MEP 803a failure

[EFR]

Greetings:

I suffered a failure with my MEP 803a during storm Isiais. I bought the unit two years ago with 82 hrs. Changed all fluids when I bought it, replaced leaking fuel lines, and have been running generator under light loads every 3 months. I have the unit wired to the main panel via a manual transfer switch (I hired the local electrical inspector, who is also the local trade school electrical instructor to do it right). The unit worked great for 8 hrs, then failed. I was at work (of course) when the machine stopped producing electricity, and engine starting producing thick black smoke. My wife shut off machine within 2 minutes. When I got home, I checked machine, and two hours later, there was a burning smell. I started the motor, which started fine, but load when directly to 130%, maxed out, with no electricity being produced.

I had a friend come by today and take a look at it (active duty Airforce engine mechanic). He stated electronics were fine, but the generator itself had failed.

As expected, I'm pretty frustrated. Lot of money for 8 hrs of use (crank seal has leak too I found out). I have the manuals (and all the downloads from here and Green Mountain Generator). but I think this job will be above my skill level. Any idea where a rebuilt genrator head can be found? Is there a direct Onan or commerical replacement? Do you believe commercial generator repair would be a viable option?

Thanks for any help.

 

[Mr4btTahoe]

Need to tear into it and see why it failed. You can still find new stators from time to time. Keep an eye on eBay and such.

Sent from my moto x4 using Tapatalk

 

[nextalcupfan]

Did you have the Quad winding fuse and varistor mod on the unit?
If you didn't maybe you just fried the voltage regulator and quad windings.

A member on here makes a direct replacement VR that works with fried windings

 

[BobbyT]

@kloppk has the replacement VR's that are great. I just added one to an 802 i'm refurbishing that fixed my issues.

 

[nextalcupfan]

Yes that's the one, I'm planning on replacing my original with his just for peace of mind.

 

[Light in the Dark]

That sucks. You are going to have to disassemble most of the machine to 'easily' repair this.

 

[nextalcupfan]

If the stator itself is undamaged then he should just be able to replace the regulator with kloppk's.
Granted right now we have no idea what's actually wrong with the set other than it won't make power.

 

[Light in the Dark]

I am thinking we have a mechanical issue if it was belching black smoke, so who knows.

 

[Dieselmeister]

but load when directly to 130%, maxed out, with no electricity being produced.

This sounds suspicious. Did the meter read 130% with the output contactor open or closed? The current transformer that measures this is located in the generator output wiring. This would indicate that the generator was producing power, but feeding an overload or short circuit. I would pull the top off the machine, and inspect all the wiring for a short. Hopefully the "smell" came from shorted wires, not the generator itself. The black smoke sort of confirms the severe overload.

 

[nextalcupfan]

I was wondering if something shorted as well

 

[EFR]

Did you have the Quad winding fuse and varistor mod on the unit?
If you didn't maybe you just fried the voltage regulator and quad windings.

A member on here makes a direct replacement VR that works with fried windings

No. Factory as it came from the Pennsylvania depot

 

[EFR]

I am thinking we have a mechanical issue if it was belching black smoke, so who knows.

I think I have a mechanical issue, but with the generator, not the motor. I think the black smoke was the diesel laboring under a heavy load. I have started the engine twice since. The motor starts and runs fine, but the load rating shows 130%, whether the battle short is open or closed.

 

[EFR]

This sounds suspicious. Did the meter read 130% with the output contactor open or closed? The current transformer that measures this is located in the generator output wiring. This would indicate that the generator was producing power, but feeding an overload or short circuit. I would pull the top off the machine, and inspect all the wiring for a short. Hopefully the "smell" came from shorted wires, not the generator itself. The black smoke sort of confirms the severe overload.

Both. When the battle short was open or closed, no electicity was produced, and meter stayed pegged to max. Meter worked fine before failure. In fact, whole house running, including electric stove and well was only 55%-one of the reasons why I bought this machine.

 

[nextalcupfan]

If you have access to a bolt/ohm meter check and see if you have a direct short to the chassis from the load terminals (L1, L2, L3)

Genset not running and no wires hooked to the output.

 

[Dieselmeister]

Both. When the battle short was open or closed, no electicity was produced, and meter stayed pegged to max. Meter worked fine before failure. In fact, whole house running, including electric stove and well was only 55%-one of the reasons why I bought this machine.

The 133% is telling me that the generator is producing power when it's running, but it's going somewhere else. I would definitely pull the top off the machine, and inspect the wires between the generator the voltage selector switch (the big switch behind the back panel), and contactor. Look at sheet 4 of the attached condensed wiring diagram.

 

[EFR]

Thank you very much. I'll try to get to it at night this week

 

[Dieselmeister]

On an aside, did you see any smoke coming from behind any panels, or from the generator itself while running, or only from the engine exhaust? This is a lot of current going somewhere, and something is severely overheating with this much power. Also, don't run the generator. In case it is a external short, it is repairable. If the generator itself gets toasted, that is about $1k for a rewind.

 

[Light in the Dark]

I think I have a mechanical issue, but with the generator, not the motor. I think the black smoke was the diesel laboring under a heavy load. I have started the engine twice since. The motor starts and runs fine, but the load rating shows 130%, whether the battle short is open or closed.

Correct, that's what I think. With the genhead, sorry for not being clearer.

 

[EFR]

On an aside, did you see any smoke coming from behind any panels, or from the generator itself while running, or only from the engine exhaust? This is a lot of current going somewhere, and something is severely overheating with this much power. Also, don't run the generator. In case it is a external short, it is repairable. If the generator itself gets toasted, that is about $1k for a rewind.

I was at work when it failed. My wife was home alone. Generator power went out and she thought it may have run out of fuel. She saw it smoking badly and hit emergency shutoff. When I came home at 0200, I could still smell something had burnt. I can't see anything anywhere that had burned, but I have not taken machine apart. I'm unsure how far I want to take it down. If I knew what part failed, I'm sure I could replace it. My problem is I don't know what failed yet.

 

[Guyfang]

Pull the top cover. Look for hot parts and burnt parts, When you turn off the set, will the meter stay at 130%, or drop. Do you have 120 volts AC at the 120 volt outlet?