CAT 24M grader torque convertor overheating

[Machinedoctor]

Hi,
Just after some ideas and where to head next. Machine background: transmission oil level is correct, t/c inlet pressure and outlet pressure and lock up clutch pressure is within specifications. Transmission modulation pressures are within specifications. Engine coolant level is correct. Did a stall test and the temperature of oil line coming out of t/c is starts at 70 degrees Celsius and rapidly climbs to above 130 degrees Celsius. When the stall condition is removed and engine is free- revved to cool temperature down it drops quite quickly. Seems to be a max of 30 degree celcius max temperature drop across the powertrain oil cooler. T/c is at 59% life. Dont have any oil sampling results.
Thanks in advance.

 

[Mark250]

hi serial number please.
did the problem happen slowly or suddenly or after service or repair?
Have you checked the screens? Have you a history of SOS?
when you did the stall test did you record the engine speed and checked against spec? did you check for drive shaft rotation while stalled?
the free wheeling stators had issues with the springs failing and were upgraded
parts of the springs are sometimes found in the strainers and by checking stall speeds
Also I would be installing the latest software because the lockup clutch strategy has changed over time
Have you confirmed the temp sensors are correct? have tried calibrating the transmission?
Mark

 

[Machinedoctor]

hi serial number please.
did the problem happen slowly or suddenly or after service or repair?
Have you checked the screens? Have you a history of SOS?
when you did the stall test did you record the engine speed and checked against spec? did you check for drive shaft rotation while stalled?
the free wheeling stators had issues with the springs failing and were upgraded
parts of the springs are sometimes found in the strainers and by checking stall speeds
Also I would be installing the latest software because the lockup clutch strategy has changed over time
Have you confirmed the temp sensors are correct? have tried calibrating the transmission?
Mark

Hi Mark,
Off hand i think it was B9K00325. Apparently it was having transmission shifting problems. Screens and filters were checked. Some metal fragments were found in them. Now, the shifting problem has gone away and the torque convertor is overheating. I was not alerted to any trends from SOS reports. There is still very fine fragments in the filter base, when you remove the filter. Yes, the stall speed was checked against spec- all good there. No, i did not check for drive shaft rotation while stalled. On the day i was tasked to continue on with diagnosis, a CAT auto electrician upgraded the software. Yes the temp sensors were correct. Confirmed by looking at E.T and using a temp gun. No did not try calibrating the transmission. I am off shift now, so i will be checking in to see how they went with it. Thanks for your input Mark, appreciated.
Mick

 

[Mark250]

fine metal in filer generally indicates pump failure. some of the early machines did not have the magnet fitted
here is some reading hope it helps
don't forget to check trans lube pressure, as low pressure could indicate flow problems through the convertor, (pump) or a large internal leak could cause similar issues
Mark

 

[Machinedoctor]

Thanks Mark, will let you know of the outcome.

 

[Mark250]

ok

 

[Machinedoctor]

Hi Mark,
Well i have not been back to that grader. I have been told that what failed was the transmission. I am a bit confused as to why, because all the tests i had done did not point to it. I must have missed something. Anyways, i will be triple checking results next time and even verifying with someone else and making sure gauge is showing the correct figures against another one!
Thanks for your help.
Michael

 

[Mark250]

don't forget to check trans lube pressure, as low pressure could indicate flow problems through the convertor, (pump) or a large internal leak could cause similar issues
Mark

I always check lube pressure as I said above it is always a good indicator of flow problems or internal leakage
Mark