L785 hydraulics question

[jj112]

I have a 1984 L785 with a Ford diesel engine. The machine has developed several hydraulic leaks recently. I jacked up the machine and put it on wooden cross beams, took off the tires and ran it with the seat assembly off to look at the pumps and motors while it was runniing and under load. Here is what I found: The small hydraulic pump on the end that supplies power to the boom system leaks when under load from the bottom, I can't see where this leak is coming from. The pump works fine but leaks. Any ideas what might be leaking? Both of the controls on top where the steering control levers operate have leaks at the shafts I think they are called servos? Can these have new seals installed in the shafts? The drivers side steering motor leaks from the bottom when under load. Any ideas? I also have to replace the CV joint between the engine and the pump assembly, any idea as to the easiest way to replace this? Thanks, JJ

 

[Tazza]

Hopefully the pump leak is simply an O ring. The pump leaks where the controls go should be pretty easy to do, they should be a shaft seal that you knock in.

 

[shelby]

.....Hi For years we had a L775 with a Deutz diesel I think the 785 was quite similar....we cracked the pump housing, and had to change the pump, the reason the pump cracked was because the relief valve stuck, so make sure the pump housing is ok.... changing u joints is always fun, once again if your design is the same, we had to remove the batterys and steering shocks, and then we literally cut the crossmember below the fuel tank, and made it removable, that gives a lot more room to work on things....between the fuel and hydraulic tank, and that bloody cross member, and the fact that you have to stand on your head to work on it(its great fun) another tip, keep tabs on your oil level in that three way gearbox that the pump drives from, it does not hold much, and if you have a seal failure, it can burn that gear box up quick. We have an 865 now, the hydraulic system calls for 5-30.....I was running a mixture of 5-30 and hydraulic oil in the 775, that seemed to quiet the pumps down a bit, of course we had 7000 plus hours on it, so the pumps were quite wore.....good luck to you...S

 

[shelby]

I just wanted to add this. In our 775, we contemplated replacing the pumps and motors, it was just such a good machine, especially with the Deutz engine, but when it was all said and done, it was going to cost about $12000.oo per side to replace everything, and the final drive chaincases were completely wore out too.......the Deutz had enough power, that it was really hard on the chains, we were adjusting tension constantly, where as the gaspowered models, never had those type of problems, our machine had some of those same leaks too, they were not real bad, and we just sort of accepted them, we had a leak on the hydraulic tank, it had a bolted cover, and those bolts were forever coming loose, we had more trouble with that than anything else, when it came to leaks. You may want to pull your hyd pump out and check it over, check the splined shaft for wear as well, its not a very big shaft......S