[C320-list] Overheating

[Jack McDonough]

Bruce:

Thanks. I'll take another look at the impeller with that in mind. Also, now 
that you mention it, I wonder why the hose to the impeller is tied up the 
way it is, making the pump pull the water uphill from the strainer? Must be 
a reason. (But, then, I don't see any reason for putting the fresh water 
valves under the quarterberth, either. My pet peeve.)

jack


----- Original Message ----- 
From: "Bruce" <bruceheyman at cox.net>
To: <C320-List at Catalina320.com>
Sent: Monday, August 15, 2011 9:09 AM
Subject: Re: [C320-list] Overheating


> While the impeller maybe fine maybe the back or inner face of the pump is 
> worn and hence not always able to prime the pump leading to the low or no 
> flow. Also there is an insert in the pump (can't recall what it is called) 
> that is usually replacable. If this is worn then both the amount of water 
> and the amount of vacume it can pull to prime the pump is reduced. I 
> assume the pump is not leaking.
> I had a similar problem and found that when I cut the ty wraps that held 
> the intake (to the pump) hose up and then lowered the hose as low as I 
> could the pump move a lot more water. I ended up taking the cover off and 
> using a sanding disk removed the scratches.  Kept moving to finer and 
> finer sand paper and then the last step was to polish it.  After that I 
> was able to put the hose back to its original position and it has woorked 
> fine ever since.
> Bruce
> Somerset 741 Dana Point
>
> Bruce Heyman
> 949-289-8400
>
> -----Original message-----
> From: Jack McDonough <mcdonough5 at verizon.net>
> To: C320-List at Catalina320.com
> Sent: Mon, Aug 15, 2011 12:47:20 GMT+00:00
> Subject: [C320-list] Overheating
>
> A puzzling, intermittent overheating problem developed a couple of weeks 
> ago with the 3GM30F Yanmar in my 2003 C-320.
>
> While traveling at low speed from an anchorage to a newly available 
> mooring one morning (maybe 10 - 15 minutes running time), the engine 
> overheat alarm sounded. I managed to pick up the mooring, after which I 
> pulled the raw water intake hose at the seacock and determined that water 
> was, in fact, coming into the system. I then checked to see that the 
> strainer was clear and, finally, took apart the impeller housing and 
> inspected the impeller -- which was newly installed in May and which 
> looked fine. I started the engine again and still got only steam out of 
> the exhaust. A couple of tries later, however, the system once again 
> pumped out water like a champ.
>
> I made a three-hour passage to another harbor under power the next day and 
> everything was fine -- but the same problem occurred the following day. 
> Again it blew steam -- but the following morning I got a healthy flow of 
> water and headed home.
>
> Since then, I have again pulled the hose off the intake seacock but, this 
> time, I took my digital wire coat hanger and fed it down through the 
> intake passage to make sure there was nothing flopping around in there. I 
> disconnected the other end of the hose -- at the strainer -- and detemined 
> that there was nothing in the hose. Then I removed the hose between the 
> strainer and the impeller and confirmed that it, too, was clear.
>
> I have a sense that I'm more likely to be able to pump water if I briefly 
> goose the RPMs up to 2000 or a little more. But I've consulted my diesel 
> guy and he says that shouldn't make any difference. It should pump water 
> regardless.
>
> That's my story. Any ideas?
>
> Jack
> #947
>