X500 - K72B Transmission (slow in forward drive when hot)

[Jackson53]

Greetings all,

My X500 has the Kanzaki K72B transmission and when the transmission oil gets hot after approx one hour of lawn mowing there is a noticeable loss of power in forward drive. The X500 has done 200 hours and is still under warranty but would like to know if anyone has had similar problem.
The engine is running smoothly, no unusual noises from any of the rotating equipment (gearbox, idlers, pulleys, etc), traction and mower deck drive belts are taut and not slipping, gearbox and engine oil all at correct levels (no signs of any leaks).
Removed the mower deck and inspected the mower drive belt and traction drive belt - both belts in excellent condition (no cracks) and no slackness.
Suspect centre case and hydro motor in transmission might be the problem. Appreciate any feedback.

 

[tomplum]

Have you changed the hydraulic oil yet? They like to see an initial change @ 50 hours and every 200 hours. It is also a good practice to ensure that the transaxle is kept clean.

 

[crazyal]

What sort of temperatures do you see (both weather and oil)? I haven't noticed any loss of power and I often mow up to 3 hours on my hilly yard. But the temps haven't been too hot here, maybe low to mid 80s(°f) or less. Is there any grass on top of the transmission? Does the fan have all it's blades? Tuff Torq recommends not going above 90°C. If you don't have one I would get one of those cheap infrared temperature gun. When it starts to loose power check the temp in a number of spots. If you're careful and have the means I would check the oil temp in the plastic tank as well. If it doesn't have it I would get full synthetic oil in it as well. I don't think I've heard of people having problems with the K72, hopefully it's something simple.

 

[Richard001]

Welcome to TBN.

Richard

 

[rekees4300]

The X500 has done 200 hours and is still under warranty but would like to know if anyone has had similar problem.

Have had my X500 since 2012 (125 hours) and haven't had any loss of power problems. That transmission has a good reputation. Since your X500 is still under warranty, I'd take it to the JD dealer and let him figure it out.

 

[Jackson53]

Yes - changed transmission oil at 50 hours and X500 currently has just over 200 hours. Next transmission oil change is 250 hours. Transmission is clean including fan.

 

[Jackson53]

Have had my X500 since 2012 (125 hours) and haven't had any loss of power problems. That transmission has a good reputation. Since your X500 is still under warranty, I'd take it to the JD dealer and let him figure it out.

Yes still under warranty and the JD dealer has looked at the transmission, adjusted linkages and advised everything okay. After approx. (1) hour mowing lawns (mainly level and couple of gentle slopes) and the transmission oil gets hot there is a loss of power. The X500 is going back to the dealer.

 

[Jackson53]

Welcome to TBN.

Richard

Thanks Richard

 

[Jackson53]

What sort of temperatures do you see (both weather and oil)? I haven't noticed any loss of power and I often mow up to 3 hours on my hilly yard. But the temps haven't been too hot here, maybe low to mid 80s(ｰf) or less. Is there any grass on top of the transmission? Does the fan have all it's blades? Tuff Torq recommends not going above 90ｰC. If you don't have one I would get one of those cheap infrared temperature gun. When it starts to loose power check the temp in a number of spots. If you're careful and have the means I would check the oil temp in the plastic tank as well. If it doesn't have it I would get full synthetic oil in it as well. I don't think I've heard of people having problems with the K72, hopefully it's something simple.

The temperature ranges are between 8C-22C in winter and 18C-32C in summer. Using JD JDM20C HY-GARD - so no problems from correct oil perspective.

 

[Spanner]

+1 on the question of Trans Oil Replacement on schedule?
The dealer doesn't have to do that. It's acceptable for you to DIY as long as you use the Lo-Viz Hygard and keep the receipt and record the event in your Owners Manual, Service Record section. (Which I'm sure you did.)

The dealer is probably unwilling to commit a staff member for an hour to run the machine up to temperature so as to replicate the fault as JD won't cover that time under the warranty.
Their test will be what is called a "Slope Test" where the machine should hold it's position on a 30-40 degree slope with light pedal pressure. Since they normally do this test when the unit is cold it usually fails to fail the test. (i.e. It passes). Then the disputes begin...

IF not too far from the dealer, can you ask for a Field Service Tech to call at a pre-arranged time so you can run it for an hour beforehand so they can experience the loss of power? Then they will file a DTAC report. Then you get a new Trans.

Also ask if your dealer has a Tech called Aaron and if so, let me know.

Also, check the tension spring on the belt idler tension plate and that the plate is moving freely to ensure correct tension. (I know you say they're taut. Just double check) I found the X500 Trans Belt Idlers to be a weak point. They are a warranty replacement if rough/noisy.

The remedy for a weak transmission is full warranty replacement.

This warranty support is one good reason why you bought a JD!