# Hydraulic problems with Case 770



## bfeldh (Jul 13, 2010)

I have a 1970 Case 770 with a front end loader and can't get the loader to pick up big bales of hay. I have suspected the loader wasn't quite normal for some time. The loader works fine on light loads, but won't even try to lift a heavy load. The arms want to creep down at times but not consistently like I would expect if the seals in the lift arms were bad. I replaced the seals in the lift arms a few years ago and put on a different hydraulic pump last year when I had the power shift overhauled. I suspect problems with the control valve or the relief value. I put a pressure gauge in line the lift cylinders and it read almost 1400 psi when the cylinder was fully extended so I think that means the pump is okay and the relief valve is okay. I read on the internet that the control valve has some thermal relief valves that go bad. I don't know where to start. Anybody got any ideas. Thanks


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## Hoodoo Valley (Nov 14, 2006)

Welcome to the forum! Could it be that the capacity is less than you expect? ie, the loader isn't intended to pick up that much weight?


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## lsmurphy (Sep 12, 2008)

bfeldh said:


> I have a 1970 Case 770 with a front end loader and can't get the loader to pick up big bales of hay. I have suspected the loader wasn't quite normal for some time. The loader works fine on light loads, but won't even try to lift a heavy load. The arms want to creep down at times but not consistently like I would expect if the seals in the lift arms were bad. I replaced the seals in the lift arms a few years ago and put on a different hydraulic pump last year when I had the power shift overhauled. I suspect problems with the control valve or the relief value. I put a pressure gauge in line the lift cylinders and it read almost 1400 psi when the cylinder was fully extended so I think that means the pump is okay and the relief valve is okay. I read on the internet that the* control valve has some thermal relief valves that go bad.* I don't know where to start. Anybody got any ideas. Thanks


 

Or the spools need rebuilt, you could be getting a lot a bleed-by also.

If you are shure it's not the pump or relief.....

You know also the cylinders may be bleeding by...

Scott


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## Hoodoo Valley (Nov 14, 2006)

lsmurphy said:


> Or the spools need rebuilt, you could be getting a lot a bleed-by also.
> 
> If you are shure it's not the pump or relief.....
> 
> ...


Could check for this, by seeing how long the loader stayed elevated before coming down, could you?


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## lsmurphy (Sep 12, 2008)

tractor beam said:


> Could check for this, by seeing how long the loader stayed elevated before coming down, could you?


 

Yeah, if the valve is bad, spool or relief, it will leak down. Assuming there are no other leaks.


Probably the valve as he suspects.

Scott


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## Yeggster (May 22, 2010)

I also suspect control valve spool leakage ...

I just redid the hydraulic hoses and control valves on my old case, before the re-fit it had very low power, could not lift it's own wheel off the ground, even at full throttle.

After the re-fit it pops the front wheel off the ground at idle.


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