Do you have plenty of oil in the tank when it gets up that high? Sometimes if theirs only an inch or so over the pump and motor when it's at the top the suction from the pump and the oil bypassing in the tank causes turbulence and the pump can suck air causing it to bounce. I'm not sure packings would be next on my list. The tight packings I've had usually cause a hard initial up start or a bounce in the down level or a really abrupt down start. Have you tried putting it down on the springs to resync the pistons? And you can try some maxton or cat hydro oil additive too I you think it might still be packing related. It's cheaper then doing a packing if the customer doesn't want to pay.. hopefully something here helps
Does it bounce while on inspect running up as well? I have one that does..plenty of oil. Might add some slick to the tanks as mentioned above. I hate these things. Next step I guess is the air bladder then Bucher valve.
I think the filter was plugged. I thought that they’re there to keep the oil smell from the hoistway and the tanks are bolted and gasketed so water can’t enter the tank (just my thoughts). I think the tank size is supposed to be adequate for the amount of air needed, but it seems like even some conventional machine room tanks seem to oil can from not enough air. I just wanted to add a problem that I had seen to the original post about bouncing in the up direction.
