or DKSE); one uses a modulator valve upstream of the PS circuit and the other uses a regulator downstream of the PS circuit. Clearly a lot of heat got dumped into the transmission, and probably not by conduction from the engine. The two likely ways to heat up that oil (and all that transmission metal) are deadheaded hydraulics and a slipping clutch. If that PTO clutch started slipping, a great deal of mechanical energy would become heat in the clutch pack which seems most likely considering the seals at the PTO clutch piston (and maybe others nearby) were destroyed. Also, once any of those seals leak substantially, the piston would lose pressure and allow even more slipping; a chain reaction. That's what I suspect happened here. But why? Was the clutch friction material contaminated with the wrong (old style) hydraulic fluid, which is not suitable for wet brakes or clutches? Were the clutch seals already compromised and leaky? Did the hydraulic system fail to provide sufficient pressure to the PTO clutch piston? Was the system simply overloaded? I guess we'll never know. But I'll never try to run a 3000 lb 8 ft mower behind my DK45s after reading this saga.

Thanks for that, yes the tractor had near 600 hours when it got it, same as new, from the original owner that only used it for tinkering around the house. Never even mowed with it, It still had the factory PTO cap on the pto. It was completely serviced at 500 hours by a Kioti dealer in Indiana right before i got it at 57X hours..
The clutch was not slipping a bit when i shut it off, for sure no doubts about it... I would hit dirt and it would kill the engine instantly nearly...
I have indeed let a local dealer take it, They fixed it and sent it on its way to someone else, i have no idea who but i feel sorry for them

Good news is I've put 300 hours on my john deere with the same mower and a 17' bat wing! going good!
Thanks guys!

 

[NC419N]

300 hours in a little over a month?? Thats a lot of mowing
What size Deere did you replace it with

 

[quadmaster50]

300 hours in a little over a month?? Thats a lot of mowing
What size Deere did you replace it with

Well not quite 300, It was used with 65XX hours on it( yes 6500, runs same as new) so i think I've put like 280 on it. Its a 200? john deere 5410 MFWD I used it for hire and have been working 10 hour days 5-6 days a week wile i have light and is not zero deg haha.