Onan Genset Controlled Shutdown

[fishheadbarandgrill]

My genset did a controlled shutdown a couple of days ago after 15 minutes of run time. Based on the flashing light sequence, the code was 58, high exhaust temp. The operators manual recommends several steps to correct, most are related to raw water flow. I called Cummins tech support and they emailed me the service manual which provided more detailed troubleshooting steps, including testing for bad sensors. I suspected an obstructed thru hull because I was getting water flow out the exhaust and I didn’t get a raw water alarm. I dove on the boat and inspected the thru hull and cleaned out a few small barnacles. I Ran the genset for 30 minutes without an alarm. My conclusion is that the thru hull is small and doesn’t take much to obstruct the water flow.

 

[Martin610]

Did you check the genset impeller?

 

[fishheadbarandgrill]

Did you check the genset impeller?

Did not. If the impeller was bad, I’d have had a “No Raw Water Flow” alarm. I could visibly see water waiting the exhaust port. Tech support confirmed that assessment. I think there was just enough of an obstruction to overtemp the exhaust sensor. I used a heat gun aimed at the block (160F) and heat exchanger (140F) after the thru hull was cleaned.