1976 C160 automatic loss of speed and hydro attatchment capability

[vdub_asher 2]

I just picked up a 1976 c160 automatic. She runs great and seems to be in overall fairly good condition. This is my first wheel horse so I'm a little new to the ins and outs of how they are built.

    So anyway, I let my cousin cut the grass with my c160 and he thought it would be a good idea to do a wheelie on the concrete. He popped up and quickly came back down but hit down fairly hard. Right when that happened the tractor lost all capability of raising and lowering for the attachments (it has hydro lift). Then I noticed that it also will not go full speed in forward or reverse. I had been using the tractor for a few weeks before this happened so I know it was all functioning properly. 

      What it seems like is either a restriction of fluid somewhere or a loss of pressure. The attachments will not raise up at all even with nothing connected to it, the cylinder will not move. If you run at full acceleration it will get up to speed but then it is as if it doesnt have fluid to pump or doesnt have pressure because it will all of a sudden come to almost a complete stop out of nowhere, then build pressure again right before it stops and start going again. It will keep doing that at full acceleration forward. If I lightly stay in forward it will maintain a constant speed but if I go past halfway it will go that. 

        Reverse is also very weak and sometimes it takes a few seconds for it to even engage, especially when it is first started. 

       I'm not sure where to start really. I have checked the fluid level (at least I think I did it right) which seems to be fine. It seems to have to have the correct fluid, motor oil, not transmission fluid. 

       Not too sure what line pressures should be and all that. If anyone has any diagnostic help it would be much appreciated. 

Edited September 30, 2018 by vdub_asher

[roadapples 6,983]

I would disown that cousin....

 

[vdub_asher 2]

1 minute ago, roadapples said:

I would disown that cousin....

 

Yeah I was pissed....I dont let anyone touch it anymore. Lol 

[pfrederi 17,886]

Welcome to Red Square.   The Charge Pump powers the hydro lift...it also feeds the actual hydro pump that runs the hydro motor and makes tractor move.  If it is not providing adequate pressure the hydro lift will work weakly and the tractor will lack speed power.   Strange that you have no lift but still have some movement.  There are some relief valves that have springs wonder if the shock of the landing jammed or broke one (Implement relief or Charge pump relief)  You can download the service manual for a Sundstrand hydro here.  it has a diagnostic section but nothing seems to match your symptoms.

 

If you have a pressure gauge you should check the Charge pump pressure. 

 

Sort of stumped here at the moment.

 

 

 

 

 

[nylyon-(Admin) 7,334]

Check that the drive belt is engaged and not slipping.

[squonk 41,360]

Broken frame where the trans mounts causing enough movement to loosen the belt? 

[pfrederi 17,886]

No lift but still some movement, the piston block in the pump is trying which I would assume means it is being turned by the drive belt..  If the implement relief valve had failed in the open position maybe it is bleeding off so much charge pump pressure that the piston  to piston portion is staved for fluid????  (would also explain why no hydro lift....

[953 nut 55,836]

Sorry to hear about this, I think Paul has you headed in the right direction. Please keep us posted on your troubleshooting progress.

[daveoman1966 3,762]

I'm with SQUONK on this one.  The hard landing likely broke the trans mount plate and let the tractor almost split at that connection.  That is a weak point of the Wheelhorse tractors and a very common failure.  With that mount broken, the tractor will almost flex up/down, which is detrimental to the nylon CAM  (5996) and CONCENTRIC (5995) connection/motion...they MAY separate and this usually breaks the cam.

Lift off the hoodstand cover plate and have a look to see if that cam is broken, split, or out of position.   Referring to items # 129 and 130 in this schematic

    

[vdub_asher 2]

Drive belt is engaging and is not slipping.

1 hour ago, pfrederi said:

No lift but still some movement, the piston block in the pump is trying which I would assume means it is being turned by the drive belt..  If the implement relief valve had failed in the open position maybe it is bleeding off so much charge pump pressure that the piston  to piston portion is staved for fluid????  (would also explain why no hydro lift....

 

Now this sounds like it could be something. I'm gonna try and research the operation of the implement valve to see how it works inside and making sure I have gaskets to reassemble if I need to disassemble if needed. 

So I really think we might be on to something with this. I just drive it around the yard for a few minutes and if I held the implement lever in the lifting position while moving forward it would stay at almost full acceleration the whole time with only minor slow downs...hardly noticeable. 

[pfrederi 17,886]

I agree that a broken frame is possible but that doesn't explain the lack of any hydro lift. Something is wrong with  a relief valve....

Edited September 30, 2018 by pfrederi

[953 nut 55,836]

58 minutes ago, vdub_asher said:

I held the implement lever in the lifting position while moving forward it would stay at almost full acceleration the whole time

Bingo, Paul was correct (again). It isn't able to bypass while the lift lever is held.

[Sarge 3,463]

I'd start with the possible obvious result of a hard shock load - input pulley key may be sheared. Otherwise, a broken rear frame plate would be the best guess.

 

Sarge

[richmondred01 2,239]

I agree with davoman and squonk and 

I may have a solution to your issue. A frame and transmission transplant.

dont laugh I sent you a message. I have a rolling frame and sunstrand transmission from a 14 hp bronco that should work.

Edited October 3, 2018 by richmondred01