[C320-list] Overheating

[Dennis Harris]

Just a thought...could it be that a broken water pump vane or other debris 
is in the exit end of the heat exchanger?  It could be loose so it moves 
around but big enough to stop water flow out the exit if it stops across the 
outlet opening.  On time, water turbulence moves it away from outlet opening 
and you get normal pumping/water flow.  Next time, turbulence moves it so 
that it blocks the outlet, in which case, you get no flow and steam.

Dennis Harris C320 694.

----- Original Message ----- 
From: "Jack McDonough" <mcdonough5 at verizon.net>
To: <C320-List at Catalina320.com>
Sent: Monday, August 15, 2011 11:50 AM
Subject: Re: [C320-list] Overheating


> Dave:
>
> Yes, you may be right. The trouble may well be downstream. I was hoping I 
> could avoid pulling more stuff apart but I guess I'll have to bite the 
> bullet. Thanks for the suggestions.
>
> jack
>
>
>
> ----- Original Message ----- 
> From: "Utility Email" <kswanson123 at comcast.net>
> To: <C320-List at Catalina320.com>
> Sent: Monday, August 15, 2011 11:05 AM
> Subject: Re: [C320-list] Overheating
>
>
>> Could there be a partial blockage in the mixing elbow or a partial 
>> blockage upstream of the strainer?  It sounds like you have thoroughly 
>> checked upstream of the pump, perhaps checking downstream might find the 
>> culprit?  If it came on suddenly, that would point to some type of marine 
>> life blockage was ingested, but of the strainer is clear, then it would 
>> have to be upstream from that. I am guessing:
>>
>> 1. That the mixing elbow may have carbon/corrosion build up.
>> 2.  Water pump is not functioning adequately at low speeds.  I'm guessing 
>> that the water pump is not providing enough head to force water through 
>> the system. Seems like there could e a easy way to test this buy 
>> connecting a long clear hose between the pump outlet and the engine.
>>
>> Dave Swanson
>> S/V Emily Ann
>> 2007 C320 MK II, No. 1107
>> Mukilteo, WA
>>
>> On Aug 15, 2011, at 6:13 AM, hcreech at comcast.net wrote:
>>
>>> 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
>
>