Onan genset trouble code "seven blinks"

John Clark

Hi All,

  I case anyone has not seen this before.  Started the Onan 7KW generator after a passage and it turned off shortly after starting.  It gave the seven blinking light trouble code.  My manual indicates this is the “no sea water flow” shutdown.   Don't force the generator to run if you get this code and there is no sea water coming out of the exhaust, like the situation we were in tonight.


Checked the obvious sea strainer all good, then broke out tools  to open up the sea water pump and discovered only two vanes left on the impeller.  Installed the onboard ready spare (you should have at least one spare all the time)  but on restart continued to get the no flow shutdown.  Pump was full of water and all vanes aligned correctly.  Checked down stream and found the heat exchanger inlet plugged with …..you guessed it, impeller vanes.   After clearing all the debris and repriming the sea water system the genset is back on line. 

Note, all these steps were rather simple, just a bit tedious.  The pump was easy to open, impeller pulled right out.  New one was a bit of a four letter pushing match to get into the housing but eventually my thumbs won.  The heat exchanger had one bolt to remove the end cap and then used tweezers to pull out the bits of impeller plugging the heat exchanger.    Will post pictures on the FB page. 


Take home message, onboard spares, and “yes you can do it yourself with a little patience and common sense.  This repair cost us one impeller, ($30USD)  and 1.5hr labor.  How much would an Onan technician charge us for this repair?  


                   Regards,  John


John Clark

SV Annie  SM 37

Just moored at St.  Augustine for Christmas

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