[C38] engine temp

[Les]

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
> > > _______________________________________________
> > > Listserve mailing list
> > > Listserve at catalina38.org
> > > http://catalina38.org/mailman/listinfo/listserve_catalina38.org
> 
> 
> 
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