B200 Hydrostatic Issues - sluggish/no movement forward or back when warm.

   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm.
  • Thread Starter
#11  
Dennis,

thanks for the reply - even on a holiday like today!

I did loosen the charge adjusting screw a bit while running and did not see any oil leak...I may try to crank the engine with the plug removed to see if any oil comes out. If nothing comes out, could this indicate there is some internal blockage internally?

I was going to cap off the drive motor after I did the adjustments, as no one seemed to have the M26-1.5 caps or anything can cap it off for short money. I will go this route to see if I can determine where the problem is, as capping off the pump is simpler. Either case it looks like it will be lots of money as drive motor is ~$1800 and hydrostatic pump is a lot more...and neither are readily available.

I just want to make sure I am not doing something stupid and overlooking something. I will go through the procedure a few more times, and really make sure I have the pressure gauges in the right locations...as there are many test ports/plugs on the pump and the pictures in the manuals are not 100% clear.

Another question for you:

You said the pressure when the motor is capped off should be 3600PSI. Where is this measured, on the Charge port or at the output from the pump to the motor...or are they internally connected anyway?

Thanks again for all your help.
 
   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm. #12  
Dennis,

thanks for the reply - even on a holiday like today!

I did loosen the charge adjusting screw a bit while running and did not see any oil leak...I may try to crank the engine with the plug removed to see if any oil comes out. If nothing comes out, could this indicate there is some internal blockage internally?

I was going to cap off the drive motor after I did the adjustments, as no one seemed to have the M26-1.5 caps or anything can cap it off for short money. I will go this route to see if I can determine where the problem is, as capping off the pump is simpler. Either case it looks like it will be lots of money as drive motor is ~$1800 and hydrostatic pump is a lot more...and neither are readily available.

I just want to make sure I am not doing something stupid and overlooking something. I will go through the procedure a few more times, and really make sure I have the pressure gauges in the right locations...as there are many test ports/plugs on the pump and the pictures in the manuals are not 100% clear.

Another question for you:

You said the pressure when the motor is capped off should be 3600PSI. Where is this measured, on the Charge port or at the output from the pump to the motor...or are they internally connected anyway?

Thanks again for all your help.

Whether oil comes out the adjusting screw or is not important, just depends on how the drain off from the relief is ported/directed.
The 3600 psi is drive pressure relief, put gauge in pump drive pressure test port or make a fitting for the gauge into the plug plugging off the pump outlet.
 
   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm.
  • Thread Starter
#13  
Dennis

I have capped the pump and get the following readings:

The charge pressure is 80PSI at 1000RPM and 110PSI at 3000RPM. Nothing I do can get the charge pressure close to the spec of 320PSI. Once the oil heats up charge pressure is close to zero all the time.

Pump Pressure and Charge Forward Travel Port Pressure at MAX RPM (~3000)
(at 1000 RPM I get close to zero readings).

Cold, on start-up:
2200PSI at pump output
2600PSI at Forward Travel Test Port

At 145F
1000PSi at pump output
1300PSI at Forward Travel Test Port

I have the charge pressure adjustment all the way in as this produced the best output pressure, though adjusting the charge pressure did not affect the output pressure much at all.

From all that you have said, it seems the pump is gone and/or has internal leaking/bypass.
Before I take it out and attempt to get it rebuilt, is there any other adjustment, bypass or relief valve internal or external to the pump that could have such an affect on the output pressure? If so I can try to cap/adjust/remove these potential loss of pressure sources.

I just wanted to check to ensure I am not missing some other adjustment or bypass. I would hate to pull the pump, tear it down and not have any indication of wear or damage. The machine only has about 650 hrs and the fluid & filter was changed at 500 hrs and is very clean and no debris in the filter, hence I really think contamination of the hyd oil is not the cause. It is just strange that it would fail with such low hours. The tractor has sat for long times and perhaps some of the internal seals dried out.

Thanks again for all your help - it looks like this is probably going to be a lot longer and expensive than I was hoping.
Bobcat has a replacement pump in the USA, but it is $5K! Worst case I will have to go that route, but only once I know it is not something like a bypass valve and that this pump cannot be repaired.

Thanks for all your help so far, Greg
 
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   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm. #14  
If it will maintain charge pressure with pump capped off, do the flushing spool test (test #2 in the manual) if that holds or can be adjusted to hold the 30 lb. differential in charge then proceed to the Torque Limiter adjustment.

If the Flushing Spool dumps too much oil when pump starts to come on stroke, it dumps too much oil causing excessive loss of charge pressure and lower max drive pressure.
 
   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm.
  • Thread Starter
#15  
Dennis,

thanks again for your reply.

I will do the test #2 - but my issue is that is does not maintain charge pressure with the pump capped off. The max charge pressure I can get is 200 PSI, when cold and at max RPM (3000), with the adjuster all the way closed.

I can only get some pressure at the drive cap or on the charge plate at max RPM (3000). At 1000 RPM (where the tests are supposed to be run) I get basically zero pressure. I will do all the tests again, starting with #2, but I fear that unless there is some internal or external bypass or relief valve that has failed, it is the pump mechanism itself that has failed as it is not able to keep the pressure required to even meet minimum specs.

Any other suggestions are appreciated, and I thank you for your time.
If this would be quicker, I am happy to post my number or email and we can talk on the phone and I will stop taking all your time.

Thanks again, Greg
 
   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm. #16  
Dennis,

thanks again for your reply.

I will do the test #2 - but my issue is that is does not maintain charge pressure with the pump capped off. The max charge pressure I can get is 200 PSI, when cold and at max RPM (3000), with the adjuster all the way closed.

I can only get some pressure at the drive cap or on the charge plate at max RPM (3000). At 1000 RPM (where the tests are supposed to be run) I get basically zero pressure. I will do all the tests again, starting with #2, but I fear that unless there is some internal or external bypass or relief valve that has failed, it is the pump mechanism itself that has failed as it is not able to keep the pressure required to even meet minimum specs.

Any other suggestions are appreciated, and I thank you for your time.
If this would be quicker, I am happy to post my number or email and we can talk on the phone and I will stop taking all your time.

Thanks again, Greg

Greg, You're probably right, but what I would do is try shutting the Flushing Valve down to zero and see if charge pressure comes back. If it does then loss of oil is going across the Flushing Valve. Again, been number of years since I adjusted one of these but I think the Flushing Valve is very much like the Charge Pressure Relief, just a poppet with adjustable spring pushing on it.
 
   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm.
  • Thread Starter
#17  
Dennis,

thanks again.

I tried all options, i.e. flushing valve fully open and fully closed, charge port fully open and fully closed.

The adjustments in either direction have little or no difference in pressure on the charge port or the forward drive test port.

The only time I get close to anything as operational pressure is when the system is cold and I rev it to max RPM (3000).
The tests are supposed to be done at 1000 RPM, and at that speed I get all zeros or close to it.

Also note the charge port adjustment makes no difference, i.e. all the way in (closed) or out does not affect the charge pressure readings at all.

The final set of tests results are (with output of pump capped and charge pressure adjustment fully closed (IN)):

Flushing Valve IN all the way (closed)
RPM Forward Test Port Pressure Charge Port Pressure
1000 2200 80 with change in pressure for test #2 is 10 PSI
3000 2600 110 with change in pressure for test #2 is 15 PSI

Flushing Valve OUT all the way (open)
RPM Forward Test Port Pressure Charge Port Pressure
1000 1500 80 with change in pressure for test #2 is 20 PSI
3000 1900 110 with change in pressure for test #2 is 38 PSI

I should also say that I tried the Torque adjustment in different positions and this does have some affect on max pressure of the output, but only decreased its max output from 2600 to something lower in the range of 2000PSI and this is at max RPM and the oil being room temp.

Once the oil heats up to 120-140 all the pressures drop to almost nothing.

My gut feel is the pump has some internal leaking and I am preparing to pull it out (unless you have some last minute ideas) and take it to a shop and see if they can find some internal reason it is not working, i.e. seals or scores or something broken.

Any last minute suggestions? Greatly appreciate your help in all this mess.

Sincerely, Greg
 
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   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm. #18  
Guess it is time to take a look inside the pump..
 
   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm. #19  
Dennis,

thanks again.

I tried all options, i.e. flushing valve fully open and fully closed, charge port fully open and fully closed.

The adjustments in either direction have little or no difference in pressure on the charge port or the forward drive test port.

The only time I get close to anything as operational pressure is when the system is cold and I rev it to max RPM (3000).
The tests are supposed to be done at 1000 RPM, and at that speed I get all zeros or close to it.

Also note the charge port adjustment makes no difference, i.e. all the way in (closed) or out does not affect the charge pressure readings at all.

The final set of tests results are (with output of pump capped and charge pressure adjustment fully closed (IN)):

Flushing Valve IN all the way (closed)
RPM Forward Test Port Pressure Charge Port Pressure
1000 2200 80 with change in pressure for test #2 is 10 PSI
3000 2600 110 with change in pressure for test #2 is 15 PSI

Flushing Valve OUT all the way (open)
RPM Forward Test Port Pressure Charge Port Pressure
1000 1500 80 with change in pressure for test #2 is 20 PSI
3000 1900 110 with change in pressure for test #2 is 38 PSI

I should also say that I tried the Torque adjustment in different positions and this does have some affect on max pressure of the output, but only decreased its max output from 2600 to something lower in the range of 2000PSI and this is at max RPM and the oil being room temp.

Once the oil heats up to 120-140 all the pressures drop to almost nothing.

My gut feel is the pump has some internal leaking and I am preparing to pull it out (unless you have some last minute ideas) and take it to a shop and see if they can find some internal reason it is not working, i.e. seals or scores or something broken.

Any last minute suggestions? Greatly appreciate your help in all this mess.

Sincerely, Greg

Hi Greg, I was reading your thread an wondering if you were able to straighten it out. I'm battling the same thing right now. I'm at the point where I'm trying to pull the Parker drive motor and can't seem to get it all the way you. It seems there might be a nut on the end of the shaft. So just scouring the internet for information. Thanks
 
   / B200 Hydrostatic Issues - sluggish/no movement forward or back when warm.
  • Thread Starter
#20  
I am happy to help. What problem are you trying to solve?

If it is forward movement, then I suspect it is the hydrostatic pump as this was my issue and since my post I have been contacted by a few people with the same issue. Seems these B200 the pumps are too small and wear out in less than 1000 hours. I can expound on this if you think this may be the issue. I fixed mine and did some retro-fitting to help prevent this in the future. Simple check if the pump is working is to cap the output ports and the tractor should stall out if you actuate the forward/reverse direction.

If you are trying to get the parker drive motor out, I cannot help, as I was never able to get mine out. It turned out this was not the problem anyway, so I left it alone. It would seem there is a nut or clip or similar on the shaft keeping it in there, but short of breaking down the transfer case, I am not sure how one would get to such a clip. All the diagrams and advice I have gotten says there is no clip and it should just come out, but I could not get it out, ever! I was able to get the drive motor to move in the housing by removing all the bolts, but could never get it out or even loose. My point is that it is not bound or rusted in on the housing, there is something else holding it in there.


"Hi Greg, I was reading your thread an wondering if you were able to straighten it out. I'm battling the same thing right now. I'm at the point where I'm trying to pull the Parker drive motor and can't seem to get it all the way you. It seems there might be a nut on the end of the shaft. So just scouring the internet for information. Thanks"
 
 
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