[dennisk]

I was wondering if anybody had a cutaway/flow diagram of the main hydraulic valve on a 7720 combine. Looking at items involved that would cause the reel lift side to leak off. Thanks!

 

[aussie farmer]

looking in the parts manual there is no cut away . but does show all the internals. looking at the valve if your going to open it up you might as well put a seal kit in it .
The valves are metal to metal so they should never fail or bypass. there is a relief valve which could have crap holding it open but that should affect both services.
buggered o rings could be the problem but more likely dirt.
If cylinders have air in them would also appear to creep down.
Would need your serial number to post a pic of the right valve as there are multiple variants.

 

[dennisk]

Thanks for your reply! I removed one poppet and saw no wear, so the leak is occurring at another poppet or seat o-ring in the circuit. You have good advice regarding the seal kit.....I was hoping to quick drop in a new poppet or seat/o-ring assembly and leave the rest alone. Thanks again!

 

[Duane H]

Is one cylinder leaking down if so you need a seal kit in the opposite one

 

[dennisk]

The leak down occurs with the variable speed feeder house hooked up.....a grain head is not used. There are no external leaks on the variable speed sheave assembly.

 

[michaelshawn]

Duane H is right, your problem is an internal leak in the other cylinder.

MS