Case 680k won’t go forward

[Swampman711]

Hey guys I’m new to this forum I’ve been looking trying to find a thread about this and can’t seem to find one if you could point me in the right direction or maybe this will be the start of a new one for people to learn from thanks in advance!

I’ll do my best to describe what I have going on, I have a 1987 or 1988 case 680k, 2 wheel drive, ext hoe, 3speed shuttle shift, air brakes, my problem is I can’t not get the transmission to engage into forward every once in awhile it will want to go forward for a few seconds then acts like it pops out of gear but it does not make a sound like grinding or popping it just stops moving is all, reverse doesn’t seem to have any issues, I’ve checked fluid level it is clean and full, the air brakes are not working at the moment I have adjusted them so they are not dragging all the time I need to fix a few air lines. Not sure what other info you may need I’ll do my best to respond as fast as I can for you Guys thanks!

 

[Tinkerer]

The shuttle or the four speed gear box ?
Do you have the operators manual and service manual for it ?
There is a specific way to check the shuttle oil level.
Describe how you check it please.
It may be worn gear shift linkage. Or a worn detent in the spool in the transmission valve.

 

[Swampman711]

The shuttle or the four speed gear box ?
Do you have the operators manual and service manual for it ?
There is a specific way to check the shuttle oil level.
Describe how you check it please.
It may be worn gear shift linkage. Or a worn detent in the spool in the transmission valve.

I do not have a manual for It I just bought the machine a couple days ago, working on rebuilding a few cylinders and fixing what I can, I have been checking the shuttle by taking off the passenger side cover it’s just above the starter, I checked with it running, I’ve check the cables that operate the spools they seem to move full length, my thoughts were pointing towards a worm spool, looks kind of tight to get to

 

[Tinkerer]

I forgot that your K doesn't have a four speed gear box.
It could be the clutch cut-out switch or it's wiring among other things.
Have you cleaned the transmission screen and changed the spin on filter ?
They are most likely unrelated to the problem, but should be done since you haven't had the machine very long.

 

[Swampman711]

I have not yet, I plan on doing a complete fluid change, is there any wire testing I could do to find out if it is a power issue? Is it possible to run direct power or just unplug the solenoid?

 

[Tinkerer]

I almost forgot -----
Welcome to HEF, Swampman !
Unhook one of the wires on the switch on the transmission. That will eliminate a entire circuit from interfering with the transmission operation.

 

[Swampman711]

I almost forgot -----
Welcome to HEF, Swampman !
Unhook one of the wires on the switch on the transmission. That will eliminate a entire circuit from interfering with the transmission operation.

Thanks! And when I get out of work today I will give that a try, I will also check the screen if I have time tonight

 

[Swampman711]

Do you happen to have a diagram showing what switch it is? I’m sure If I look it over I can figure it out but sometimes pictures help

 

[Tinkerer]

#18.
https://www.mycnhistore.com/us/en/c...embly/cn/7C9A7D55-8FBF-E111-9FCE-005056875BD6

 

[Swampman711]

Thank you, I disconnect both connectors that went to it and still the same, maybe next step would be rebuilding the spool?

 

[Tinkerer]

Carefully check the shift linkage for worn eye-bolts and pins. Also the determine if the shift lever puts the spool all the way in the forward position and keeps it there.
#34 may be loose as goose from wear.

 

[Swampman711]

I will definitely double check that, while I’m on this forum talking about backhoes do you know if it is possible to have a hydraulic rod re tapped? The number 19 bolt must have got loose and stripped about 3/4 on an inch or threads out of the shaft wondering if it is repairable or if i need to start looking for a new rod

 

[jimg984]

yes, a machine shop can do it on lath

 

[Tinkerer]

Swampman ; If you need the service manual send me your email address in a PM.

I don't know of any way to repair it other than drilling the rod deeper and extending the threads.
That creates the problem of finding a longer bolt that could withstand the torque required to tighten it to specs.
Best option is to have a machine shop make a new rod and get a new bolt for it. IMHO.
I think the last rod I had made was $400.00. They made the rod and installed the gland on it and reassembled the rest of the cylinder.

 

[Swampman711]

Swampman ; If you need the service manual send me your email address in a PM.

I don't know of any way to repair it other than drilling the rod deeper and extending the threads.
That creates the problem of finding a longer bolt that could withstand the torque required to tighten it to specs.
Best option is to have a machine shop make a new rod and get a new bolt for it. IMHO.
I think the last rod I had made was $400.00. They made the rod and installed the gland on it and reassembled the rest of the cylinder.

thanks I got ahold of a guy that’s going to take a look at the cylinder I already have it removed from the machine and taken apart he said he may drill Draper and try to find a longer bolt, but worse case he said he can get a new rod and weld the gland back on, I’m trying to work on a small budget for the project atleast until I know I can drive it forward lol after that I will work towards doing some small fixer ups to it, and I sent you a pm also thank you!

 

[Swampman711]

Hey just an update for anyone that may have a similar problem, with the air line being ripped out and my brake pedal seems to be pretty stiff I found my problem with going forward lies some where in the brake system. If I start the machine and put it into drive right away I can move until it builds air pressure then boom it activates the clutch cut out, if I shut it off let it bleed off and go again I can drive it no problem, for a temporary trial I took out the valve stem and I can drive all day no problems other than no brakes. Hope this helps some one down the road having the same issue. Also got the hydraulic cylinder rebuilt and back on the machine, hoses need some work but baby steps! For 3500 bucks I planned on doing some TLC! Thanks for all the help

 

[Tinkerer]

The brake pedal is what activates the clutch cut-out.
Flip the switch lever (#2) to block the pedal from activating the clutch cut-out.
That 7 ton beast really should have brakes that function.

.

 

[Swampman711]

I’m definitely fixing the brakes I just wanted to make sure I could drive forward before putting to much money into it, looks like they have newer brake chambers I think I just need to fix a line that was ripped off and maybe rebuild the valve under the pedals

 

[Tinkerer]

The same treadle valves and brake chambers are used in the trucking industry.
NAPA usually has them in stock.
Drive the pivot pin out of the foot pedal to get easy access to the treadle valve mounting bolts.
In an emergency cage bolts can be inserted in the brake chambers to release the brakes.
I always use cheap pre-made 1/4 inch hydraulic hoses for air lines.
Resist the temptation to use the transmission as a brake, especially when changing travel directions.

 

[Kemper]

Hey have a case 680k and removed the pump with the trans filter on it as it was leaking due to previous owner crappy repair, helping a neighbour and cannot get the unit to go forward or reverse will some times move forward and reverse but now nothing