Koehler genset - dismatle casing to get to SCR box?

[KajLehtinen]

Hi!

Our Koehler genset doesnt runt very well. Or more correctly it runs well for 15 seconds then shuts down & repeats that for a total of three times before stopping with Over Crank (OC) as code.



By reading the manual and service manual it can be a heap of things, but when we check the output of the genset its about 298 volt (measured on P11/P44) - So I'm guessing its the SCR unit that needs attention / replacing. However when the unit starts and shuts down again it never complains about over voltage just that it stops due to OC.

I've started to tear apart the housing and I think I know that the SCR unit is in the black cabinett behind the ADC panel, opening up the side of the genset reveals a black plate with vent holes in it, tried unscrewing all the screws to the plate, but I cant still get the plate out of there.



Any ideas how to get to the SCR box to have it tested/replaced? We've had the error for the last two years, but never needed the genset so haven't put any effort into solving it until now.

I've noticed last couple of times that I've test started it (started last year) that the unit doesn't start when throwing the switch to the RUN position, but when in AUTO mode then it starts fine from the helm. The switch is fine, I've measured it. Might it mean that the ADC 2100 panel is broken since its my understanding that the ADC together with the SCR sets the voltage?

Tried pulling the LOP cable to see if that was the case why it stops - wasnt that.

/Kaj

 

[kashurst]

I had an 11Kw Koehler gennie that exhibited a great many faults. They are extremely susceptible to fuel flow issues and in my experience this can create all sorts of inexplicable fault codes including over crank, under crank, low voltage, high voltage etc etc. Also the fuel lift pump is cr@p which really doesn't help. If you haven't already done so, take the lift pump off and take it apart - there is a plastic fitting inside the metal impeller that breaks up and the pump starts to fail. Have a look at that first - if it's gone/broken/missing you need a new pump @ £100 from memory. The plastic bit dissolves in diesel- genius! (there are no spare parts - in an emergency I once used metal loaded epoxy to make a new plastic bit). Then replace EVERY fuel filter in line with the gennie.

Also release the big connector to the ECU, spray with contact cleaner and refit/release a few times to remove any corrosion, then do the three inline fuses in the wiring harness near the Air filter. Go over the generator and check for poor connections/loose crimp connectors etc. Crank the engine and bleed it, hopefully it will run.

The SCR is almost certainly OK, however if you really need to get it out, the case does eventually come apart once you remove every single self taper/screw etc. Start at the top and work your way down. Note some of the screws go into captive nuts that are riveted to the aluminium frame, corrode and come loose and just go round and round so you will need a pair of molegrips too.

Regarding the control issues - check out the multipin connector on the rear of the gennie. It's not water resistant and they corrode. On mine, owing to poor design it wouldn't click fully home and the connections would slowly come apart. A mod to the case solved that.

 

[volvopaul]

I had an 11Kw Koehler gennie that exhibited a great many faults. They are extremely susceptible to fuel flow issues and in my experience this can create all sorts of inexplicable fault codes including over crank, under crank, low voltage, high voltage etc etc. Also the fuel lift pump is cr@p which really doesn't help. If you haven't already done so, take the lift pump off and take it apart - there is a plastic fitting inside the metal impeller that breaks up and the pump starts to fail. Have a look at that first - if it's gone/broken/missing you need a new pump @ £100 from memory. The plastic bit dissolves in diesel- genius! (there are no spare parts - in an emergency I once used metal loaded epoxy to make a new plastic bit). Then replace EVERY fuel filter in line with the gennie.

Also release the big connector to the ECU, spray with contact cleaner and refit/release a few times to remove any corrosion, then do the three inline fuses in the wiring harness near the Air filter. Go over the generator and check for poor connections/loose crimp connectors etc. Crank the engine and bleed it, hopefully it will run.

The SCR is almost certainly OK, however if you really need to get it out, the case does eventually come apart once you remove every single self taper/screw etc. Start at the top and work your way down. Note some of the screws go into captive nuts that are riveted to the aluminium frame, corrode and come loose and just go round and round so you will need a pair of molegrips too.

Regarding the control issues - check out the multipin connector on the rear of the gennie. It's not water resistant and they corrode. On mine, owing to poor design it wouldn't click fully home and the connections would slowly come apart. A mod to the case solved that.

Kevin I remember trying to make a new plastic bit after servicing the set then it wouldn’t start , very frustrating.

 

[KajLehtinen]

They are extremely susceptible to fuel flow issues and in my experience this can create all sorts of inexplicable fault codes including over crank, under crank, low voltage, high voltage etc etc. Also the fuel lift pump is cr@p which really doesn't help. If you haven't already done so, take the lift pump off and take it apart

If you look/listen to the youtube clip, my feeling is that the unit runs fine since its consistent RPM's but that some logic switches it of after exactly 15 seconds. According to the service manual there is a couple of triggers that start after the unit has run for 10 seconds and has a 'trigger' window of 5 sec, which results in shutdown after 15 seconds.

Have taken apart all the connectors to the ADC, but will work it with contact cleaner. There is a lot of corrosion on the main 12volt connection points into the unit so those I need to replace/clean up.

But the fact that it runs consistent RPM's and outputs 298 volts (without any load attached) make me think the SCR unit. Wouldnt the RPM's be fluctuating if there was a fuel problem - and it does the 3 starts 15/15/15 without a hitch when starting in auto mode and hitting the start at the helm.

The SCR is almost certainly OK, however if you really need to get it out, the case does eventually come apart once you remove every single self taper/screw etc. Start at the top and work your way down. Note some of the screws go into captive nuts that are riveted to the aluminium frame, corrode and come loose and just go round and round so you will need a pair of molegrips too.

Are you saying that the black panel should come out without removing the white framing from the sound insulating box as seen in the picture? Read somewhere online that some bloke changed his SCR and it was a 1 hour job .... I've been at it more than 1 hours to say the least.

/Kaj

 

[kashurst]

Hi
I listened to the. Video, I would still check out the fuel pump. Like I said they can be tricky. Also call Atlantis marine in the UK they helped me a lot when my generator played up.
Regarding the case, it's been a while but I remember removing the control panel first, then the black metal covers under the top cover, then I think it got easier. It took me more than an hour it's not obvious.