New rebuilt ZD21 hydraulic pump and both drives overheating

Merd

New member

Equipment
ZD21, M9000
Aug 6, 2020
3
0
1
Kentucky
I have a 2004 zd21 with 1400 hrs on it. The left drive motor went out price was $1900 parts only. Charge pump, both drive units and add on oil reserve parts about $2600. opted for all parts. Did own work with help from a friend and repaired. New oil, filters ect... Problem first use: couple hrs mowing and charge pump was about 275 degrees hot. Does not seem good. How hot should pump and drives run? Any help or suggestions greatly appreciated.
 
Last edited:

mikester

Well-known member

Equipment
M59 TLB
Oct 21, 2017
3,125
1,607
113
Canada
www.divergentstuff.ca
You could try adding an external oil cooler. The problems you are experiencing are typical for that machine/model/years and is a Kubota design problem. Sorry for the bad news. If it was me and I was using it for commercial use I’d be trying to sell it and buy a post 2008 ZD326 or 331. It’s already sunk costs so the most practical answer is to keep on using it until it breaks down, then sell the machine as is.
 

Merd

New member

Equipment
ZD21, M9000
Aug 6, 2020
3
0
1
Kentucky
You could try adding an external oil cooler. The problems you are experiencing are typical for that machine/model/years and is a Kubota design problem. Sorry for the bad news. If it was me and I was using it for commercial use I’d be trying to sell it and buy a post 2008 ZD326 or 331. It’s already sunk costs so the most practical answer is to keep on using it until it breaks down, then sell the machine as is.
I appreciate your response, but I've had the machine for 16 years and would like to use it another 16. Spent a lot for parts and would like to make sure everything I've done is correct. Still running hot so I'm going to change filter and suction strainer again see if that helps. thanks once again
 

North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
28,286
4,852
113
Sandpoint, ID
Look at the pressure regulator portion of the setup.
 

North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
28,286
4,852
113
Sandpoint, ID
Here is the pressure relief valve:

You need the WSM to know how to test it.
ZD21 relief valve.JPG
 

lugbolt

Well-known member

Equipment
ZG127S-54
Oct 15, 2015
4,807
1,575
113
Mid, South, USA
need to get your hydraulic pressure test kit out & start digging in, and comparing to the proper WSM for your machine.

flow + pressure = heat.

Did you clean the suction screen? Did you replace all of the o-rings on the pipes? What fluid are you using? What filter are you using? Is the system fully bled and full? could there be a problem with the deck lift section?