[C38] Water Heater Plumbing

[Tom T.]

Hello,
You didn't say which engine you have but if you have the Universal 5424
24hp, it was equipped with a heat exchanger too small for the application
and the mounts to the bell housing tend to fatigue crack and fail
eventually.

After you fill any properly installed cooling system, it should naturally
"burp" any trapped air bubbles which is why you will need to add coolant at
least once after you refill the system.  If any portion of the system is
too mounted too high, as in a heat exchanger mounted to the top of the
engine compartment or a hot water heater mounted in the sail locker, the
system may never burp properly.  The highest point should be the filler
neck on the exhaust manifold.

I upgraded my cooling system with an expansion tank like modern cars have
so my system is "self burping."

There are many tricks to keep the Universal diesels cooler but the real
culprit in my opinion to the cooling problems of the early Universal 24hp
diesels is the heat exchanger.

Tom Troncalli




> [Original Message]
> From: <david at dlrfilms.com>
> To: Catalina 38 Listserve <listserve at catalina38.org>
> Date: 8/20/2009 10:13:26 AM
> Subject: Re: [C38] Water Heater Plumbing
>
>
> > After years of chronic engine heating problems, I asked this C-38 forum
> > for suggestions.
>
> I guess it's my turn.
>
> We had now heating problems when we bought the boat, but last Summer
> started to get overheat alarms.
>
> Simply cracking open the system to check this and that seemed to clear it,
> so I have (hopefully) deduced that it is an "air-lock" problem.
>
> But the overheats have gotten more frequent and are less reliably cleared
> by cracking open the system.
>
> Our most recent fix it to take the hot water heater out of the loop, which
> works, but I can still see the air-lock forming, but without the hot water
> heater in the system there seems to be enough circulation pressure to push
> past it.
>
> Because if the deteriorating nature of the problem I am wondering if the
> freshwater impellor might be damaged, but when I start the engine with the
> cap off the coolant tank, I can see (what appears to be) vigorous flow.
>
> It also seems like maybe the cap, which is spring-loaded and leads off to
> the overflow tank might not be working right. When the air-lock forms it
> pushes the coolant back down the tube, but my intuition is that this
> should function more like an air-release valve. But I'm not an engine guy
> in any way, so not knowing what it's supposed to do, I don't know whether
> or not it's working right.
>
> I'm half hoping the whole thing will overheat and seize so I can put in an
> electric drive.
>
> Help?
>
>
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