Seeking Onan 8MDKDB 1C service manual

[oak_box]

Does anyone know where I can get the service manual for an Onan 8MDKDB 1C generator?

It has never worked since I bought the boat. It will start, but not keep running.
I had a generator guy come out to look at it. He did something (wouldn't show or tell me what) to hold the throttle that got it to start and run, but as soon as he took his hand off, it died. He said something was telling the generator to stop...

The remote panel was disconnected by the service company that the previous owner tried. The new guy said that some generators (maybe this one, maybe not?) were set up that the generator would die without the remote panel, and needed a jumper to run without the remote panel.

Unfortunately, while the generator guy seems to know what he's doing, I haven't been able to get him to come back and work on it.

Maybe if I could get the service manual, I could at least get the remote panel hooked back up, and possibly debug the rest??

Thanks!
John

 

[Portage_Bay]

Any idea how old the gen set is? Cummins supports some of the Onan gear by no means all of it. Start at a Cummins parts dealer. If no joy and it's old enough try SmokStak. They've been a tremendous resource for me with a 7.5 MDJE

 

[MacPhid]

Check BoatDiesel as well, lots of info on the forums there.
If the generator starts but shuts down when set to run, it could be one of the limit safety switches, high exhaust temp limit, high coolant temp etc.
This link is to an MDKD manual, might be helpful
https://www.seapowermarine.com/seap...18/05/MDKDP-DR-DS-DT-DU-DV-Service-Manual.pdf

 

[BruceK]

Could relate to the fuel solenoid, the mechanic might have held the plunger across and while he did, it ran. They have a "start hold" and a "run hold". I had the reverse, if I held the plunger across to start it, it started and it ran.
So while it could be the solenoid itself, it could also be an interlock saying "something is wrong, so don`t run".
Maybe search online for a replacement fuel solenoid. Non Cummins versions(? identical anyway) are cheap by comparison and a useful spare to have to hand if it turns out more than the solenoid itself.

 

[Portage_Bay]

One simple test is to power the solenoid directly from the battery bypassing the normal engine control circuitry. If it runs the solenoid is OK. If it runs at or near the correct RPM the engine is OK. That indicates the problem is in the control circuitry. Make sure you have a way to quickly kill that connection because the stop switch won't work. Don't run it for more than a few seconds. It's running unprotected. Now the fun begins. The older Onans have a fist full of relays and switches. Finding the faulty one takes time. You'll need the service manual and schematic to make much progress. Until you have that one thing you can do is check all the connections in the control box for looseness and corrosion.

 

[Portage_Bay]

You may find your manuals here
https://www.smokstak.com/forum/threads/onan-manuals.215916/
You might have to join to access and download.

 

[oak_box]

Thank you guys!!!

The smokstak reference led to this link for Onan manuals:
http://www.skilledcrafting.com/onanfiles/

At the top of that listing is an entry for a table that provides all the manuals (operator, parts, service, etc) for each product. That table was VERY HELPFUL!! Once you knew the manual number you needed from the first table, it was easy to find the manuals (listed in sorted order by part number).

According to the survey / prior documentation, it appears my generator was installed in 1991 (even though the boat is a 1983 - so did they replace the generator, or add it later? who knows...).


The previous owner had one of the local companies come out multiple times. They replaced one or two of the limit switches (typical cause of generator not starting and continuing to run), replaced one of the solenoids (the fuel solenoid?), and replaced the main control board. They gave up at that point, and failed to reconnect the remote start wire harness.

So, I have some light reading to do over the next several evenings....

John

 

[BruceK]

The 6KW MDKD on my previous boat ran well. One day, removing the sound shield after dropping the coolant cap into it,I found the exhaust heat sensor detached. Reattached, sound shield refitted, (no mean feat considering the location), it would not start. Sensor re-detached, it ran perfectly for another 9 years. I "hand checked" the temp of the exhaust water, it wasn`t hot, defective sensor I assume.

 

[Lepke]

ebay is a good place to find old manuals. But they're not much help, especially the engine. Onan doesn't want you to fix your generator but buy a new one.
When you hold the start button, it bypasses all the safeties, low oil pressure, coolant temp, maybe exhaust temp. Usually if the engine starts but fails to continue running when the button is released, it's a failure of one of the sensors. If the stop solenoid fails, then the engine usually doesn't start at all.
There is a lever on the top of most injector pumps. One direction is run and the other idle. That's probably what the tech had his finger on.

 

[sesesene]

Does anyone know where I can get the service manual for an Onan 8MDKDB 1C generator?

It has never worked since I bought the boat. It will start, but not keep running.
I had a generator guy come out to look at it. He did something (wouldn't show or tell me what) to hold the throttle that got it to start and run, but as soon as he took his hand off, it died. He said something was telling the generator to stop...

The remote panel was disconnected by the service company that the previous owner tried. The new guy said that some generators (maybe this one, maybe not?) were set up that the generator would die without the remote panel, and needed a jumper to run without the remote panel.

Unfortunately, while the generator guy seems to know what he's doing, I haven't been able to get him to come back and work on it.

Maybe if I could get the service manual, I could at least get the remote panel hooked back up, and possibly debug the rest??

Thanks!
John

Still need a copy