CK2610 HST Hydraulic issues

[Deadarmor2]

2018 CK2610 436 hours
Just changed Hydraulic fluid/filters, oil change, fuel filter
Issues started before changing Hydraulic fluid/filters.
Issues occur when tractor is fully warmed up and worse after using it for a bit
No remote hydro's
I am mechanically inclined.

1)At idle, not moving, if I roll the bucket or raise the boom and hold it for a couple seconds, RPM drops by 3000 RPM from 12 to 9. When I first got the tractor it barely blinked while doing the same thing.

2)While driving forward in M at 2500 RPM, 4x4 or 4x2 engaged, it will erratically start stalling. Mostly when turning the steering wheel while moving forward, flat ground. Going up a slight hill it will start to stall on top of the hill or when cresting the slight hill.

3)While driving forward in M, 4x2 or 4x4, 2500 RPM, if you raise the bucket or boom, while moving, RPM's will also drop substantially.

Never had any of these issues when I first bought it. These issues started around 390 hours. Had it in to dealership here, they couldn't find anything. I know they did not pressure test the Hydro's like I asked, but they said it didn't act up while there. I don't trust them though. It was stalling out worse, changed the fuel filter, and about 90% of the issues went away. Just residual hydro issues I think. I have been checking hoses everything looks good. Fluid return to the trans looks good. Starting to think the secondary pump seals are toast because the secondary goes to the steering and then recharges the HST. Anyone else have these issues? Could a stuck relief valve or stuck main relief valve be an issue? I am in a dusty desert type environment. Cleaned my loader lines yesterday and there was some dirt that managed to seep down between the connections. Anyways, looking for any thoughts on these issues.
Thanks

 

[loggin]

2018 CK2610 436 hours
Just changed Hydraulic fluid/filters, oil change, fuel filter
Issues started before changing Hydraulic fluid/filters.
Issues occur when tractor is fully warmed up and worse after using it for a bit
No remote hydro's
I am mechanically inclined.

1)At idle, not moving, if I roll the bucket or raise the boom and hold it for a couple seconds, RPM drops by 3000 RPM from 12 to 9. When I first got the tractor it barely blinked while doing the same thing.

2)While driving forward in M at 2500 RPM, 4x4 or 4x2 engaged, it will erratically start stalling. Mostly when turning the steering wheel while moving forward, flat ground. Going up a slight hill it will start to stall on top of the hill or when cresting the slight hill.

3)While driving forward in M, 4x2 or 4x4, 2500 RPM, if you raise the bucket or boom, while moving, RPM's will also drop substantially.

Never had any of these issues when I first bought it. These issues started around 390 hours. Had it in to dealership here, they couldn't find anything. I know they did not pressure test the Hydro's like I asked, but they said it didn't act up while there. I don't trust them though. It was stalling out worse, changed the fuel filter, and about 90% of the issues went away. Just residual hydro issues I think. I have been checking hoses everything looks good. Fluid return to the trans looks good. Starting to think the secondary pump seals are toast because the secondary goes to the steering and then recharges the HST. Anyone else have these issues? Could a stuck relief valve or stuck main relief valve be an issue? I am in a dusty desert type environment. Cleaned my loader lines yesterday and there was some dirt that managed to seep down between the connections. Anyways, looking for any thoughts on these issues.
Thanks

I don't have much experience with the electronics on these newer tractors but from what you have said it may not be the hydraulics. Older engines have mechanical governors that increase fuel when there is a load put on the engine. I believe newer (tier 4) engines use electronics to govern. Might be a sensor?

Also might be a fuel issue. You mentioned it got better after you changed the fuel filter. Did you notice any water or contaminants in the filter bowl?

Sorry I can't be of more help. Perhaps someone else who knows your machine better can chime in here.

 

[Deadarmor2]

Appreciate the reply. I should have added that I do have the workshop manual. I have checked the applicable sensors and they all check it out. Diesel was very Orange when I changed it, I blew out all the fuel lines in the process and cleaned out the bowl. I did not find an abnormal amount of water, nor did I find any contaminants so to speak. I also completed a compression test today and everything is in order there. It seems confined to the hydro's.
thanks