onan

I have a generator onan and sons model # w3m, 2 cylinder manual crank start wico mag, can any one tell me how old it is? Any Ideas how to start by batteries? Thanks Lee

I don't have a manual for this model and have found there are many more models of ONAN gen sets than I ever suspected. ....anyway on a lot of the electric start gen sets there was a starter solenoid/relay just like most older cars have. It is an electric switch to connect the battery to the starter windings of the gen set. The ones I've seen on Onans look identical those in cars a small can 2" or so high, with 2 large terminals one on each side and then a single much smaller terminal on the side that the mounting bracket isn't on. If you have a control box on top of the generator it likely is mounted on the inside of the upper covers. It would have 2 large cables 5/16" to 3/8" dia connected one to each large terminal on the solenoid. If you follow the wires back to their source one would go down inside the generator itself and the other should go to a terminal on the side of the control box, hopefully it has a + symbol near the connection on the outside of the box or else it may have a white circle around the terminal. ....anyway this term should connect to the + side of the batt. the - side of the batt needs to connect to the frame of the genset or if there are 2 terminals on the side of the control box the other one may be labeled - and the - term of the batt connects there. A lot of the older Onans had a cap on the bottom of the solenoid that would unscrew and under it was a button that when pressed would close the contacts and normally cause the engine to be spun by the starter. So you can bypass some of the internal wiring by actuating it manually to start with. There's several considerations that may affect you. if this gen set is a 32v battery charging unit then it might need to have 32v of batt. avail to make it go. I haven't seen + ground Onans but have seen several other brands with positive ground systems. If you hook the battery up backwards the starter usually won't care and may work OK, the big but here is that the battery charging ckt if it was funtioning before hand may get damaged when it trys to charge the battery backwards.....not sure what would give but it might smoke something if batt connection is backwards. Even if it is a 32v gen set it may have 12v starting windings and may just need a single 12v batt, in any case using a 12v batt won't hurt anything if you try it, it just won't spin much. Your unit may not have elect start, if it does some had external starter motors, but the majority had starter windings built into the generator, with a single large wire coming out of the generator. Basically you put 12v to that wire the gen set should spin. If you have coils and points you need to find out where the power was physically supplied to the ignition system and then make sure that there is power there. On my Onan the points are connected electrically between the coils and ground, so the wire went from the points (one side of points is grounded) to one coil then the other terminal on that first coil was connected to the other (second coil) and the +12v from the battery was connected to the second terminal on the second coil. If there's 2 coils then they are likely connected in series so the terminal that connects to the points on one coil should be marked the same on that coil as the terminal on the second coil that is connected to the first coil. There is a simple check to see if the coil polarities are correct but it some times is a shocking experience, it requires the sparkplug wire to be held about a 1/4" from the top of the spark plug then the lead of a sharpened wood pencil is held in the center area between spark plug and wire then some one spins the engine and you observe which side of the pencil the arc occurs on, do this again with the other sparkplug and make sure the arc occurs on the same side for both sparkplugs. The arc should be towards the plug I believe but am not certain. If the battery is connected to the first coil to the + term on the coil then use what happens on its test as an example for the other. If the coils are not connected with correct polarity then the engine will be hard to start and won't carry a load like it should because the spark plug ignition voltages will be low. Again I got windy sorry about that. I have verfied that my e-mail works now so if you wish we can continue that way if u wish.

Hook up battery cables through a solenoid to the POS.and NEG. brushes on the comutator (the ring of segmented bars made to transmit D.C. current.)

Do not hook batterys to brushes from slip rings!! (solid round rings to transmit A.C. current)

12 volt should work, if not try 24 volt. If comutator has four brushes, hook battery cables to adjacent brushes, not to brushes on opposite sides of comutator.

Thanks guy's but this has no solenoid, that I can see? it has wico mag, and control panel is on the back side of engine, panel has a stop button tog switch for panel light and what appears to be a breaker type switch says on/off. Is it possible this is a manual engine? crank is on front below radiator. Thanks Lee

I have a W2C, which I gather is pretty much the same as the W3. The W2 was offered in AC, DC and battery charging versions, it was also manual or battery start. If your plant has a control panel, my guess is that it is battery start.