HYD TRANS REBUILD/RUNNING GREAT FOR 20 MIN THEN LOOSING PPWER

[Don C]

HI YALL,
I am a first timer looking for input with some of the more seasoned techs out there. I gave a small shop my left trans from my RZT 50 CUB CADET to rebuild and $450.00later, he said it was done, after having torn it down and rebuilt twice. When I picked it up, it ran worse than when I dropped it off to him. Plus, I footed the bill for all the parts of which were 2 filters, one for my trans, one for him to keep in stock, as well as the 4 thrust bearings (2 of which went into my trans and 2 for his stock). Having forgiven him and picking my mower up, I decided to tear it down myself. After dis-assembly, I discovered he had not even changed, not to mention, clean the existing filter. Sooo, I proceded to order the 2 new pumps, after carefully inspecting all other parts, and reassembled it. After loading it with 40 wt non detergent and 1/2 pt tranny fluid, I purged it, adjusted the linkage and took off mowing. It ran like a new machine for about 20 minutes then started slowing down in the left with the right being ok. I'm not sure of what I can do to make a fix and thought I would reach out. By the way, the small retainer pin in the mail pump shaft was installed properly, after I got the heck of how to keep it in place. I'm confident of reassembly, but am looking for guidance on how to keep the trans running consistantly. Any ideas?

 

[Carscw]

Sounds like the oil is getting hot and to thin.
Most hydros use 20-50 oil

 

[Don C]

Thank you for the comeback. Now if I suck the remaining oil out of the tranny, how much would be enough to replace with the proper viscosity--I know its not exact but in your pro experience, could I get a quart out?, then replace it with, say, 80-90?? Another thing I thought of was cavitation. Air could cause the down power syndrome. The unit was full, bench run before re-installation, and refilled to w/i 1/2 in. I remember may decades ago when the old hydro dozers would get weak, the boys would put 80-90 in the reservoir (I don't know how much) and those implements would push a house down.

 

[Catherine]

Welcome to the forum. :welcome:

I'm going to move your thread to see if we can get you some more answers.

 

[Carscw]

You should be able to get most of it out threw the breather hose.
First thing I would do is lift the wheels off the ground and start the engine and put it in full forward. About 30 minutes.

 

[Don C]

You should be able to get most of it out threw the breather hose.
First thing I would do is lift the wheels off the ground and start the engine and put it in full forward. About 30 minutes.

Thanks Carscw. I'll do that. Actually, it seems to me that I could remove the fill plug and get more liquid out because of the hose going deeper into the tranny after its warmed up and I shut it off. The oil should be good and warm about this time. I was just thinking also of mowing with it till it started getting weak; then bring it in the shop and jack it up and do what you suggested to do. It certainly won't hurt anything, and will get more grass cut.

 

[bertsmobile1]

Thanks Carscw. I'll do that. Actually, it seems to me that I could remove the fill plug and get more liquid out because of the hose going deeper into the tranny after its warmed up and I shut it off. The oil should be good and warm about this time. I was just thinking also of mowing with it till it started getting weak; then bring it in the shop and jack it up and do what you suggested to do. It certainly won't hurt anything, and will get more grass cut.

I did not jump in because Carscw was responding & I am not familiar with this particular machine.
The first thing that concerns me if I have read it right you got charged for work that was not done and parts that were not fitted.
If that be the case it is fraud and needs to be redressed we can do without shops like this. It makes things bad for honest shops who do good work.
At the very least, name and shame the shop.

Next most of the tranny companies have on line manuals and all hydro boxes are basically the same.
Some times I have needed to bleed the "bleedin" box a dozen time till it all the air is purged properly.
Finally, the one thing that varies in boxes is the oil they are designed to run and they can be very sensative to both the oil and the filters used.
When I did the first box it called for Mobil 5W=50 fully synthetic. I used a different brand of 5W-50 fully synthetic and the box never ran properly till at a latter service I drained the box, flushed it with the Mobil , refilled with the Mobil ( at my own cost ) and now it is working perfectly.
I noticed you have put some sort of a blend in and that might not work properly.
The pistons on the pump & motor have no seals and rely on the close fit to pump more than bleeds down the sides and this ( amazing when you think about it ) is tailored to the viscosity of the recommended fluid

 

[Don C]

I did not jump in because Carscw was responding & I am not familiar with this particular machine.
The first thing that concerns me if I have read it right you got charged for work that was not done and parts that were not fitted.
If that be the case it is fraud and needs to be redressed we can do without shops like this. It makes things bad for honest shops who do good work.
At the very least, name and shame the shop.

Next most of the tranny companies have on line manuals and all hydro boxes are basically the same.
Some times I have needed to bleed the "bleedin" box a dozen time till it all the air is purged properly.
Finally, the one thing that varies in boxes is the oil they are designed to run and they can be very sensative to both the oil and the filters used.
When I did the first box it called for Mobil 5W=50 fully synthetic. I used a different brand of 5W-50 fully synthetic and the box never ran properly till at a latter service I drained the box, flushed it with the Mobil , refilled with the Mobil ( at my own cost ) and now it is working perfectly.
I noticed you have put some sort of a blend in and that might not work properly.
The pistons on the pump & motor have no seals and rely on the close fit to pump more than bleeds down the sides and this ( amazing when you think about it ) is tailored to the viscosity of the recommended fluid

bertsmobile1 from Don C,

This is excellent input. I will bear that in mind. I cherish the input I have received so far, and am taking everything into consideration. This sounds like the correct forum to be in. Everyone works as a unit. I am still boggled by the idea of thicker viscosity oil, when heated to temp, causing the hydro to run better, provided there is no cavitation. I presume to think that your idea of bleeding, even though I've done it several dozen times, is the problem. I haven't had a chance to run the machine for days now,but should be running it this pm. I'll stay in touch; again, you brothers are a step above, and I am humbled by this treatment. lThank you.