Mustang 310 skid noise when turning

[pcrmerln]

Have a new to me mustang 310 skid w the kohler 321 motor. Got the motor running fine now and hydraulics all work well. When driving straight forward or back, no problem. If I engage just one side or try to turn in place it bogs down really hard, makes a loud noise somewhere deepr then a whine and won't do it. It doesn't sound quite like a grind or chatter/vibration. More like a whine but not high pitch. More growl.
Hydrostat pumps? Or more likely hydraulic motor? Any way to test? Anyone know cross reference for parts? I have a manual but searching for the parts doesn't turn up anything. Or if I can rebuild them or something.
I changed all the fluid and put in the Dexron fluid recommended and all 3 new filters.
Any help or suggestions appreciated.

 

[Firefighter]

are the hydros belt driven on that unit, could be a belt slip causing a turning fault

 

[pcrmerln]

are the hydros belt driven on that unit, could be a belt slip causing a turning fault

Interesting thought. They are belt driven. I hadn't thought about changing the belt but that is a much cheaper and easier fix than pumps or motors.... thanks for the idea

 

[haymaker]

Interesting thought. They are belt driven. I hadn't thought about changing the belt but that is a much cheaper and easier fix than pumps or motors.... thanks for the idea

A 5 dollar can of belt dressing to give the belt some extra grip might help to confirm or elevate the problem temporarily also.

 

[pcrmerln]

are the hydros belt driven on that unit, could be a belt slip causing a turning fault

Interesting thought. They are belt driven. I hadn't thought about changing the belt but that is a much cheaper and easier fix than pumps or motors.... thanks for the idea

 

[pcrmerln]

are the hydros belt driven on that unit, could be a belt slip causing a turning fault

Interesting thought. They are belt driven. I hadn't thought about changing the belt but that is a much cheaper and easier fix than pumps or motors.... thanks for the idea

 

[pcrmerln]

I am away for work for a week but will try out those ideas when I get back. Has anyone found a source for parts like the hydrostatic pump or hydraulic motor? Or are those able to be rebuilt since they are so old.

 

[haymaker]

I am away for work for a week but will try out those ideas when I get back. Has anyone found a source for parts like the hydrostatic pump or hydraulic motor? Or are those able to be rebuilt since they are so old.

River Fluid Power might be the guy to ask. He has helped out many here with pumps.

 

[pcrmerln]

Did the belt dressing and noticed it a little better so ordered a belt. Got that on this morning and it did noticeably drive better and less noise however it did point out the problem more. The right handle/motor is the problem. Making right turns using only the left handle seems to work well with minimal noise. Making left turns however brings back the noise I mentioned.
I will try to get video w sound so maybe it will help to figure out if it's a pump or motor. I feel like it is the motor but that's more a gut feel since I have never really worked on one of these before.