Deck lift problems - 782

TN_Explorer · #1 07-15-2013, 11:23 PM

I have recently begun experiencing issues with my 782 -- when I start it cold, reverse is very sluggish, goes away after it has run a couple of minutes. The deck was also acting sluggish, now does not want to move up or down. The dipstick reads full when the engine is off, less when it is running. I got some HyTran and topped it up while running. This had no effect. I disconnected the deck and played with the lift lever, got it to move and then hooked the deck back on & it worked long enough to mow the lawn. When I finished mowing (about an hour), the deck lift once again doesn't work.

From what I read, my first order of business will be to get a filter and replace the oil. I'll be doing that later this week.

I suspect this won't solve the problem, as the transmission works. When I engage the lift, I can hear it load up, but nothing happens.

I did try to find some info through a search of these forums, but haven't found anything so far.

I'd be eager to hear from some of you folks as to what I need to be looking for.

Thanks,
Mike

riesedesperado6170 · #2 07-15-2013, 11:41 PM

well i can't say for sure but i think it the filter. if getting plug and starving the hydro i think it fluid goes to drive side first then split to discharge side which is your lift so it move but not pick. if that don't work check the check valves next.

J-Mech · #3 07-15-2013, 11:47 PM

Do a fluid and filter change. Then come back and let us know. I think it will fix your problem. They hydrostat recirculates the oil it uses to drive. The charge pump only supplies whatever disappears through normal internal leakage. So, a plugged filter will not affect drive, as much as the lift.

Cub Cadet 123 · #4 07-15-2013, 11:54 PM

Quote:

Originally Posted by riesedesperado6170

well i can't say for sure but i think it the filter. if getting plug and starving the hydro i think it fluid goes to drive side first then split to discharge side which is your lift so it move but not pick. if that don't work check the check valves next.

I had some of the same problems with my 782, but I had no reverse whatsoever. My problem was an easily identified problem--check valves were shot. I replaced them and fixed my problem, but as the others have already mentioned, start with the filter first and then progress to the check valves second if needed.

Cub Cadet 123

R Bedell · #5 07-16-2013, 07:32 AM

Quote:

So, a plugged filter will not affect drive, as much as the lift.

The Hydro Filter ........filters ALL oil and circuits within the Sundstrand unit.

TN_Explorer · #6 07-16-2013, 08:35 PM

Thanks - You have given me hope. I am off Friday and will plan a filter and fluid change then.

J-Mech · #7 07-16-2013, 09:03 PM

Quote:

Originally Posted by R Bedell

The Hydro Filter ........filters ALL oil and circuits within the Sundstrand unit.

This is pulled from the Sunstrand manual...

Hydrostat fluid flow.jpg

As you can see, the blue circuit is where the oil returns from the motor. It bypasses the tank, filter, charge pump and goes directly back to the main pump. The charge pump adds fluid to this circuit to account for normal fluid loss.

This system only filters the oil BEFORE the charge pump.

TN_Explorer · #8 07-18-2013, 10:45 PM

I replaced the filter and it seems as though the deck lift is working like it should. Thanks for the tip! I would never have thought the filter would have made such a difference.

Cub Cadet 123 · #9 07-21-2013, 12:41 PM

Believe it or not, it may do the exact same thing again on you soon. I have heard of people replacing the filter and the problem seems to be solved, only to have it re-occur again on them. This would happen if your hydrostatic fluid has had water in it (or its really old). The hydrostatic fluid globs or thickens when it comes in contact with water, so maybe one glob of it was clogging up your filter originally and another glob may do the same. If it happened a second time, then you might consider pulling off your rear plate, totally cleaning out all of the old fluid, replace the gasket and plate, fill with new fluid and THEN replace with a new filter. Just kind of an fyi to keep in the back of your mind.

Glad you have resolved your problem,

Cub Cadet 123

TN_Explorer · #10 08-17-2013, 11:57 PM

I did the filter change & the deck lift worked, but then it quit again shortly thereafter. Per Cub Cadet 123's note I pulled the back plate and drained all the fluid & looked inside. Everything seemed exceptionally clean, except there were tiny globules along the bottom of the case (I assume water in the fluid).

I wiped it out thoroughly, put everything back together with another new WIX filter and new Hytran Ultra.

The forward & reverse seem to work better than ever, but the deck lift doesn't even try. Moving the lever makes it sound like it's trying, but absolutely no movement.

I would really like to get this fixed, but don't want to just throw money at it.

I'd like an opinion whether to try check valves, or whether to try and pick up a used control valve and/or cylinder.

I always try to think things through and troubleshoot problems in my head before turning wrenches, but hydraulics are a little new to me.

Thanks for all the help and encouragement so far.

-- Mike