I have a zd 21 that is running fine but recently the hydraulic deck won't raise after the mower is warmed up. I've done a google search and found two other people who had the same problem but there was never any follow up about what the problem was and how much it should cost to fix.
I'm scheduled to take the mower into the dealer Wed.
I'd still like to fix this myself. Or at least know what is going on before I take it in.
How many hours are on this mower?
The hydraulic system must be working or it would not be moving... so it would seem it will be:
1. Hydraulic cylinder..
2. Control valve...
3. Hydraulic oil has sheared down to the point it will not lift deck...
I would suspect , #! or #2...
There is also a chance that the lever for the lift is not actuating the control valve... :smile:KennyV
How many hours are on this mower?
The hydraulic system must be working or it would not be moving... so it would seem it will be:
1. Hydraulic cylinder..
2. Control valve...
3. Hydraulic oil has sheared down to the point it will not lift deck...
I would suspect , #! or #2...
There is also a chance that the lever for the lift is not actuating the control valve... :smile:KennyV
The lift control may have a bypass valve spring that has weakened...
I'll be curious as to what they find...
Please post back, hydraulics are interesting to keep up with... :smile:KennyV
Something came apart in the hydraulic system sending a shower of metal shavings. Because it was still moving well, they cleaned out the system and replaced the precharge pump. This fixed it for 4 hours. They then replaced both the hydraulic motors and the precharge pump and I had them install a hydraulic reserve tank.
It really hurt the wallet but I've used it for about 10 hours now and it is still functioning normally.
Hmmmm ... well I guess that makes good sense as the charge pump is generally used for the auxiliary hydraulic functions...
A failure that diminished it's output pressure would not show in the drive pumps as long as the charge pump could keep up the GPM...
A reservoir is always a great help to any hydraulic system, mainly for heat removal but also as a place to allow contaminants to settle out of the otherwise high velocity oil flow....
Metal pieces pushed into the drive motors is not good... I have always used internal and external magnets on the hydraulic filters on most of my hydraulic drives... of course the filters are at the end of the system and what ever gets trapped there has already passed through pumps & motors.... :smile:KennyV
My father has a ZD28 Pro. Something happened in the hydraulic system when it has less than 100 hours on it. The left wheel motor started slowing down to the point it would stop after about an hour of mowing. The dealership replaced the entire system under warranty. Basically, if it had hydraulic oil in it, then it was replaced. That was a few years ago.
Something came apart in the hydraulic system sending a shower of metal shavings. Because it was still moving well, they cleaned out the system and replaced the precharge pump. This fixed it for 4 hours. They then replaced both the hydraulic motors and the precharge pump and I had them install a hydraulic reserve tank.
It really hurt the wallet but I've used it for about 10 hours now and it is still functioning normally.
This is my first day on this forum. I searched for just such a forum so I could ask the same question: "why does my deck not lift after the system is warmed up?" I'm sorry now for seeking an answer.
I will drop my ZD21 off at the dealership after this mowing season ends for routine end-of-season maintenance, and will point out the deck-lift problem. I hope I get off lighter than you did. This is the only thing that has never worked perfectly on my mower, which I bought new in 2002. It now has about 600 hours on it.
If everything else in my life ran as dependably, cheaply, and effectively as my Kubota mower and my Kubota RTV 900, my life would be just about perfect.
