[Amel Yacht Owners] Onan Generator Troubles
Stephen MORRISON <steve_morrison@...>
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Duane. I had these very same codes and my generator often shut down within the first two minutes of running. I had Cummings come out and look it over and it turned out to be the exhaust sensor. A little fumbling with the wires and it has run smooth ever since. I did order a spare sensor to have on hand but the Cummings service guy said I could also just connect the wires directly and bypass the sensor as a fix if needed as in his opinion, so long as water was running through, which has its own sensor, the exhaust cannot get hot enough to be a problem.
All the best,
On Apr 23, 2017, at 11:01 AM, sailor63109@... [amelyachtowners] <amelyachtowners@...> wrote:
Wow! Steve! You were exactly right. One of the wires on the temperature sensor was disconnected...the screw had fallen out. I'm amazed I didn't notice that when I was looking at the exhaust elbow and trying to determine whether it was hot.
As I write this the genny is humming along, happy as a clam, pouring amps into the batteries and making water.
Are you going to be in Brunswick this summer? We're headed there in early July for hurricane season. Be nice to meet and buy you a beer or two!
Thank you for the help!
Outside No Name Harbor, Key Biscayne
Bill & Judy Rouse <yahoogroups@...>
Use your ohm meter to check for continuity between the terminals on the temperature sensor on the exhaust elbow. That temp/sensor/switch is normally CLOSED. As the exhaust elbow temperature rises above the switch tolerance, the switch OPENS.
Remember there are a number of sensors in the shutdown system, and these switches will fail. I replaced the exhaust manifold temperature switch and the waterflow switch because of failures. I also had one situation with a loose connection on a switch.
Did you use your laser temperature gun to measure temperature? The normal temperature of the exhaust elbow is about 50C and the normal temperature of the coolant is about 80C. Were these in range? How many hours since the last impeller change?
The impeller blades can look OK, but the impeller be defective:
I would bet big odds that you have an impeller problem because one blade was in the opposite direction...I believe that with a good impeller and pump, this should never happen. I believe that you may have one of the above situations going on with the impeller and you should not only replace the impeller, but also, with a high degree of certainty, eliminate the potential problems that I listed above.
HINT: It is always easier to remove the Onan saltwater pump (two bolts) to replace the impeller. Have your wet-vac available and a large shop towel to eliminate any possibility of saltwater getting on anything.
Good luck, and I hope this helps.
CW Bill Rouse
Admiral, Texas Navy
720 Winnie St
Galveston Island, TX 77550