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View Full Version : Bobcat ZTR no right side drive


CT18fireman
02-16-2008, 07:32 PM
I have a Bobcat ZTR with a 25hp Kawi. It has about 2000 well maintained hours but has been used as backup, secondary for the last couple years. It was working well when we parked it in the corner this fall. Went to move it today and no right side drive. The pump whines like it is working.

So far I checked all the lines are tight. Releif valve is closed tight. Checked the linkages and they are tight and not binding. Jacked unit up and wheel turns fine by hand no clicking or catching it feels just like the left side. When you engage it in the air the wheel operates forward and back. I ran it this way thinking it had air in it but after 30 minutes I could still stop the wheel from turning with my hands and on the ground it will not turn. In the air the pump has almost no whine until it has resistance from the wheel then it whines. The left side is working fine.

I was going to change the fluid again before spring. It was done last at 1500 hours. This machine is really in good shape so if I have to put a pump in it I am fine with that just want to be sure.

Before I spend the $400 on a pump etc what else should I check? Or is it the pump?

MowerMedic77
02-16-2008, 11:33 PM
The pump whines like it is working.

So far I checked all the lines are tight. Releif valve is closed tight. Checked the linkages and they are tight and not binding. Jacked unit up and wheel turns fine by hand no clicking or catching it feels just like the left side. When you engage it in the air the wheel operates forward and back.
Before I spend the $400 on a pump etc what else should I check? Or is it the pump?

The only thing you did'nt list as checking was the belt/tension on the belt and the input pulley mounted on the pump shaft. Most of the pulleys are keyed on a straight shaft and locked down with set screws. A few are keyed onto tapered shafts with lock nut holding them down and I have seen both styles loosen up and break the key. Just a couple more things to check before you move onto the pump itself.

CT18fireman
02-16-2008, 11:47 PM
Good Point. I did check the belt. It is spring tensioned. Its tight but I can push on it enough to stretch the spring. Belt itself seems fine. I will have to check the pulley, I know it has a large nut on the bottom of it. I will have to see if the key is in place. Maybe just pop it off to verify.

I do know that the belt makes less contact with this pulley then the left side pump. On the left side the tensioner makes the belt wrap more then half way around on the right side it is far less. As I said though it is spring tensioned and has worked for years.

I will take a look tomorrow. Never had a pump go on a ZTR used to have the hydraulic trans go on Grasshoppers though. Is the pump more often the culprit or wheel motors?

MowerMedic77
02-17-2008, 09:04 AM
Is the pump more often the culprit or wheel motors?

The pumps are more common to fail.

Landrus2
02-17-2008, 09:39 AM
Will this be any help? :drinkup:

MowerMedic77
02-17-2008, 10:27 AM
Good Point. I did check the belt. It is spring tensioned. Its tight but I can push on it enough to stretch the spring.
I do know that the belt makes less contact with this pulley then the left side pump. On the left side the tensioner makes the belt wrap more then half way around on the right side it is far less. As I said though it is spring tensioned and has worked for years.

I always use the spring as my guide for belt tension, if the coils on the tension spring are all touching and have no gap between them then in most cases its time for a new belt.

CT18fireman
02-17-2008, 11:01 AM
Good thought I will take a look at the spring.

I have the J-thomas catalog. Right now I am still diagnosing, once I find the problem then I will look for repair. Probably just get a new pump and then rebuild that one as a spare. Got to flush out the system, change the fluid and filter etc either way. Just want to be sure it is the pump that it bad.

themowerman
02-18-2008, 09:53 AM
Did someone by any chance open the bypass valve??? If it is open a little it will mimic what you are telling us.......

MowerMedic77
02-18-2008, 10:10 AM
Here is part of his original quoteSo far I checked all the lines are tight. Releif valve is closed tight.

CT18fireman
02-18-2008, 10:41 AM
Yeah its tight. I did not get a chance to look over things again yesterday. Had a customer come up for the weekend and find some storm damage on his property and then wanted to watch the race. I will take a look later today as its raining anyway. Just going to recheck everything and check the keyway.

Probably just going to order a pump for it, looking at the diagram I would think that the case gets scored and by the time you order all the pieces to rebuild better to just get a new one. New filter, fluid belt etc.

themowerman
02-18-2008, 05:56 PM
Sorry...didn't read it that close...Don't get your panties in a bunch there medic....relief valve is different than tow valve if you want to get technical.......CT18...have a flow test and wheel motor test on her before you replace it......

MowerMedic77
02-18-2008, 06:24 PM
No panties, so no problem there mowerman..........

CT18fireman
02-19-2008, 11:19 AM
I did check the pulley and keyway, everything good there. Running it still turns the wheel in the air but slips with the wheel on the ground.

I noticed that the left or good side with the motor off and releif valve closed the wheel turns slowly forward and can't really be turned in reverse.

On the bad side it moves both ways rather easily and there is a sound in the pump as I turn the wheel. There is no sound on the good side. When I loosen the releif valves both wheel motors sound the same as they turn with no resistance.

I was hoping to avoid the flow test as the dealer will probably want $200 for that plus want to do the repair and he has a huge markup in parts here. $360 for the pump from J-Thomas and he will want over $500 plus labor. So it will be close to a grand. For that I could get a pump and wheel motor and do the whole side myself.

themowerman
02-19-2008, 12:35 PM
Now that we have more info, it does sound like the wheel motor and possibly the pump are bad. If you can borrow a flow meter and do your own flow meter test you can test the pump first then the wheel motor. But from what you are saying it sounds like the wheel motor went south on you. It probably also took out or is taking out your pump also. Make sure you flush out the hoses and tank real good when you replace the pump and wheel motor. After you change out the pump and wheel motor you need to purge all of the air from system. Jack up machine and open bypass valves, run machine 3/4 throttle and slowly cycle control handles forward and reverse for a few minutes. You will want to do this until air bubbles are not seen in hydro oil any more. Then you can close valves and cycle again. That should purge all air from system.

From manual....
Initial wheel motor test.
1. A good wheel motor should turn hard in forward. With unit jacked up and jack stands under unit, grab the tire and try to rotate it forward.
2. A good wheel motor should not turn in reverse.
3. If the wheel motor turns easily and or clicks while turning, the wheel motor may have internal damage.

Wheel motor stall test.

1. To check wheel motor leak through, install a bi-directional flowmeter at the inlet port of each wheel motor.
2. With flowmeter plumbed in, put the machine up against a solid object. Run the engine at full throttle.
3. Move the drive handle in the forward direction. Watch the pressure gauge on the flowmeter, when it reaches 3000psi, read the flowmeter. There should be no more than .5gpm registered. This is the allowable limit.
4. Rotate wheel 45 degrees and repeat test. Repeat this process eight times for each wheel.

You need to test the pump first to make sure you have a viable pump to do this test. Hydro system temp also needs to be at normal operating temp....from 160 - 210 degrees.

This is just a sample of one of the testing procedures...each pump and wheel motor mfg has their own procedure.

Hope this helps.

Jay19LM
02-19-2008, 03:55 PM
You said it was working well when you parked it. I would fiqure out what happened from sitting. Did it leak out any hydro oil. Before I would replace the pump, you might take it out and have a trained tech look at it. I have repaired just as many as I have replaced.

CT18fireman
02-19-2008, 04:59 PM
No leaks. This is the first time it has been moved. That's what has me puzzled. It run 20W50 oil for hydro fluid so I drained that out today and checked the filter, no extreme amount of shavings or anything. Oil looked pretty clean for being around 500 running hours old.

If I had a good wheel motor not hooked to the pump would it turn both directions? If I took the hoses off the good left motor it should turn just like opening the releif valve right?

It really feels like the releif valve is open but its definately down tight, I have opened and closed it a few times now. Just that wheel can move around freely, but the pump is making enough flow to turn it in the air but not enough pressure to turn it on the ground and when its not running will not hold the wheel still.

This has been a great mower and I have the belt driven catcher, jrco setup on the front etc, so I am willing to put some money into it. I just hate the thought of tearing a good part out.

J&R Landscaping
02-20-2008, 12:16 AM
Out of curiosity,,, put an extendable magnet into the hydro oil tank, go all the way to the bottom and rotate it around a few times. If any, how much metal shavings do you get out of there?

I replaced a pump and motor combo last summer on a friends machine and I was really surprised as to the high content of metal in the system. Even after the system was flushed, and test run, there was stilll some shavings in the system. No where near as much in the beginning but some none the less.

CT18fireman
02-20-2008, 11:18 AM
Well I took the pump off and apart today. Very few shavings in the pump or resevoir. I did however find some pretty good scoring/wear in the cylinder block (part 46 in schematic) and in the top cap. I did not take the check valves etc apart as I am going to order a new pump for it.

CT18fireman
03-11-2008, 04:04 PM
Finally got back to this today. I had ordered a pump, filter, belt etc but then we had more snow and other things come up.

Today I got the pump on, flushed everything, changed engine oil and tuned while I was at it.

Started up and tried to bleed it. Spent 20 minutes and still had a lot of foam. Let it sit for a bit, came back bled it again and oil finally cleared up. Runs nice now, got to adjust the linkage just a bit and I should be set.

Never found any shavings or anything severe. I have a feeling it was a pressure valve or releif valve stuck a bit cause it was still flowing oil. In the ong run though was just as easy to replace the pump and be back in business.

Now just have the walkbehind to tune and I will be ready for spring. Probably 2-3 more weeks before we start here.

Thanks Guys