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What Have You Done to Your Onan Generator Today?

Max Thompson

Sponsor
Last Subscription Date
09/03/2019
Leon, I will defer to you on this one, you have much more experience with electricity and JBs than I do.

Without looking at a diagram or a JB control box, I can not say. But, I thought the Hand Crank position fed 12-V straight to the coil, bypassing the start disconnect / ignition relay, which is why you can not shut it down with the Stop switch.
 

Leon N.

Registered
Leon, I will defer to you on this one, you have much more experience with electricity and JBs than I do.

Without looking at a diagram or a JB control box, I can not say. But, I thought the Hand Crank position fed 12-V straight to the coil, bypassing the start disconnect / ignition relay, which is why you can not shut it down with the Stop switch.
Hi Max

The Hand Crank switch only bypasses the start disconnect/ignition and start ignition relays. The 12 vdc before going to the ignition coil first passes through the low oil pressure emergency relay, normally closed contact. The later is ready (primed) once the oil pressure comes up and the centrifugal switch closes.

The high temp cut out switch is in series with the ignition coil primary and works independently of the hand crank switch.

If the plant experiences a over heat shut down while in the hand crank position, the low oil pressure switch will close, activating the low oil shut down relay, you know that red button will pop out and the gas valve, electric pump accessories will also be deactivated.

See for example, page 81 in 967-500.

Leon
 

JohnnyC

Subscriber
Last Subscription Date
07/13/2019
Very high winds this evening in north Jersey. Waiting for the power to go out, but not a single blink (yet) and it is 10:40 pm.

JohnnyC
New Jersey
 

slip knot

Subscriber
Last Subscription Date
12/27/2019
The unit takes about 50 gallons of coolant and it was still full at the radiator. very slight leak where the hose was melted at the connection. The wiring is burned back into the conduit and is completely melted at the handybox on top. The genset alarm panel was showing coolant over temp. The box on the side is the relay to cut the heater off. the only time it turns off is when the unit is running. that all seemed to be working OK. The unit ran an exercise cycle Tuesday so I don't think it was an issue at that point. we did change out the breaker on the heater system. it should have tripped long before we got to this point. The heater elements are shorted to ground, not sure if that's a cause or a result though.
we put a hose to bypass this heater and ran the right side heater for 1/2 the day Friday and it brought it up to temp but was a bit slow. These are pretty good sized heaters, 240V, 4000W with a circulating pump on the bottom. I'm leaning towards the pump cratering on that unit.
 

Eric.S

Registered
Check if there is a non return valve in the heater, bypassing the heater might short part of the engines waterpump flow.
block of the heater connections instead of connecting them.

Eric
 

slip knot

Subscriber
Last Subscription Date
12/27/2019
We'll be getting a pair of new block heaters ordered ASAP but I didn't want to leave it off line over the weekend. it appears that each heater feeds a side of the engine. draws from the rear and puts it back in the front kinda thing. We just hooked a hose from the inlet to the outlet connections, didn't think to look for check valves. Hopefully it isn't needed this weekend.
 

Zephyr7

Registered
It’s not uncommon to have two block heaters on bigger engines. Usually one heater on each bank of cylinders.

I agree with the other posters — looks like you lost coolant flow through the burned up heater. You can get separate overtemp cutout switches to help protect against that. My smaller genset at home just relies on natural convection circulation and when my block heater magically changed from dead to stuck on last winter, it kept running for a week before I found it — keeping the engine up around operating temperature but not burning up. Normally it would keep the engine a little cooler than real operating temperature.

Good thing you didn’t have that hose fail and leak out all your coolant thus killing the other block heater too.

Bill
 

Farmer Jon

Registered
Fired it up to exercise it this month and its surging real bad. Last time i used it about a month ago it ran so smooth. I'm getting fed up with it. Seems like one problem after another with this thing. Little help with the shop I bought it from. I found a new guy to take it to. One last chance before it goes in the junk pile. Buy a used one I said. Save money I said. With all I spent on this thing I could have bought a brand new one.
 

zuhnc

Subscriber
Last Subscription Date
12/08/2019
I talk to mine, hibernating in the garage, on my way to my shop to work on the load bank. They don't seem to mind not working; they are dry and reasonably comfortable. I did fire up the 8N tractor today to move some round bales for the horses. Like all the old Onans, didn't complain at all, even though it was 25*F. zuhnc
 

Power

Registered
Fired it up to exercise it this month and its surging real bad. Last time i used it about a month ago it ran so smooth. I'm getting fed up with it. Seems like one problem after another with this thing. Little help with the shop I bought it from. I found a new guy to take it to. One last chance before it goes in the junk pile. Buy a used one I said. Save money I said. With all I spent on this thing I could have bought a brand new one.
As others have said, you should only buy used if you are handy and can maintain your equipment. If you have to pay someone to do it, quickly gets expensive.
Never seen yours- seems you have a fuel problem. Are you using fuel with ethanol? Did you drain fuel after last run?
Onans are so reliable, I never exercise mine. I prepare for storage and let sit until next outage, confident they will start. Occasionally roll engine over a few turns.
 

Ray Lynch

Subscriber
Last Subscription Date
08/12/2019
Fired it up to exercise it this month and its surging real bad. Last time i used it about a month ago it ran so smooth. I'm getting fed up with it. Seems like one problem after another with this thing. Little help with the shop I bought it from. I found a new guy to take it to. One last chance before it goes in the junk pile. Buy a used one I said. Save money I said. With all I spent on this thing I could have bought a brand new one.

Is this the 4.0 BFA?
Ray
 

Farmer Jon

Registered
Yep 4.0BFA. I do not drain the carb after each use. But I do run it every month. I do not use any ethanol at all. I get my gas from the farm. We have several antique tractors that don't like ethanol. So I make a deal with the boss and get my gas from him.

I have an appointment to have it looked at Tuesday morning but over the phone the mechanic said probably looking at a carb rebuild. The idle jets are probably plugged.

Sorry about the rant.
 

Ray Lynch

Subscriber
Last Subscription Date
08/12/2019
Yep 4.0BFA. I do not drain the carb after each use. But I do run it every month. I do not use any ethanol at all. I get my gas from the farm. We have several antique tractors that don't like ethanol. So I make a deal with the boss and get my gas from him.

I have an appointment to have it looked at Tuesday morning but over the phone the mechanic said probably looking at a carb rebuild. The idle jets are probably plugged.

Sorry about the rant.
Does it surge both with or without a load?
Ray
 

HBSkirmit

Registered
My old Onan 30EK is putting out voltage like a new one, after installing the SX460 AVR. I've decided to install a muffler, since I have been running it straight out of the exhaust pipe (with a rain cap) for over 20 years. I live in a rural area and the closest neighbor is my grandson, who owns a paint & body shop next door. I didn't think the noise bothered anyone, until my 2 year old, great granddaughter came to visit. I didn't even know she was here and I was outside starting the engine. When the engine started, my wife run out and told me to shut it down because great granddaughter started screaming and crying louder than the engine. I've got the muffler on now, but the granddaughter will be the best judge of the quieter engine !
 
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