Re: [Amel Yacht Owners] Onan genset trouble code "seven blinks"

Thomas Peacock

We have had similar, recurrent problems on our SM #240. For some reason, the impellers we buy for the Onan have a tendency to lose blades, which then get trapped. By comparison, we have not noted that with the Volvo drive engine. 

One thing I have noticed: even when the engines (either Onan or Volvo) are not putting out sufficient water, there is a “throaty” exhaust sound. 

Even better, which I don’t think I can pass on, is what happened when I had an expert on board to look at a water flow issue. He put his hand on the side of the Onan, just downstream of the impeller, felt the surface for a couple of seconds, and diagnosed the problem immediately.

But you’re right, the fix is well within anyone’s skills who follows this Amel site.

Tom Peacock
SM #240 Aletes
Falmouth Harbour, Antigua

On Dec 16, 2017, at 9:21 PM, john.biohead@... [amelyachtowners] <amelyachtowners@...> wrote:

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 … 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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