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Martin

weird hydro problem

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river-bottom tree farmer

The friend who found me the almost perfect D 160 (3-point, PTO shaft-driven 48" tiller) has been lusting after my rear end since his started leaking.  When he located a transaxle with turning brakes he did not need, but will be very helpful on my narrow, curvy trails, I paid the difference and we swapped.  I am having very similar problems with the hydrostatic system, with the exception I have all the speed I care to (and a little more!) in reverse.  Thank God I have not experienced the "blast-off effect" yet, and I have been able to throttle back on reverse.  At first I thought it was a linkage issue, but adjusting provided very little extra forward speed and then I noticed neither hydraulic cylinder is active and both were working fine before the switch.  It may be air in the system ( which was drained for transit and I replaced filter and put in fresh 10W-30) and perhaps I need to spend more time working it out (maple sap is finally flowing here, so that may have to wait) but I also have a part neither Dan nor I had seen before.  Could this transaxle have a remote accelerator valve connected by, I assume, a line in and a line out?  I mounted it on the inside of the left fender, where bolt holes lined up perfectly and the hoses just reached.  It is a rectangular box with cylindrical ends; lines are attached on the bottom of these and on the ends are Allen-headed bolts, which I assume to be for adjusting flow.  I found one diagram in a manual that appeared to have such a thing, but I can find no procedure for adjustments.  After more effort to bleed the system, I am lost.  I guess it would be helpful to see where the lines from this device connect, but I won't get back to the woods for a couple days. The other variable is that my previous transaxle had a band brake that had an interlock with the hydro linkage, and the current one does not.

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gwest_ca

This may be it

 

Garry

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pfrederi

The device is a dampener assembly that was added to the D series after a year or two.  Then deleted later in production.  it is to save wear and tear on the hydro from people moving from forward to reverse too quickly.  It is not necessary for proper operation.  The hoses should connect to 2 ports on the bottom side of the hydro motor.  If yours is not hooked up I would leave it out of the equation for now until you get teh unit to work properly.  Then if you want you can add it back.

 

 

Did you reuse your hydro motor or the one that came with the new transaxle?

 

 

If your lifts are not working it is a problem with the charge pump or possibly the bypass valves.  Does the tractor move at all?? Did you you use the correct O rings and backers on the connection between the hydro motor and the manifold coming from the pump?  Any leaks there?

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coldone

If its too fast in reverse, check the motor housing. it should have the webbed side up and the rounded side down.

 

From the manual service notes

 

Motor Section Note that the webbed section motor housing must
of
be "up" (Fig. 74), or motor will run opposite the intended direction.
 

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JamesBe1

Martin, any luck yet?

Here's a stupid though to throw out - give it about 1/2q extra in the tranny.  See if there is any change.  The whole issue sounds like it is being starved for oil.  On the off chance that the dipstick is wrong, you will notice it right away by adding a little extra oil.

After that, I would pull the hydro motor and check the screen.  That is a lot easier than pulling the hydro pump which will probably be your next step.

Good luck and let us know how things are progressing.

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Martin

Martin, any luck yet?

Here's a stupid though to throw out - give it about 1/2q extra in the tranny.  See if there is any change.  The whole issue sounds like it is being starved for oil.  On the off chance that the dipstick is wrong, you will notice it right away by adding a little extra oil.

After that, I would pull the hydro motor and check the screen.  That is a lot easier than pulling the hydro pump which will probably be your next step.

Good luck and let us know how things are progressing.

 

no real progress with mine. ive worked out if i just move the dcl a small amount and let the hydro 'fill' itself, then it will grab drive and go without being harsh...... i think the screen is probably the culprit, but until i get some time to work on it who knows?  i will try the extra fill and see what happens.....

the c160 isnt real high on the priority list right now. its probably going to stay how it is in all its rusty patina glory, ive fixed all electrical and repaired the rusty oem muffler, but as far as anything else goes, its just sitting covered up. too many other projects, kents 875 to finish, maybe a c175 build, and the cub 682 is probably getting a refresh for the summer......

 

oh, and my wife wants me working on the house as soon as the weathers nice. and thats a whole summer long and more project....... :angry-cussingblack:

Edited by Martin
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MalMac

I think my wife read the same book.

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Martin

im thinking of messing with the trans in this one again. i got it out yesterday and charged up a battery, rode it around a little and generally fell in love with this thing again. its a real nice original tractor and drives real nice after i deal with the initial 'take off' with the trans. i just read through the whole thread to refresh myself again on what ideas and suggestions the members here came up with.

i also wanted to bump this and maybe have some more interjection before investigating the hydro internally.......

any more thoughts and suggestions anybody, all much appreciated!!!!  :thumbs:  

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Jeff-C175

If it's any consolation, my 175 (Sundstrand) has been doing the same thing for about ten years now.  I just 'nudge' the dci forward and wait... that way I don't get thrown off and have to chase her across a highway and down into a ditch, or worse have her T-bone the better half's Monte Carlo.

 

I thought it was an air problem and 'drainback' myself, and is one of the reasons that I finally repaired the leaking hoses to the lift cylinder.  No change.

 

I like the theory of the plugged strainer screen... it's worth a look I think.

 

I'm gonna hit the Sundstrand service manual and see if I can come up with something.

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Jeff-C175

The "Acceleration Valves" are suspect...  but still, air in the system could play a big part here too... air will go through the mentioned orifices a LOT faster than the oil will!

 

"The acceleration valves are placed in the circuit to limit vehicle acceleration to a safe rate.  With the control lever in neutral, oil is under low pressure throughout the circuit.  When the control lever is advanced, the circuit pressure increases, causing the oil on the high pressure side to bleed by the flats on the valve lands and into the low pressure side.  This high pressure oil continues to bleed to the low pressure side, by-passing the piston motor and holding the acceleration rate to a safe level during the time it takes for the acceleration valve to close against it's seat.  The delay in closing the valve is due to the time it takes the high pressure oil to bleed through the small orifice in the acceleration valve metering plug and into the area behind the valve."
Edited by Jeffpicks

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Martin

just wanted to revive this one with some news......

 

been fixing a few things, steering, front wheel bearings etc and giving this one some tlc as its been sitting for longer than i would have liked. i guess I've been too busy lately... :confusion-scratchheadblue:

 

wanted to report the hydro behaved itself for the first time yesterday. i thought it was weird when i pushed it outside to run it. (don't enjoy it launching itself across my garage with all the others in there.) well like i said, thought it weird when it was harder than normal to move, resistance from the hydro was the same as my other 'good' sundstrands. got it out there and fired it up, went to reverse out and no bang, no sudden movement, just drove like it should. went forward the same way. let the 160 sit for a while and ran it again. still behaving. 

 

we will see if the problem is fixed......

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can whlvr

well I hope your problem is solved,i have a 160 that I had professionally rebuilt,its a great tractor and feels real nice to drive,i do know that if she leaks that doesn't affect the motion,mine leaks from the cylinder like crazy ,and I doubt its air,the air would get pushed through after running for a few minutes,my 160 can only be pushed about a foot then she locks up,when it went bad it was easy to push all around

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