[C320-list] raw water...still!

[Scott Thompson]

Jim:  Your clear hose was bypassing the vented loop in the cockpit 
locker, not the hot water heater.  (The hot water heater circuit uses 
antifreeze and is not in the raw water circuit.)

You don't say whether you checked the output of the pump directly.  It's 
still possible you have some hidden restriction in the heat exchanger.

The scoring could be a problem.  If that's the case you might consider 
purchasing a "SpeedSeal" replacement cover for the impeller.  I 
purchased one of these mostly because I was tired of dealing with all of 
those little screws.  These things are primarily designed to make it 
easy to remove the impeller cover for inspection or replacement, 
something that doesn't work very well on the Yanmar engine because of 
the placement of the cover.  However it still makes it easier and 
quicker to remove and reattach the plate.  I have one and they are very 
well made, with high quality machining of the cover plate.  They are a 
bit pricey however.

I notice that there is a newer version that actually has a separate 
bearing plate for the impeller that prevents the rubber from rubbing 
against the cover plate entirely.

See http://www.speedseal.com.

Scott

james_delong wrote:
> Y'all,
> 
> My raw water saga continues...and I'm exacerbated enough to replace the pump as a final step!
> 
> For those who still have interest, this is what I've done.
> 
> Sea cock open and clear - strainer clean -  all hoses open.  Disconnected the intake hose to the pump and opened the sea cock - good flow to the pump.
> 
> Opened and cleaned the heat exchanger. All looks good - hoses clear.
> 
> Removed and cleaned the mixing elbow - all clean.
> 
> Attached a clear by-pass hose from the heat exchanger output to the mixing elbow bypassing the water heater (I think).  Started the engine.  The clear hose exiting the heat exchanger had VERY little flow.  Stopped the engine and disconnected the heat exchanger input.  Very little water came out.
> 
> Conclusion:  good input into the pump - very little out.....must be the pump even though I fine no evidence it is bad.  No leaks, rotation seems strong.
> 
> Focusing on the pump:  impeller and gasket were changed.  The endcap has a lot of rotational scoring on the inside.
> 
> Questions:  Would this scoring create enough cavitation to restrict the flow?  If so should I replace the endcap (even if one can) or the entire pump?  What else in the pump could cause limited water flow?
> 
> Thanks!
> 
> Jim  #453

-- 
Scott Thompson
Surprise, #653