Doosan (& Daewoo) G25E-3:
Transmission slipping

Having transmission problem with daewoo G25E-3 KP0774 transmission works great when cold but slips in forward and reverse when warm. Clutch pressure drops to 35 psi when warm. Transmission was rebuilt a year or so ago. Have been through control valve but no change. Acts like a relief valve sticking to me since problem is in both directions, inching spool seems to be returning fully. Anybody run in to this problem before?
  • Posted 2 Apr 2015 10:33
  • Discussion started by terry_c
  • Oregon, United States
Showing items 1 - 8 of 8 results.
Hi can you help me, have the same problem I already chance all the springs on the valve head pressure is ok but is not going reverse you have to speed up to get the gear working.
  • Posted 18 Sep 2019 09:33
  • Reply by Joe_Campos
  • Guatemala
Check the pressures as stated in an earlier post. This will help you isolate the problem between the transmission internal parts and the valve body on top of the transmission.
  • Posted 22 Dec 2015 06:17
  • Reply by IFD45
  • Wisconsin, United States
Today i also replaced that plastic orifice screen,
Slight diffrence observed in cold but when transmission reached at opreating temperature its start slipping in reverse. Too much acceleration required to move lifter in reverse.
  • Posted 18 Dec 2015 03:43
  • Reply by sauleh_a
  • bgfjvufgvbfg, Pakistan
Check to see if the pressure on the reverse clutch pack test port on the valve body is between 105-125 psi at idle and 105-140 psi at 2000 RPMs. The link below shows this on book page 45 and 46.

If you have good pressure there is a possibility that the piston return spring in the reverse clutch is not made correctly. The spring will compress all the way it is allowed to and not allowing the clutch pack to tighten up. Daewoo sent us new springs that were not made correctly. We ended up having the springs custom made. Daewoo never got back to us admitting there was a problem with there replacement springs.
  • Posted 12 Dec 2015 08:47
  • Modified 19 Dec 2015 22:31 by poster
  • Reply by IFD45
  • Wisconsin, United States
I am facing slipping trouble but only in reverse, both conditions hot /cold
2 times transmission opened up but problem is still,
I replace quad rings, friction discs, but didnt change metal rings because its look good and scratch less. Same parts replaced in forward pack also, which is working correctly.
I also found that orifice plug which you discussed above, partially broken and its thread has been slipped. But i didnt change because that part is not available at dealer.
I also checked it at another daewoo truck by removing this orifice plug and didnt found any change.
Please help.
  • Posted 10 Dec 2015 01:58
  • Reply by sauleh_a
  • bgfjvufgvbfg, Pakistan
Here is some more info from one of my previous posts about transmissions slipping.

You could also check the modulating valve orifice plug. This can loosen and causes slipping mostly when hot. Although you would most likely notice this in forward and reverse. Remove the plug on the valve body that you can stick a 14mm hex bit in (side of valve body closest to torque converter). I have my bit cut to about 30mm and use a 14 mm wrench to remove plug. Then remove a spool with a snap ring pliers or something similar. On the back side of the spool is the plastic modulating orifice plug (usually red in color). Check to see that it is tight.

If the transmission was rebuilt in the last seven to eight years it could have some defective quad rings on the clutch pistons. The rings were made of a material that could not withstand the heat and would get hard and brittle. This could happen in a matter of a couple thousand hours on the truck, if it has been ran hard. Daewoo never did say they could have had incorrect material for the rings. This probably happened to at least 10 transmissions where I work.
  • Posted 10 Sep 2015 03:03
  • Reply by IFD45
  • Wisconsin, United States
Common symptom with -3 Daewoos.
Facing the engine there is a transmission valve body plug. requires a stubby or cut off 9/16or 14mm hex driver to remove.
Once the plug is out you will notice a valve with a small plastic filter fitting which must be screwed back in if loose..
Try this first.
  • Posted 13 Aug 2015 03:22
  • Reply by tom_p
  • Alberta, Canada
May need to change the oil
  • Posted 26 May 2015 09:24
  • Reply by edward_m
  • Texas, United States

Having trouble using the Discussion Forums? Contact us for help. accepts no responsibility for forum content and requires forum participants to adhere to the rules. Click here for more information.

Hangcha CBD15
Used - Sale
Toyota 8FGU32
Flesherton, Ontario, Canada
Used - Sale
Fact of the week
Pilots and co-pilots are required to eat different meals just in case one meal causes food poisoning.
Global Industry News
edition #1168 - 29 February 2024
Hydrogen fuel cells are in the news again this week, with an unnamed American car maker choosing the fuel source to run the materials handling fleet at a new manufacturing plant... Continue reading