[C38] Heat Exchanger?!

[tdtron at earthlink.net]

This forum has talked about heat exchangers quite a lot in the last few
years. One aspect we may have not dwelled enough on is routing of the water
hoses to the exchanger.

A heat exchanger should have reverse flow for maximum efficiency.  This
means the raw cooling water goes in the opposite direction through the
exchanger than the direction of the coolant.

If both the coolant and raw cooling water flow in the same direction
through the exchanger, the waters will average in temperature.  If the
engine is 200f and the raw water is 80f, the return water to the engine
will be around 140f.

If the waters are in opposite directions, the raw water discharge will be
much hotter than the average of the two waters.  The hotter the better. 
The coolant returning to the engine will be much cooler than the average
temps.

I have seen several boats that suffered from overheating when the only
thing required to remedy the problem was to either reverse the coolant
hoses or reverse the raw water hoses to accomplish reverse flow.

Tom Troncalli
Resident Nerd





> [Original Message]
> From: <david at dlrfilms.com>
> To: <listserve at catalina38.org>
> Date: 7/2/2011 3:45:38 AM
> Subject: [C38] Heat Exchanger?!
>
> So for whatever reason I decided I'd take apart the heat exchanger and see
> if it was clogger or rotted out or whatever.
>
> When I opened it up, the gasket was encrusted and so deformed it looked
> like a custom made gasket for the piece.
>
> Took it home. Boiled it in vinegar. Rinsed. Got a new gasket, hooked all
> the hoses back up, fired up the engine and conservatively I'd say at least
> 4 times the amount of water was coming out the back end of the boat.
>
> Before the tear down I did a cold-start log of the temperature climb.
> After putting it all back together (thermostat is still out) it was
> unchanged at 130 after 20 minute. So later today I'll to the same and see
> if there's any change.
>
> THEORY:
>
> I think I did have a bubble problem. We be puttering across the lake,
> engine on only a few minutes then *bam* the temp would suddenly climb.
> Shut down, engine still cool, open the pressure cap, scratch head. Resolve
> to never use engine ever again. I think (hope!) all the flushing,
> cleaning, rinsing fixed that.
>
> Meanwhile I think the heat exchanger performance was degrading. So instead
> of sudden overheats, I was getting about an 60-70 minutes from dead cold
> to 190.
>
> Anyway. We'll see what happens later today.
>
> Then on to the leaky injector...
>
>
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