[C320-list] Overheating

[Jack McDonough]

Herb:

I was referring to the RPM setting when I start the engine (around 1100). 
While cruising I'm usually around 2500 to 2600. But your advice is well 
taken. I'll kick it up a couple of hundred and see how it sounds and feels 
at 2800 or so..

jack

----- Original Message ----- 
From: <hcreech at comcast.net>
To: <C320-List at Catalina320.com>
Sent: Monday, August 15, 2011 9:13 AM
Subject: Re: [C320-list] Overheating


> Jack,
> Unless I am reading this wrong you are running your engine at too low a 
> rate of speed. This should not have any bearing on the water pump 
> situation but still way too low. If you continue to run at that low speed 
> you will only create a carbon build-up which is not good. I run mine 
> continuously while crusing a 2800 RPM and only lower speeds while docking. 
> When I took the initial diesel class they stressed that low speeds are 
> very detrimental to diesels. They went on to say you should cruise at 
> 2800-2900 RPM and can run at 3100 RPM for up to an hour without causing 
> any problems. The main point was to "Not Baby" the diesel. Could be 
> another problem, but regardless, if I am reading this right, you need to 
> crank it up.
>
> Herb Creech
> Cloud Chaser 606
>
>
>
> ----- Original Message -----
> From: "Jack McDonough" <mcdonough5 at verizon.net>
> To: C320-List at Catalina320.com
> Sent: Monday, August 15, 2011 8:47:20 AM
> 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