680 ck shuttle/torque converter

ajo

New User
I,ve got an older 680 that will not move forward or backward. the pump, valve body and torque converter were replaced by previous owner but still only builds 40psi off pump. any other ideas on where problem may be coming from? Clutches seem to be new or very good. the machine tried to move when shuttle was engaged but would more or less just rock in direction selected. thanks for any help
 
Does it load the engine when you shift from neutral to forward or reverse? If so it might be locking both clutches up.
Later Bob
 
does not load up the engine. if you rev up throttle in gear it will just barely creep. manual says pump pressure should be 140 psi +/-.
i can only get about 40 psi. not sure if a faulty converter would allow pump circuit to not biuld pressure?
 
I'm not familiar with the model, but just some general thoughts: I'd make sure inlet to pump is clear (filter plugged?) and is there a bypass/relief circuit that may be stuck open? My guess is that the problem is before the T/C, especially since it had been replaced. Also, did you get it with this problem or has it worked correctly for you since you've had it? In other words, did the previous owner botch the rebuild job?
 
There should be a relief valve to set up clutch engaging pressure 140 Psi and then the oil dumpimg from it go into the torque converter. Could be a worn out pump, stuck open relief valve or some place the pump outlet oil is leaking to inside the case. Not too familliar with your tractor but that is common to most. On a good system they usually hold 90% of the pressure you read at full throttle when you throttle down to low idle. If you raise the rear wheels and have good pump flow it should spin them fast I would think, 40 psi should engage a clutch with no load on it. If not likely not enough oil is getting into the torque.
Later Bob
 
machine has never worked since i've had it. i'm thinking that the pick-up may be the issue. there was a clump of "fibers" in the screen. not covering the whole pick-up but probably enough to restict flow.
 
(quoted from post at 06:52:45 11/28/09) Does it load the engine when you shift from neutral to forward or reverse? If so it might be locking both clutches up.
Later Bob

I have a Case 680 that goes forward fine but you have to rev up the engine to get it to move in reverse and it feels like you have the brakes on. Your thought about both clutches being engaged seems logical as the engine does lug down when I shift into reverse. What has to be done to fix this problem?
Rick
 
(quoted from post at 15:05:57 11/30/09) machine has never worked since i've had it. i'm thinking that the pick-up may be the issue. there was a clump of "fibers" in the screen. not covering the whole pick-up but probably enough to restict flow.
I trust the oil level is right up to the full mark with the engine running. They can act a bit similar by simply being low on oil. Checking the transmission oil level cold before starting is very deceiving.
On one 680 I had the flex plate was cracked and the oil pump for the transmission failed to engage properly. It acted much like you describe.
 
I drained out the fluid and cleaned the filter screen. I also took out the relief valve spring and check ball and quite a bit of fluid came out of there. I then added new Case Hy-Tran fluid to it. The manual said it should take 12 quarts but it came out of the filler tube at about 11 and was a little over the full mark after I started it, shifted it back and forth and then checked it. I ran it for a while and checked it again and it was still over the full line some. It now seems to shift good into forward and reverse but will not allow me to shift the transmission when in neutral. I have to shut off the machine to shift gears. It also doesn't seem to be locking up well in forward. If I put it in fourth gear it won't even get going. It just revs up and sits there. It will go in the other 3 gears but seems to slip the least in 1st. Also, I got the clutch cut out working but when I activate it the transmission still doesn't disengage. Any thoughts would be appreciated.
 
(If I put it in fourth gear it won't even get going. It just revs up and sits there. It will go in the other 3 gears but seems to slip the least in 1st. Also, I got the clutch cut out working but when I activate it the transmission still doesn't disengage. Any thoughts would be appreciated.

If you get your hands on a manual that covers the fwd/rev transmission it shows you all the 1/8" plugs where you can install a gauge to show pressures throughout the system during fwd neutral and rev. You will be able to draw some very logical conclusions for what needs to be addressed.
 
(quoted from post at 10:20:51 04/25/16)
(If I put it in fourth gear it won't even get going. It just revs up and sits there. It will go in the other 3 gears but seems to slip the least in 1st. Also, I got the clutch cut out working but when I activate it the transmission still doesn't disengage. Any thoughts would be appreciated.

If you get your hands on a manual that covers the fwd/rev transmission it shows you all the 1/8" plugs where you can install a gauge to show pressures throughout the system during fwd neutral and rev. You will be able to draw some very logical conclusions for what needs to be addressed.

Thanks,
I do have a repair manual and parts manual for it so I'll have to check out the pressures next. The tractor is up north at our cabin about 3 hours from here so I'll be going up next weekend to continue my work on it.
 
(quoted from post at 21:38:17 04/25/16)
(quoted from post at 10:20:51 04/25/16)
(If I put it in fourth gear it won't even get going. It just revs up and sits there. It will go in the other 3 gears but seems to slip the least in 1st. Also, I got the clutch cut out working but when I activate it the transmission still doesn't disengage. Any thoughts would be appreciated.

If you get your hands on a manual that covers the fwd/rev transmission it shows you all the 1/8" plugs where you can install a gauge to show pressures throughout the system during fwd neutral and rev. You will be able to draw some very logical conclusions for what needs to be addressed.

Thanks,
I do have a repair manual and parts manual for it so I'll have to check out the pressures next. The tractor is up north at our cabin about 3 hours from here so I'll be going up next weekend to continue my work on it.

Well, I was able to get to the check point for pressure on the torque converter and it was right where it should be. The other check points are on the top of the manifold which is very difficult to get to. I drove it around again and it continues to act the same. The machine will not shift the 4 speed when the shuttle is in neutral. I tried re-adjusting the linkage and couldn't get it to work. Sometimes I can get it to shift when it's in reverse otherwise I have to shut it down to shift to a different gear. It works great in reverse but does slip in the higher gears in forward. Is it time to remove the transmission and check out the clutches?
 
Sometimes I can get it to shift when it's in reverse otherwise I have to shut it down to shift to a different gear. It works great in reverse but does slip in the higher gears in forward. Is it time to remove the transmission and check out the clutches?

Have you tried shifting gears quickly as you move the fwd /rev lever to the opposite direction? With slipping in forward it may be that the fwd clutch pack is tired and needs replacing but if you can access the pressure plug for forward oil pressure you may just have tired or damaged seals so the pressure to fwd clutches bleeds off and the clutches don't have enough grab. If you can do all the repair work yourself you can keep cost down but at a rebuild shop it won't be cheap. If you can get a rebuilt unit with exchange price it's easier to know what $$ you'd be at in the end.
 
(quoted from post at 10:11:25 05/07/16)
Sometimes I can get it to shift when it's in reverse otherwise I have to shut it down to shift to a different gear. It works great in reverse but does slip in the higher gears in forward. Is it time to remove the transmission and check out the clutches?

Have you tried shifting gears quickly as you move the fwd /rev lever to the opposite direction? With slipping in forward it may be that the fwd clutch pack is tired and needs replacing but if you can access the pressure plug for forward oil pressure you may just have tired or damaged seals so the pressure to fwd clutches bleeds off and the clutches don't have enough grab. If you can do all the repair work yourself you can keep cost down but at a rebuild shop it won't be cheap. If you can get a rebuilt unit with exchange price it's easier to know what $$ you'd be at in the end.
I haven't tried shifting gears while moving the Fwd/Rev lever. I'll have to try that when I go up next weekend. If I remember correctly I believe there is one port that you measure the FWD/REV pressure and not a separate port for each. I have the manual up there so I can't verify that for sure. I'll check on that also when I go back up there. I'm thinking I better start looking around for a rebuilt unit like you suggest. As old as this thing is it doesn't surprise me that it would need a rebuild. Thanks for your help. I'll let you know what I come up with next time up there.
 

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