Onan 9MDKAV water flow blocked

Blueone

Well-Known Member
SILVER Sponsor
Jan 24, 2007
13,688
Lake Erie, Ohio
Boat Info
2004 420 Sundancer
Engines
Cummins 6CTA 450's
image.jpeg


I lost what I suspected was the impeller as you can see. I replaced it and removed the hose to the intake side of heat exchanger and got a few rubber pieces out but no where near the amount that is missing. I started the generator with the hose removed and had good flow. Put the hose back on and get no flow out the side of the boat and the generator shuts down (which is good to know). I tried to run a water hose in the exhaust to back flush the blockage but it didn't work at all.
Now I can't get down thru the narrow hatch to get to the heat exchanger without removing the exhaust tube from the port engine. Has anyone had a similar problem and fixed it without ripping everything apart ?
 
I recently lost an impeller too, replace new impeller and took the hose off the heat exchanger and water pump to strainer and back flushed a few pieces out also picked as many pieces that I could out of the bottom of the heat exchanger. Generator ran good for a day and then would not start again. This time I called the machanic and this is what he did.
Removed discharge hose from impeller pump

Started generator (pumping lots of water)

Removed end cap of heat exchanger(was completely plugged with impeller pieces)

Removed impeller pieces from heat exchanger

Removed discharge hose of heat exchanger and back flushed with water

Removed discharge water vented loop and cleaned all the impeller pieces from vent

Reinstalled all the hoses and end caps

Started generator(it was pumping water now)
 
I recently lost an impeller too, replace new impeller and took the hose off the heat exchanger and water pump to strainer and back flushed a few pieces out also picked as many pieces that I could out of the bottom of the heat exchanger. Generator ran good for a day and then would not start again. This time I called the machanic and this is what he did.
Removed discharge hose from impeller pump

Started generator (pumping lots of water)

Removed end cap of heat exchanger(was completely plugged with impeller pieces)

Removed impeller pieces from heat exchanger

Removed discharge hose of heat exchanger and back flushed with water

Removed discharge water vented loop and cleaned all the impeller pieces from vent

Reinstalled all the hoses and end caps

Started generator(it was pumping water now)
That's what I thought...how the heck did he get in there?... One dock mate said that's what grandkids are for....unfortunately I can't wait that long :(
 
With the floor lifted on your 420 you can then remove the skinny piece that would be in front of you as you step through the transom door. After that floor piece is out you can remove 4 bolts and the aluminum support will come out. It is a lot easier to access the generator that way. It will still be a tight spot however.
 

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