Onan Woes

[Liquid Asset]

First off, I have to say that I hate my onan. But on that note, now that we have the engine rebuild done we went to crank up the genny and it is giving us the same misterious problem we had last summer and never figured out.

Basically, when you click the start button, you get nothing but a clicking relay. Though it seems like you do not have power, we have plenty and if you jump the starter, it runs like it should. We spent all day working on it and can not seem to find a problem. It is a 15MDAK. WE replaced all the relays except for the starting relay that is special to the onan. We replaced or tested all the rectifires. No luck. We can not seem to find the problem. Does anyone have any suggestions? Both the mechanic (not an onan specialists) or I have no Idea. Help would be appreciated.

 

[MikeP]

Could be a bad cable/connector to the start relay, bad wiring from the start switch to the relay or a defective relay.

As you said, if you can jump (bypass) the solenoid and the starter will spin, you have sufficient battery power. Can't think what else might cause the problem

 

[chris piazza]

Take it from someone who hates my onan, you could have a bad solenoid in the starter or more than likely a "Flat" spot on the start windings in the starter. I would pull the starter and have it re-wound at your local shop, last one I had done was less than 100.00.

Chris

 

[krush]

hammer to the starter case sometimes solves the problem.

 

[clark leighs]

It does start when you bypass the start relay and jump the starter? So the starter motor or starter winding itself appears to be ok.
So maybe the start relay is the problem. Maybe there is a contacts repair kit from Onan.
Check that you have voltage at the start relay on the main power contacts. Then move the meter lead to the other side of the start relay and try to start. Do you have voltage there also? If not then the contacts are likely burned open.
You said you heard clicking when pressing the start button. Can you watch & check if the Start relay itself is operating. If it does then the main power contacts are the most likely cause of your trouble.
If need be, check also the relay coil leads and that there is a ground connection on the negative side.
Put your meter on the + side of the coil and try start. If you have power, I'm assuming 12V controls, then you should see 12 v or nearly so. If not then your cct. ahead may be the problem. These relays coils work against a fairly strong spring to ensure contact opening so need near full voltage. If all's well here then move your meter lead to the - side of the coil and try again. You should have almost no voltage reading. If you have voltage then the - lead of the coil is open . The coil itself can be checked for continuity with the ohms function.

 

[Liquid Asset]

The generator never does start. I can jump the starter silanoid so that it will run the starter, but that does not cause the engine to start because all of the other electrical items are not being engaged.

There is plenty of power for this to happen, but it does not seem that something is working correctly in the DC starting system. I just am not an Onan tech, so I have no Idea. The best I can explain it is that whatever is soposed to actuate all of the relays is not doing it and I can't claim to be the best person at reading schematics. It does look as if the starting relay (8 wires) may be bad, but I dont know about the safety switches. If one of the safety cut off switces is bad and will that cause the generator to do nothing when trying to start it?

 

[TomT13]

When you say starter relay do you mean the fuel solenoid? When my batteries were low and I tried to start my generator the fuel shut off solenoid made a clicking sound like you describe. When you activate the starter button that makes the fuel pump come on and pulls the fuel shut off solenoid back. If this doesn't happen the engine will not start. Just something to look at.

 

[Starman]

Just for info in case any one is interested........

I have found boxes of cool Onan supplies, like brand new carbs and many other items.

Just send me your wish list , with enough info ( part numbers etc.......if you have them ) and I will see what I can get you: The price will be right !

 

[Liquid Asset]

We got it to run, but we screwed up in the process and reversed a rectifier and it melted because it was in backwards. The ONAN part number is 357-0030. Does anyone know how to build a rectifier? It has flat blade connectors. One in and one out. From what I understand, it is only a diode, if so, can I just go to Radio Shack and buy a diode and install it temporaraly untill I can get the correct part? Help would be appreciated because I want to use the boat tomorrow.

 

[Trojan]

Its must be big enough. Where was the diode used. It's hard to believe you fried the rectifier.
You can go bigger but not smaller.
BILL

 

[JLR]

Although this is many years ago, do you recall what caused the problem? Sounds like I may be in the same boat.

 

[REBrueckner]

What relay is clicking??

"...you could have a bad solenoid in the starter.." my guess....

 

[Canuck Dennis]

Check the main ground wire on the engine..corroded I bet.