955l 13x trouble shoot torque converter

Oldcase125b · Jan 24, 2020

Brand new to posting on forum but have been reading for a while. Thank you all for the good information. Bought a cat 955l serial number 13x got service manuals to diagnose torque converter and transmission overheating after about 30 minutes of running. Pressure also drops, shifter will return to neutral.

Nige · Jan 25, 2020

Which pressure is dropping and where exactly are you measuring it.?
Do you have any idea of what type/viscosity of fluid is in the power train.?

DMiller · Jan 25, 2020

Nige is the Cooler for these as the D6C Series as a Side mount to the radiator? Choked possibly if is?

Old Magnet · Jan 26, 2020

Trans/torque oil is air cooled as stated.

Oldcase125b · Jan 27, 2020

Nige, thank you for your response. I am rigging up a better gauge to test my torque converter outlet pressure. Had checked pressure before directly from port on top of pump. Got reading of 300psi, but gauge range goes to 5,000 psi. Changed transmission fluid, filter and replaced with rotella 30 w. Have also cleaned transmission magnets. Cleaned small suction screen on top of steering housing. Replaced transmission pump seal to make sure fluid was not leaking past.

Oldcase125b · Jan 27, 2020

Oldcase125b · Jan 27, 2020

Nige, early on in troubleshooting process I removed transmission control valve pack and found one bad oring out of the six that were there. Didn't seem to fix issue.

Oldcase125b · Jan 27, 2020

Control valve

Oldcase125b · Jan 27, 2020

O-ring was chewed up

Nige · Jan 27, 2020

Oldcase125b said:
Changed transmission fluid, filter and replaced with rotella 30 w.

That's an engine oil if I'm not mistaken. If I am correct then I'd think twice about using that oil in powershift transmission clutches. You really need something the meets TO-4 specification (It was TO-2 back in the day not but most oils today meet TO-4)

Welder Dave · Jan 27, 2020

That screen looks to have a bunch of metal filings in it.

DMiller · Jan 27, 2020

Has a bunch of something on it.

John C. · Jan 28, 2020

The material on that strainer is pretty normal for an old steering clutch machine. As far as heating problems with the converter go, I would suggest you get an infrared thermometer to find where the heat is coming from. The usual suspects are the cooler and excessive clearances in the torque converter. You can check the inlet and outlet temps on the fittings of the hoses going into and out of the cooler. You can check temperatures on the inlet and outlet valves on the torque converter. In my experiences with old Cat dozers, the converters are the usual problems. If you remove the converter for repair you will need to remove the cooler as well and have it cleaned and checked for leaks.

Oldcase125b · Jan 29, 2020

Thanks for all input, I got a new 600psi gauge and hose to test pressures. Oil cooler was warm at bottom and cool at top after running and pushing a little dirt. I have installed new oil cooler bypass valve and temp gauge for torque converter.

Nige · Feb 1, 2020

The attached may help you when you get round to testing.

digginjake · Feb 11, 2020

Thanks nige, my email got messed up, digginjake is old username. I put new 600psi gauge on transmission filter test port. Reading is about 310 psi, but needle is jumping all over, always have to add about a gallon of oil to get reading up to 300psi. After about 30 minutes of running pressure drops to around 100psi, will fluctuate back up to 250psi. Going to check converter outlet pressure next.

digginjake · Feb 11, 2020

Found used torque converter, ordered new seals and bearings.

digginjake · Feb 11, 2020

John C. · Feb 11, 2020

I can't tell for sure but the left side of what I think is the stator seems to have a lip showing on the radial surface. If it is, you got problems.

digginjake · Feb 11, 2020

John c, I will take a closer look tomorrow and get better picture thanks.

955l 13x trouble shoot torque converter

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