Onan MDJA stop solenoid

[Dwk]

Our Onan MDJA 3.5 generator starts easily,produces plenty juice but the stop solenoid does not stop the generator. Looking for advice to repair,replace the stop solenoid or any other method to stop the genset BESIDES shutting off the fuel supply. I have looked extensively for a replacement……no dice.

 

[Gdavid]

Our Onan MDJA 3.5 generator starts easily,produces plenty juice but the stop solenoid does not stop the generator. Looking for advice to repair,replace the stop solenoid or any other method to stop the genset BESIDES shutting off the fuel supply. I have looked extensively for a replacement……no dice.

I dealt with this over the summer, it turned out to be the ground strap on the generator to the case breaking through causing other circuits to short out repeatedly. I ended up with a spare stop solenoid in the process.

 

[Portage_Bay]

If Gdavid's suggestion doesn't work take a pic of your solenoid and PM me. I may have one that will fit.

I'm trying to keep a MDJE up and running, it's been a challenge finding parts. Cummins bought Onan and supports some of the Onans, I've had some success getting parts from them. They orphaned some of Onan's line. It may seem parts for those machines are made from unobtainium. It takes a lot of time but they can be found. Some are getting pricey.

In order of best sources for my old Onan

• Cummins still has some old stock. OEM stuff, good quality if they have it
• onanparts.com some OEM, some after market
• Ebay can be a source
• Membership at Smokstak.com is worthwhile. A very knowledgeable group over there
• Hatton Marine in Seattle has a parts dept that can sometimes help
• Jacks Small Engines, a long shot but maybe....
• Sometimes even CraigsList will turn up useful parts

 

[Gdavid]

The Onan part number is 307-1098 and the solenoid is made by prestolite, the prestolite number is on it, which is not in front of me. I need to retest it and confirm that I didn't burn up this spare one in the process of getting mine up and running, the one I bought was brand new-old stock but I did paint it. Assuming I didn't damage it, you are welcome to it. I'll pm my phone number, I'm in Maryland as well, south of Annapolis, right by Herrington Harbor South.

 

[jgwinks]

The solenoid itself might not be bad, sometimes they get stuck and a little lube will fix it. The stops on the old Detroits in the tour boat I ran did that about once a year. We'd shut it off manually, squirt in a little lube and it would be good for another year. Those engines are about 60 years old

 

[ksanders]

So...

If memory serves correctly the DJ series of engines used a energize to run actuator against the fuel rack overcoming the governor spring tension.

If the engine continues to run the problem would be in the spring in the solenoid which should be easy to replace, or it might just be out of adjustment.

I do not remember if the solenoid was push or pull when energized but I'm pretty sure it was energize to run.

 

[Gdavid]

So...

If memory serves correctly the DJ series of engines used a energize to run actuator against the fuel rack overcoming the governor spring tension.

If the engine continues to run the problem would be in the spring in the solenoid which should be easy to replace, or it might just be out of adjustment.

I do not remember if the solenoid was push or pull when energized but I'm pretty sure it was energize to run.

The little single cylinder uses a solenoid to operate a compression release, it holds the exhaust valve open. It actually has two circuits within it so it takes less amperage to hold the spring back than to actuate it in the first place. It works by starting to crank, and get over top dead center before engaging the solenoid and allowing full compression. It uses a oil pressure sensor to control this. If you do away with this solenoid and shut it down manually, it will struggle to start, depending on the position of the piston when it shuts off.

 

[ksanders]

The little single cylinder uses a solenoid to operate a compression release, it holds the exhaust valve open. It actually has two circuits within it so it takes less amperage to hold the spring back than to actuate it in the first place. It works by starting to crank, and get over top dead center before engaging the solenoid and allowing full compression. It uses a oil pressure sensor to control this. If you do away with this solenoid and shut it down manually, it will struggle to start, depending on the position of the piston when it shuts off.

Very cool, I have never seen the one cylinder. Completely different beast!

Does it still retain the fly ball governor of the larger ones???