Doosan (& Daewoo) G 30 S-3:
hercules 2.7 low on power

Hoping to find some help or guidance. I have this 6000# daewoo forklift for my business. bought it a year ago and i've never been satisfied with it. hr meter is over 12k. The engine starts and runs fine, but is super slugish. It works on level surfaces but on any sort of incline it can't hardly pull its own weight.

The ignition system has had a tune up with a new cap/rotor/coil/wires/plugs and has good spark. The PVC was leaking and has been fixed. I had a specialist come by and he said our propane system was all functioning properly.

I checked Compression on all cylinders and is was roughly 106-110.

Im moving to a large warehouse here soon, and we are installing a dock ramp to go between the inside/outside, and I'm pretty sure this will never make it up the ramp, especially with a few thousand pounds on it.

Looking for any guidance as to what to look for, or where to go next. I like this forklift but the lack of power has really been a big disappointment since day 1
  • Posted 24 Mar 2017 01:08
  • Discussion started by andrew69_04
  • Colorado, United States
Showing items 1 - 6 of 6 results.
12k hrs is high for the herc engine ,that said compression should be 140 i believe , a valve job may be all you need or engine rebuild?
  • Posted 10 Sep 2020 22:40
  • Reply by stillworkin
  • New York, United States
Hello Andrew did you ever figure out the problem with this forklift?
  • Posted 5 Sep 2020 06:20
  • Reply by glenn_levit7
  • Texas, United States
Montacargas, Tequila y Limon!
Also to note, When driving any sort of distance, say a 100 yards, it really feels like you have to let out of the throttle some to get the lift to accelerate more. Applying more throttle would cause it to bog down.

We found that by removing the hose from the converter to the carb removed that bog and lets the motor rev and run better.
  • Posted 25 Mar 2017 15:58
  • Reply by andrew69_04
  • Colorado, United States
I know the tech that came out checked the trans pressures. There is no slippage. We had also checked the brake for hanging up.

The governor is something I will look at tomorrow. I have no idea what screw is the mixture adjustment but the only one i've found on the carb we can turn and it doesn't seem to make any difference in the way it runs.

Based on the compression, is that fairly normal for these engines? Seems quite low compared to any other engines i've ran tests on in our shop
  • Posted 25 Mar 2017 15:28
  • Reply by andrew69_04
  • Colorado, United States
That has a governor located under the carb and if that's broken the throttle plate in it may not be opening as it should.
  • Posted 24 Mar 2017 07:15
  • Reply by mrfixit
  • New York, United States
Could be a couple of diffrent things....could be that the carb power adjustment is out and needs readjusted.....i have seen the same issue on several trucks with your exact complaint being the carb out of adjustment......
....could be a transmission issue with pressures/slippage...would need to have a QUALIFIED forklift technician do a transmission pressure test to see if the is a issue with transmission....
......could be a brake hanging up and dragging....
...lthis is just my WAG arm chair diagnosis....and just because you have had someone look at it already,dosent mean they are correct or know what they are doing.......and just because i commented dosent mean i am correct.....
  • Posted 24 Mar 2017 03:06
  • Reply by kevin_t
  • Pennsylvania, United States

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