No power steering on a Terramite

[wdchyd]

Hydraulic shop thought something significant must have gone through that pump to tear it up so badly. My job would become to make sure there is nothing still in the system to hose me again.

When the significant stuff went through the pump did it go through the barrel and get caught between the face of the barrel and the valve plate?

Did it look like it went where the red and blue oil goes in the pix?.....or did it look like the piston slipper/shoes were torn up instead?

 

[cstamm81]

thread revival... I am not sure where the significant stuff went through, the hydraulic shop did not specify. They only said there is significant damage, and it as very far from normal. I spoke with them again today and they are telling me they will rebuild the whole thing for under 1200 and bench test the assembly. He is telling me he will be replacing the whole rotating group, sealing everything. Said he will check out the aux rear pump but said it looked fine. Mentioned something about a rear cover being gouged, but said it will be replaced. No written warranty, more of a gentleman's agreement if by chance they would assemble something wrong.
I mentioned the torque motor with the damaged mounting flange and he wants to take a look at that to make sure there is no potential internal damage. My guess is I would be in the neighborhood of 1500 to have them inspect and rebuild everything, and I could get it all brand new for 2200 plus shipping from Terramite. Decisions decisions...

 

[cstamm81]

In an effort to think through potential issues if I pull the trigger on a rebuild or replacement... I want to verify operation of the initial issue, lack of power steering. My fear is there is ALSO something going on in the steering box / diverter valve. Or, and maybe this is far fetched, the steering circuit has not had operating pressure running through it for who knows how long, so who knows what to expect when the pressure is restored with the new/rebuilt pump.
So, being as I have another perfectly operating Terramite T5C in my possession, I got to thinking. Would it be possible or advisable to try the following: Disconnect the power steering line from my working tractor and plumb it into the steering box of the non working tractor. Run the working tractor and check for proper steering operation / leaks on the non working tractor. I know this will drain fluid from the working tractor and return it to the tank of the non working tractor. I had even thought of catching the oil returning to tank in a container for evaluation, seeing as the steering circuit has not seen full pressure in awhile. It is time to change fluid in the working tractor anyway, and I am assuming I could run it for a minute or two easily before running the reservoir level down enough to starve the pump.
So, is this a good idea? Is there anyway I'm missing as far as system pressure on the working tractor? I am not sure how the charge circuit works, but the last thing I want to do is create a problem on the working tractor.

 

[wdchyd]

Sure, that will work.......you could catch the return flow in a clean bucket to replace it in the donor tractor or run a temp hose back to donor

At work we have a hyd power unit with variable flow/pressure and many times we have done this exact thing......at least you will be able to set your mind at ease when you test out the steering circuit

as far as the rebuilt stuff, replacing the rotation group is the right way to do it, but in my mind if the repaired/rebuilt goes beyond 60% you should be cautious, they should give you some kind of warranty (which would likely be void if they find contamination damage anyway)

 

[cstamm81]

I am going to try and get to the hydraulic shop in the next week or so and see the damage myself. His best guess is the damage may have been caused by over-speeding of the pump? He did not believe it was due to metal going through, but was really only guessing. I mentioned the system calls for 15w-40 motor oil, and asked if damage could have been caused by someone using hydraulic oil instead. He seemed baffled why Terramite would call for 15W-40, said that universal tractor fluid covers most systems. Mentioned that if hydraulic oil and oil were mixed it would be a no no. Comment was he and his worker have been doing this each for 15 years and have not seen anything quite like this. I do wonder if a different shop could do the same rebuild for much less $$$.

I spoke to him about the damaged torque motor, and he did not believe he could rebuild it and replace the broken mounting flange section for much less than the $600 TM wants for a new one.

 

[J_J]

It is hard to believe that a good hyd shop did not know about the use of motor oil in hyd systems.

 

[cstamm81]

that struck me as a little odd as well. This SEEMS like a well run, established place. I only found it based upon a recommendation from a guy I respect, but that's all I know about the place. He did mention some Bobcats (I think) call for straight 30 weight oil, he just didn't seem like he knew why OEM's would call for motor oil in the systems.
Terramite warns in big letters on the first page to not use hydraulic oil, as pump damage will result. I do wonder if the severity of the damage to the rotating group could have been caused by a previous owner using hydraulic oil in the system.
I had entertained having the shop throw the pump back together and I would reinstall as is, as the machine did operate (without power steering and some obvious pump issues) before I took it apart. The guy told me he was surprised the tractor moved with the pump in such poor shape, and mentioned it may develop decent pressure with the oil cold but as it warmed it would most likely lose pressure. So it sounds like that idea is down the toilet (and silly in the first place).

 

[wdchyd]

It is hard to believe that a good hyd shop did not know about the use of motor oil in hyd systems.

most industrial systems don't use motor oil but rather 10w (ISO-VG32) and 20w (ISO-VG46) so it doesn't surprise me they didn't know......it seems the only time we see motor oil is when the manufacturer uses components that are over heating ( reservoir too small or components working too hard) and worry about the oil being too thin accelerating wear on internal parts

ZTR mowers are a good example, they run hot and don't get oil cool enough

 

[ChippyMcGee]

I read this thread about a month ago when I was looking at a 1990 T5C that I thought had a power steering problem. Turns out the 1990 model has manual steering (no power steering from factory). I bought the machine and it has trouble with forward and reverse. If I go forward or reverse slowly, there is no problem - plenty of power and smooth. If I try to go faster in forward or reverse, the motion is jerky and erratic, as if a chain was slipping (I know there's no chain). I found online the Eaton Service Manual for the variable displacement hydraulic pump model #70142 (aka hydrastatic transmission) - (see link below). It says to check the charge pump pressure at the charge pump access plug (i.e. remove the plug and connect pressure gauge) on bottom of pump. Haven't done this yet since I don't have a new o-ring to replace when reinserting the plug. Anyways I wanted to pass along the link to manual. I believe you can order the "Adapter Plate" that was mentioned earlier from Eaton - just find the manual for your pump (hydrostatic transmission as Terramite calls it) on that we page, get the part number and order it from Eaton/Vickers.

http://www.vickershydraulic.com/site/pdfs/07-623.pdf

 

[ChippyMcGee]

P.S. - From what I read, and as others have mentioned, the power steering pressure comes from the charge pump output, which should be between 100 - 300 PSI. The Eaton manual says that you can check charge pump pressure at the port (after removing plug), but it's probably the same pressure you'd measure at the power steering line. The manual also says that if charge pump pressure is low, then check charge pump pressure relief valve, which I believe is what others found to have pushed through its seat in the adapter plate. Manual says if charge pump pressure is low but relief valve checks out OK, then "replace pump and motor."