20kw Onan genset emergency stop breaker trips

[windy-i]

After replacing the starter in my 20kw Onan genset (MDL4) The emergency stop breaker trips. Sometimes it won't trip until the engine starts. Replacing the breaker and the Start'/Stop switch didn't fix the problem. The 2 solenoids appear to be working. What else should I test?

[GJH]

PM or email me with your e-mail or post it here and I can send you a manual on pdf. Could be any number of things. Can't figure out how to attach it here, uploading doesn't seem to work.

[windy-i]

GJH

Thanks for the reply. I have a copy of the manual. I was hoping someone had a similar problem and could point me in a new direction. The generator was working until I installed a new starter. I've checked the wiring and it's the same as its mate which works fine. I've had the starter rechecked and it's working correctly. When the starter spins (prior to the breaker tripping) it cranks the engine at the appropriate speed. I've checked the voltage (it's a 32 vdc genset) at the injector pump and don't get a consistent reading. I think it's supposed to be 32 vdc when the engine is running and 0 when it's stopped. Something is causing the voltage to go to zero and then the breaker trips.

[dottieshusband]

Sounds like a short to ground. I have a mdl4 as well, but it's operating on a 24v starter. Where did you find a 32v starter for a mdl4?

[dottieshusband]

Also on mine, there are 2 breakers that will kill the unit. The red rocker emergency stop, and a push in/pop out breaker near the hours meter. I have had occasion when that breaker tripped, but did not pop out. Tapping around it with the blunt end of a screw driver got it to pop out for reset.

[SKYCHENEY]

I still have the whole electrical box off of my old 20KW Onan. It worked fine when I retired her. The engine is now in an old skid steer loader, but the 32v controls are available, if needed.

[windy-i]

Sounds like a short to ground. I have a mdl4 as well, but it's operating on a 24v starter. Where did you find a 32v starter for a mdl4?

The starter is actually a 24v which spins too fast at 32vdc and chewed the teeth off the flywheel. I was able to find a new gear for the flywheel only to have the starter start chewing these gears. I had the starter rewound to 12 vdc but left the solenoid and everything else on the genset at 32 vdc. This works great. The start engages without chewing the gears. It works so well that I decided to convert my other genset (a mdl4) to a 12 v starter. Then my troubles began. The setup on both gensets is identical and the one with the problem was running before the conversion.

[windy-i]

I still have the whole electrical box off of my old 20KW Onan. It worked fine when I retired her. The engine is now in an old skid steer loader, but the 32v controls are available, if needed.

How much do you want for it?

[Freestyle]

Last month I gave up on my MDL4 and replaced it.

Before that the local Onan guy changed my 24v starter that was running off of the 32v batteries to a 24 supply. That started a daisy chain of troubles. First the glow plugs quit working from the lower voltage. Then the circuit boards gave out because of the lower voltage. After those were fixed it seemed like a constant battle with sensors that kept shutting it down.

So there is a MDL4 at Sun Marine in Fort Lauderdale with a new starter, circuit boards, glow plugs, injector pump and fresh water kit if anyone wants some or all of this.

Bruce
Freestyle
1985 67 CPMY
Tampa

[SKYCHENEY]

How much do you want for it?

PM sent