onan gen

I finally got my onan generator home for a closer look. The plate on the generator reads: model m 3 w ser 82.39585, 115 volt 5000 watts.

The engine is two cyl. w/radiator but no water pump. Anybody have a clue?

Onan uses what is called a thermal siphon (hot water rises) process to circulate water between the engine and radiator. There are many water pump less Onans. The radiators on their gen sets are slightly oversized compared to a similar unit w/water pump, there is even a thermostat of such but it isn't a physical device. The design of the block head and radiator all work together to keep the block and head at a good operation temp, i.e. the more heat in the engine the faster the column of water in the radiator outlet of the engine rises, taking more heat to the radiator. I don't think you want to let the fan belt get very loose because it very definitly depends on the large amount of forced air thro the radiator to keep it relatively cool so the thermal siphon will move the heat out of the engine. For many Onans there are 2 manuals one is a parts manual with exploded views of subassemblies and then there is an operators or instruction manual. I have many manuals but none for your rig. I think there is a reference to a person at Onan who can get copies for you later on this bulletin bd. If you don't find it get back to me, perhaps I was thinking of something I saw on another bd. I can see if I can find it for you. I haven't recieved any mail at my E-mail addr listed here. I just got the service and apparently wrote something down wrong. I'm hoping to get it fixed tomorrow.

Thanks Jack, Your info is very helpful. I will keep in touch. I wouls like to get more info and a source for parts. thanks again.