sundstrand odd problem

[NA73 70]

looking for some insight or something... tow/push valve?

 

here's the story:

1973 14hp 'no-name' auto w/ sundstrand.

 

this has been driving me mad for the past month. In new england, the last big storm we had where it dropped 12"+ of snow through most of north central mass. the wheel horse died in front of my neighbor's car and would not restart that day no matter what. I opened the push/tow valve and pulled it backwards with my truck (about 40ft) slowly, I'd say walking speed or slower to a spot where it can be for some time, if needed.

 

the next day, I get it started and start plowing again and the tractor develops a really weak reverse after a few minutes but still some decent forward power. consult with a friend who does tractor repair for a living and he suggested draining all the oil from the hydro and putting in fresh oil and making sure the linkage/chassis bolts were all tight.... 10w-30w is what was in it and what was refilled with and the hydro filter is changed every year and all the bolts were tight - did this on a saturday. After refilling, I turned the pulley on the pump over by hand with the trans in neutral.

 

Tested it out an hour later and it now had a weak reverse even when cold. Let the tractor sit until the following tuesday morning and it was back with full power in reverse and forward.

I don't remember if I opened and closed the push/tow valve at that time.*scratch head*

talking to a couple more friends -one a wheel-horse fanatic- suggested maybe an internal gasket getting ready to let go or it was a sticking valve.

 

I then let it sit due to 'rainy/wet/cold/mud season' new england spring weather for the past couple weeks. Last week I freshened up the engine with new piston/rings/gaskets. I pulled the engine off yesterday to double check something but had to move the tractor chassis so I opened the push/tow valve to push the tractor 4-5ft put the engine back on and this morning the tractor acted up with a weak reverse again after a few minutes. which makes me think something is wonky in regards to the push/tow valve - either a piece of crud/varnish or I-don't-know.

 

I've read through various wheel horse/sundstrand manuals but I have no actual repair/rebuild experience what-so-ever with the hydros.

 

I'm at a loss as to the how/why. anyone care to offer any ideas/insights as to the how/why or what I can try to rememdy this problem.

 

Edited April 10, 2017 by NA73

[NA73 70]

guess it's time to scrap the thing.

[pfrederi 17,887]

You looked at the Sundstrand manual.  Did you remove the tow valve to check the tip?

Can you push the tractor with the tow valve closed.?  if the tip is good and you cannot push it very far witht  valve closed then look at the erratic operation diagnostics.

 

Checking the various issues is pretty clearly explained in the manual. 

 

 

Edited May 25, 2017 by pfrederi

[953 nut 55,849]

On 4/10/2017 at 7:42 PM, NA73 said:

draining all the oil from the hydro and putting in fresh oil

Sorry I missed this one last month. It is not time to scrap it. What was the condition of the oil you drained out?  Could be a bit of foreign material (dirt) is lodging and dislodging itself in the area of the acceleration valves. Follow the steps in the manual and remove, clean and inspect each one and be sure the springs on both sides are good.

[diesel cowboy 263]

Bringing this back up to the top as I have it at work trying to fix it for the OP.  A little back story in it is he bought it a couple years ago from me and probably close to 10 years ago I traded a Ford LGT165 for it from a wheeler dealer customer at work who got it from who knows where for his son who got bored with it.  Put it on the bench on jack stands to drain the oil and take the hydro unit off.  Had to put another pan under where the hydro was to catch more oil and noticed that there was what looked liked paint chips coming out in it so I pulled the metal screen and it appears that the pain chips are whatever was used to coat the inside of the housing is finally coming off.  While looking inside I saw a bead of blue silicone on the housing halves so I know some one was in there at some point.  Pulled the pump housing cover leaving the motor and piston assembly sitting on the charge pump and end cap housing.  Checked over the pistons and slippers and found only minor light scratches and they moved freely in the block.  The block looked to be in good condition until I flipped it over and found a "deep" scratch on the back side where it rides on the valve plate.  Set that aside to inspect the valve plate and found this: 

Notice the piece of metal in the valve plate at about the 4:00 position.  The marks where it dug in while the pump was turning are bad.  So bad that to clean it up its easier to take it to a machine shop to have it turned and polished instead of trying to do it myself with a piece of glass and 1000 grit sandpaper.  Put all of those parts to the side while thinking about if its possible to use parts from a Cub Cadet hydro as they look the same.  Moved on to the drive motor part and pulled that apart and didn't find anything out of the ordinary that I'm not used to seeing when I open these up on the Cubs until I pulled the accelerator valves out and found this:

 

That's laying on the bench exactly as I pulled it out of the motor end cap.  Apparently when whoever was in the rear end they also went into the hydro and put this back together wrong.  If you look close you can see the valve on the left is facing the same way as the one on the right instead of both facing each other.  It made it so the spring wasn't seated properly and it broke while also chewing up the hex on the metering plug: 

The little "hairs" on it are from the rag I used to wipe the oil off.  In the picture with the spring you can see a tiny part that broke off close to the left hand valve which makes me believe the piece of metal stuck in the valve plate from the first picture is also from this spring.  At that point I decided to pick everything up send an e-mail off to the OP as it was late at night and started to pick everything up.  While pouring the oil into a clean jug because he had put new in before bringing it to me I found this in the drain pan:

Can't repeat what I said at that point but it was along the lines of crap and someone must hate me.  It looks to be part of a needle bearing to me.  The only question is knowing that this has been apart before is it a freshly broken bearing or left over from before and the rear end being removed from the tractor, put in a truck, brought to me and moved around to get it on the bench to drain the oil knocked it loose from somewhere?  Back in the first post he said he put new oil and filter in it so I would think that if it was a bearing coming apart since the last time it was opened up he would have found it in his drain pan.  As it stands now everything is going to be boxed up and put off to the side until he hears back from a friend of ours about the possibility of buying another complete hydro rear end to drop in because he wants it for the winter, and right now I don't really have the time to spend trying to patch it back together as I need to put my plow truck back together.                                   Stewart

 

[pfrederi 17,887]

That valve plate looks to be beyond repair. LJ fluid power has them.   Anyone who uses RTV in a hydro should be told to stay away...

 

Is this a piston to piston or hydro gear??  If piston to piston the hydro motor plate is probably in equally bad shape.

Edited October 4, 2017 by pfrederi

[diesel cowboy 263]

3 hours ago, pfrederi said:

That valve plate looks to be beyond repair. LJ fluid power has them.   Anyone who uses RTV in a hydro should be told to stay away...

 

Is this a piston to piston or hydro gear??  If piston to piston the hydro motor plate is probably in equally bad shape.

My dad has actually seen a valve plate that was worse about 25 years ago.  It was on a Case Uni-Loader that blew a line to one of the drive motors and when the new line was put in they pushed it through all the dirt and as you'd expect dirt got in the hose and they didn't try to clean it out just hooked it up and less than a half hour later it was toast.  Sent it to a machine shop and they were able to grind and polish it back flat, and as of about a month ago when I last saw it, it was still running strong.  So hopefully it can be saved if needed.

 

Its a piston to piston and the motor valve plate is actually near perfect.  A quick polish on the glass with sand paper and it should be ready to go again.