Looking for some help with our new to us 246 cat. 4xxx hours Something is off with the hydrostatic drive system. It seems weak going forward and turning but not in reverse. I know the piston pump pilots are ran off the gear pump which also runs the loader but I have plenty of strength in the loader. Anyone seen anything like this before? Also can anyone give me some kind of idea how strong the drives should be?Thanks.
My first thought here would be to check pilot pressure and then run it and see if it drops when you think it is weak. And go from there. If it's good one way the pumps and motors are probably ok.
If you want technical information such as pressure specs, etc, you'll need to post a Serial Number. Getting on for 20 different models of 246.
It’s sn 5sz86126. I believe that’s the newest break before switching to B series
Are you sure it's not 5SZ06126.? The number you gave does not exist in the system.
That is very likley I thought it was a 8 but it could be a 0 with a line through it.
Here’s a pic of the sn. I had bought a digital service manual but it doesn’t match the machine I guess it’s the wrong s/n range
Yep, it’s a zero. You didn’t buy one of those $65 digital manuals out of Lithuania did you.? A kosher factory service manual is priced at over $1000, or are you talking about an Operation & Maintenance Manual.?
Yea no it’s a operations manual. It’s no big deal most things are close enough that I learned a lot from it. Can you provide me some instructions on where I should be looking. I have some hydraulic gauges and extra lines but I need to get the quick coupler to be able to hook onto any of the service ports.
The correct Operation & Maintenance Manual for 5SZ06126 is Cat Publication SEBU7468. I can't see a used one anywhere at this time but a pdf copy of the latest version of that manual can be downloaded from Cat for $52. Attached is the procedure to test pilot pressure as suggested above by @Tyler d4c .
That's a good start. I'd want to rule out the pilot control valve (joystick) first. Is it leaking? Any cavitation noises coming from it?
I have more of a feeling that the forward servo in the pump maybe leaking internally
I’m waiting on a fitting to come in to hook onto the service ports so we can see what’s going on supposed to be here Friday I’ll report back with some findings then I hope.
The pilot control is leaking a bit and definitely needs to be resealed but it’s not making any unfriendly noises.
There will also be a line relief/charge valve on each drive pump for each direction. If one or both for forward are not holding it could cause a charge pressure drop. Check stall pressure in forward and reverse on each drive pump. Is it slow in forward or just lacking power?
I was planning on waiting to see what pilot pressures looked like before posting the procedures for testing the line relief valves and the hydrostatic drive system.
According to phone gps it runs between 5-6 mph forward and 6-7 in reverse.
Well tonight I followed my gut and took apart the charge pump as I’ve resealed many gear style pumps before at work and I’m pretty sure I’ve found the problem. The e seals were completely shot and have been for some time as the seal pockets have been eroded by bypassing fluid. The rest of the pump looks ok other than minor wear on the pump walls. I went ahead and cut open the hydraulic filter and i found no metallics in it so I’m hoping a new pump will have me back in order. I’m not going to bother with even trying to reseal this pump imo if it will even hold it will be a time bomb.
Good find, but it doesn't explain why it's slow in reverse. Interested to know how it goes when you get it back together.
If the problen still is not resolved when you get the gear pump sorted out the procedures for the line relief valves and testing the hydrostat system are ready and waiting for you.
Thanks for the help.