[C320-list] Overheating

[Jack McDonough]

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