Doosan (& Daewoo) GC25S-3:
trouble no power steering

i have a 1998 daewoo gc25 s-3 , when i bought it it had power steering , but seemed like it had air in the system because it would steer , pretty good then , steering got harder to turn , i noticed the hydraulic tank on side of truck the tank was 190 degrees , so i opened the hydraulic tank and the filters seemed clean , someone told me there must be a blockage somewhere, so i took to forklift to repair shop they put in a new orbital , still no steering , so they rebuilt the hydraulic master cylinder , still no steering , then they put new hydaulic pump on the truck , still no steering , they checked pressure at the orbital but only went up to about 5 psi , then they took the gauge off and started it fluid shot out , but no pressure , anyone else ever have this problem on this model daewoo , we dont know what else to try to fix the steering on this unit , if you lift the back of the forklift up the steering can be turned side to side , by moving the wheels back and forth by hand, any help would be greatly appreciated thank you , serial numbe is 95-00658
  • Posted 16 Dec 2022 07:42
  • Modified 16 Dec 2022 07:51 by poster
  • Discussion started by jtt81968
  • New Jersey, United States
Showing items 1 - 3 of 3 results.
Check your email! Happy Holidays!

LS is the load sensing line, coming from the orbitrol, wich actuates the priority valve on the pump.
  • Posted 23 Dec 2022 19:14
  • Reply by Speedfreak
  • Niederlande, Netherlands
thank you for your advice , but what is a ls the Ls line , is that the low side meaning low pressure side thanks and happy holidays to you
  • Posted 23 Dec 2022 11:44
  • Reply by jtt81968
  • New Jersey, United States
Priority valve, mounted on the engine driven hydraulic oil pump.
P/N D516514
It's being controlled by the LS line coming from the orbitrol.
Worth checking if it's not blocked between orbitrol and priority valve (could be a steel line-not sure, it's been awhile since i've worked on those)

The orbitrol acts like a small pump, therefore-with drive wheels off ground_ it will deliver enough oil to steer, could be the PSI that was measured.

Pump is easily tested; when the lifting works pump is fine, the priority valve could be stuck or not getting an LS signal from teh orbitrol.
Normally a visual check of the PV is done by lifting at a steady speed, when steering the lifting motion should be decreased during steering.

Good luck!
  • Posted 21 Dec 2022 01:03
  • Reply by Speedfreak
  • Niederlande, Netherlands

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