620 rockershaft

[KENWORTH]

hi guys. think i may have figured out my problem on my 620. now i need a solution. the rocker shaft has not been used for quite some time. i went to install a 3 point hitch on it, as it did not come with one. i cycled it a few times and it seemed to work fine, but then the engine started to pull down and the hydro oil began to get warm. the rocker shaft arms raise no matter where i put the contol lever. i think the valve/control that controls the rockershaft postion, is stuck in the raise postion. i did remove the piston the runs up and down in the cylinder and cleaned up both. put new packing and o-ring on. i still have the same problem. any ideas? thanking you in advance. bruce

 

[DONMYEIL]

Sounds like some of the linkage inside has came apart.

 

[DONMYEIL]

The valve is on the front side of the rockshaft housing. You have to remove the rockshaft to get get to it. The rockshaft valve is pinned to the linkage with a pin and a cotter pin.There is a valve return (F2762R) spring hooked to this same pin. I wonder if yours is broke.You will have to drain the hyd. oil to see the bottom of the housing so you can find the broken spring.