Cat IT28B. No movment forward or reveres

Hello! I have a 1990 Cat IT28B with 22,000 hours (serial number: 5SD00953). It won't drive on any gear, neither forward nor reverse. Before this issue occurred, the machine operated fine. I did notice that when shifting from gear 2 to gear 3, there was a slight hesitation—the shift felt like it "lagged a bit," though it eventually engaged. When manually moving the gear or speed spool, I could feel some resistance shifting from gear 2 to gear 3, although I'm unsure whether this resistance is from the transmission control unit itself or the pneumatic cylinder moving the spool). The loader is equipped with an automatic transmission (electric and pneumatic). I've performed troubleshooting and confirmed that the shift levers (speed and direction) on the transmission move correctly. I noticed a lack of pressure at the test port on the oil filter, so I cleaned the suction screen, replaced the filter, and changed the oil. However, there's still no pressure at the test port. The transmission filter looked clogged, with black particles and black oil. The oil itself was black, and I found black particles (similar to clutch disc material), up to the size of a thumbnail, in the suction screen—no metal fragments though. The magnets had a sludge with fine metal particles. What should be the next step in troubleshooting? Should I replace the seals on the suction hose, or go directly to changing the oil pump? Or is there something else I should investigate first? Thanks in advance! Best Regards Fredrik

account.account@protonmai said: I noticed a lack of pressure at the test port on the oil filter, so I cleaned the suction screen, replaced the filter, and changed the oil. However, there's still no pressure at the test port. What should be the next step in troubleshooting? Should I replace the seals on the suction hose, or go directly to changing the oil pump? Or is there something else I should investigate first? Click to expand... I would suggest to maybe try to kill two birds with one stone. Remove the suction line and the pump. It is a relatively simple process - procedure attached. Take a look inside the pump for any indication of wear or that something is broken. Also check that nothing is broken in the gear set that drives the pump. If you find nothing reassemble the pump with new seals. Reinstall the pump and suction line with new O-Rings and see what pressure you have at the test point. Based on the amount of clutch material you found in the suction screen a transmission rebuild may well be in your future in addition to the problems of lack of pressure.

Thank you for your response, I will remove the pump and inspect it. Will report back. I have attached some pictures of the material in the screen and oil plug.

The quantity of material shown in your photos may or may not be serious depending on how much time has passed since the screen assembly was previously removed.

Maybe I should add that nothing seems to be broken in the gear set driving the pump (maybe I have this wrong) because the hydraulics (loader and steering) works.

account.account@protonmai said: Maybe I should add that nothing seems to be broken in the gear set driving the pump (maybe I have this wrong) because the hydraulics (loader and steering) works. Click to expand... The pump for the transmission is a separate item to the pump for implements & steering.

Nige said: The quantity of material shown in your photos may or may not be serious depending on how much time has passed since the screen assembly was previously removed. Click to expand... I have had the machine a couple of months and the history is unknown to me. But I would say that it was probably way over the recommended interval. What I did noticed was that the old filter type: 2P-5834 was not installed, but the new type: 1R-0746 was installed (the one with a spiral on the outside). So a guess would be that the material has been in there since the filter type was replaced, but I don't know when the new filter replece the old one.

Nige said: The pump for the transmission is a separate item to the pump for implements & steering. Click to expand... Got it. My bad, I though used the same shaft going through the transmission pump which is closest to the transmission.

account.account@protonmai said: What I did noticed was that the old filter type: 2P-5834 was not installed, but the new type: 1R-0746 was installed (the one with a spiral on the outside). So a guess would be that the material has been in there since the filter type was replaced, but I don't know when the new filter replece the old one. Click to expand... According to the system 2P-5834 filter element is cancelled and replaced by 1R-0746.

Starting to sound like maybe a plugged screened orifice in the trans control valve.

Mobiltech said: Starting to sound like maybe a plugged screened orifice in the trans control valve. Click to expand... Highly possible with the amount of contamination that has been circulating.

Mobiltech said: Starting to sound like maybe a plugged screened orifice in the trans control valve. Click to expand... Hi! Thanks for your response, would that also cause no oil pressure at the oil filter?

This is a how the filter look like. Maybe the bypass had opened?

account.account@protonmai said: This is a how the filter look like. Maybe the bypass had opened? Click to expand... What was the outcome? I’m having the exact same issues.