[C38] engine temp

[Ann Boochever]

Even with 52 degree water in Alaska, our 2" heat exchanger has been just
passable at 2400 rpms. Is there an off-the-shelf replacement that is larger
and would fit in the same location, or do they have to be built to order?
Thanks
Scott and Ann
Tacita II
Juneau, AK

On 9/1/09 5:48 PM, "Les" <hlhowell at pacbell.net> wrote:

> Thanks, Tom,
> I figured you would be the one with the answer.  I am an engineer
> wannabe, so I study things pretty thoroughly, but I find I sometimes
> miss a detail, such as the one you point out here.  Too hot is not good
> for any engine.
> 
> Regards,
> Les H
> On Tue, 2009-09-01 at 21:11 -0400, Tom T. wrote:
>> Hi Les,
>> 
>> You claim you don't want to appear stupid and then you go on to show you
>> are fairly astute about diesel engines.
>> 
>> As you pointed out, the thermostat should regulate the engine temperature
>> for optimum performance.  The problem we have is that the original heat
>> exchangers on many of our engines were just too small and if the water
>> returning from the heat exchanger is still hotter than the operating
>> temperature of the engine, the engine is gonna overheat, clear and simple.
>> 
>> You cannot have a heat exchanger too large but you can have one too small.
>> If you had a heat exchanger ten times larger than you needed, it would just
>> mean your thermostat would regulate the coolant flow slower so that the
>> operating temperature would still be at the thermostat temperature.  With
>> the reduced flow from a very large heat exchanger, the flow would be slowed
>> to a trickle but the engine would still operate at the correct temperature.
>> 
>> Another plus of an oversize heat exchanger is that it gives a margin of
>> safety in case you pick up some debris causing a reduction of cooling
>> efficiency.  The little 2" heat exchanger that came with the 5424 had
>> absolutely no reserve cooling capacity at full throttle, especially in
>> tropical waters.  Add debris restriction and you have a meltdown, even at
>> moderate speeds.
>> 
>> Tom Troncalli
>> 
>> 
>> 
>> 
>>> [Original Message]
>>> From: Les <hlhowell at pacbell.net>
>>> To: <tdtron at earthlink.net>; Catalina 38 Listserve
>> <listserve at catalina38.org>
>>> Date: 9/1/2009 8:43:19 PM
>>> Subject: Re: [C38] engine temp
>>> 
>>> Hi, everyone,
>>> 
>>> I don't want to appear stupid, but I am.
>>> 
>>> Diesel engines are basically heat engines.  Most are designed to run at
>>> some temperature range.  If they don't get to that range, they become
>>> very "dirty", with carbon and so forth, including poor combustion and
>>> greater nasty air products.  Does anyone have any information about what
>>> the "design" temp was for the original engines (I have an XP-25B in JACE
>>> now and it came with a larger heat exchanger, but that is no indication,
>>> as the engines internals will determine how much cooling is right.)  If
>>> the thermostat is working right, the engine should maintain the right
>>> temperature I think, but I don't know for sure.  The mechanical
>>> thermostats are in essence a two element spring that holds them closed,
>>> with a waxy cap that will solidify when the engine is cold to keep it
>>> shut until the engine warms up enough to run right.  These thermostats
>>> are really simple, but a vital piece of equipment for a diesel.
>>> 
>>> Regards,
>>> Les H
>>> On Mon, 2009-08-31 at 08:22 -0400, Tom T. wrote:
>>>>  
>>>> Ditto,
>>>>  
>>>> This sounds like my own experience.  That little original 2" heat
>>>> exchanger has to go to the Davy Jones locker for good!
>>>>  
>>>> Tom Troncalli
>>>> Renata #95 
>>>> 
>>>>  
>>>>         ----- Original Message -----
>>>>         From: Steve Smolinske
>>>>         To: Catalina 38 Listserve
>>>>         Sent: 8/31/2009 2:33:21 AM
>>>>         Subject: [C38] engine temp
>>>>         
>>>>         
>>>>         fyi
>>>>          
>>>>         as a follow up to earlier discussions on engine cooling, I
>>>>         replaced the 2" x 16" heat exchanger with a 3 x17 and dropped
>>>>         30 degrees off of my normal operating temp.  went from 190 to
>>>>         160 under way. With the larger exchanger I was also able to
>>>>         step up to 5/8 from 1/2 hose from the raw water pump to the
>>>>         exchanger.  Im amazed at how much smoother, quieter and less
>>>>         labored the engine sounds now.
>>>>          
>>>>         Steve
>>>> _______________________________________________
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>> 
>> 
>> 
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