Case 680K Sudden loss of all Hydraulics

[DustyShackleford]

Hey there everyone. Long time reader First time poster. I've recently ran into an issue that has me stumped.

I've got a mid 80s Case 680K construction King. Bought it about a year ago and it's been a good worker. I've been slowly updating things here and there to make her a nice machine.

On to the problem..... Here in Pennsylvania we finally are having a white winter which we haven't had in years. It's been in the 20's or lower for at least 2 weeks straight now. The other day I fired her up and noticed the steering was a little tight, felt like low fluid. Only took about 2-3 gallons. Typically when I've felt that on other machines before it's when they're low low. In any case, i topped her off, admittedly probably a little higher than i should have, but i topped her off. Fired her up and hydraulics were still a little tight. I let her run and walked away for maybe 5 mins MAX to let her warm up and get all the fluids warm. When I returned I had NOTHING and I mean NOTHING. No power steering, no hoe, no loader. Not even a wiggle. I've been playing with it for days now and haven't been able to sleuth it out. I have the full service manual and schematics. the 680k does have 2 pumps, One does the loader and one does the power steering and backhoe. I can't imagine the odds that both pumps would fail at once. Here's what I have tried so far.

- Verified correct fluid level, I even let out a little bit to make sure it was not over filled.
- removed hydraulic filter and put a bucket underneath then fired her up to verify flow. instant waterfall of oil. So I can confirm that at least one pump must be flowing.
- replaced filter with brand new one
- pulled what the main relief under the floor and cleaned it. Not sure what I'm looking at here or what to check for. I see the exploded diagram in my parts book, I guess I could fully disassemble it to inspect.

- I've tried it over a few days now and still do not even have a wiggle on any of the hydraulic functions. I really want to come up with a set troubleshooting path. the one in the service book for full loss just says to check the fluid level and relief valve.


I'm looking for any ideas or a set troubleshooting path to start following. I'm an electrician but I know my way around a wrench and I'm good at troubleshooting so all ideas are welcome.

 

[Billrog]

Splines gone on hydraulic pump sleeve?

 

[Tones]

Splines gone on hydraulic pump sleeve?

X2. That's the only common denominator.

 

[DustyShackleford]

Ok forgive my ignorance but are we talking about the splines inside the pump? Or the ones on the shaft that connects with the engine? Something that requires new pumps or pump rebuilds? I guess I should look at my parts diagrams for pump sleeve. Ha ha

 

[DustyShackleford]

one of these parts? I'd post both pumps but their diagrams are nearly identical even though they mount to different locations.

 

[Vetech63]

Those illustrations are not showing the pump drive coupler. Try looking at the breakdown for the crank drive pulley or damper area

 

[DustyShackleford]

ok thanks. Here are what I believe are the diagrams for the front and rear pump mounts. not so sure about the rear one that's off the flywheel but this diagram does show a part labeled "sleeve" in the vicinity of where it mounts. I assume 38 is the part in the front diagram? is this just a splined couple that the pump shaft slips into? is it designed to fail before the pump like a fuse?

It still begs the question, what are the odds that both pumps would wear off these splines at the exact same time?

 

[Vetech63]

If you have what I think you have, it will look like this.........

The pump is driven off the front of the engine crankshaft with the above coupler. Look at the front of your engine, under the radiator area.

 

[clueless2]

The steering and hydraulic pumps have their own filter inside the hydraulic tank.
Have you changed them or looked at them for blockage ?

 

[DustyShackleford]

Vetech, one pump is on the front of the engine the other is on the back off the flywheel.

Clueless, I did not check those screens inside the tank, not sure if I can physically get to them. But being that I get a good flow out of the main filter I’m making the correlation that at least one of them is not blocked. So if at least one circuit is flowing oil I should have at least 1/2 of my functionality right?

 

[Vetech63]

Vetech, one pump is on the front of the engine the other is on the back off the flywheel.

Clueless, I did not check those screens inside the tank, not sure if I can physically get to them. But being that I get a good flow out of the main filter I’m making the correlation that at least one of them is not blocked. So if at least one circuit is flowing oil I should have at least 1/2 of my functionality right?

Can you post.some pics of the pumps and locations

 

[clueless2]

Open the hood and you will see a round steel plate with a bolt in the center.
That is the access to the filters or screen. The 680's with a screen usually had the front mounted single hydraulic pump on the front of the engine crankshaft.
Pump the brake pedals and release all of the air pressure in the system.
Drain the tank before you loosen the plate !

 

[DustyShackleford]

I’ll take pics tomorrow night when I’m at the machine.

Clueless thanks for the info. I’ll put those on the parts list to replace/clean

 

[DustyShackleford]

ok here are some photos. The first darker pump is the pump for the loader that runs off the flywheel I believe. It’s under the footpedals behind the engine.

The second pump is the one on the front of the motor that drives the power steering and backhoe.

This photo is of the loader valve, it’s only about a 2ft hose run off of the darker rear pump. I pulled the large plug on the side and cranked the engine and fluid was instantly flowing out just cranking it without running. So I definitely have at least some flow out of that pump.

I incorrectly stated that I took out the pressure relief. None of the three caps that I ended up pulling off of this valve seems to be the pressure relief as nothing comes out behind them. (One was the quick connect for diagnostics, one was this large blank plug with nothing behind it and one was a 3/4 cap on the bottom) If someone knows where it is physically located I’m all ears.

Lastly for clueless, looks like the access for those pick up screens is behind this large circular plate on the front of the hydraulic tank. Held on by a singular center bolt. Will this have an oring or gasket I’d assume? I’d want to ensure I have that on hand before I take all that apart and down the machine further

 

[DustyShackleford]

Darn it, it threw the last photo first, sorry about that. Also hydraulic schematic for reference

 

[HarleyHappy]

Any possibility of your hydraulic fluid is full of water and your filters are frozen? I don’t really like the look of that fluid.

 

[DustyShackleford]

Harley, I thought of that as well. It hasn’t been over 20 degrees since Christmas to test that theory though. HOWEVER, the fact that it’s flowing at all tells me that wouldn’t be the case. Also the primary hydraulic filter is now brand new, so it would have to be the screens in the tank that clueless is talking about

 

[clueless2]

That water in the hydraulic oil is never going to allow that crap to flow through the screens and filter.
Not unless it is a lot warmer where it sits.
You can roll the front bucket all the way back and hold loader valve in the rollback position and run the motor about 2000 rpms to warm the oil.
Be sure you have the air pressure up before doing that.
The oil tank has to be pressurized to ensure the hydraulic pumps get a constant flow of oil.

You need to do a complete system flush before the pumps are destroyed. If they aren't already.
The tractor has to be somewhere warm before doing that.
The flushing procedure is in section 8003 page 6 of the service manual.
The plate on the tank does have an O ring. You can reuse it if looks OK.

 

[HarleyHappy]

It can be flowing but if it can’t suction it, you ain’t getting nothing.
I have a feeling, your problems are temperature related and if I’m right, you better address it before long.
I know I’m sick of my hydraulics having water in them myself.

 

[DustyShackleford]

Well unfortunately being the middle of winter here in western PA I don't think I'll have the opportunity to do any temperature dependent testing or flushes in the near future. Forecast shows teens and 20s for as far as the weather man can see. so if that's the next most agreed upon course of action then it may be a long while before I report back. Thanks again for the advice and input