C-160 Hydro causes RPM drop under load

[Gary S Minnesota 62]

Hi Folks,

 

I picked up a nice 1997 C-160 and finally have it purring nicely.

My question regards the Sundstrand hydro unit.  It seems to have plenty of lifting power, easily raising the two stage snow thrower that is currently mounted.  What puzzles me is that the engine RPM drops a bit when the lift is engaged and remains at the lower RPM as long as the snow-thrower is is in the raised position.  Once the snow thrower is lowered the  engine RPM goes back up.  Is this normal for the Sundstrand unit?

My 520 H with the Eaton 1100 also looses a bit of RPM when lifting but as soon as the up lever is released the RPM returns to normal even though the load remains in the up position.  Just curious!

Thanks, Gary

[pfrederi 20,961]

When the lift cylinder reaches the end of the stoke you hear an increase in hydro pump noise.  is that the noise what you are hearing, if so your control valve may not be returning to bypass when you release the lever...If you briefly push it towards down does the noise stop.