[C38] Overheating issue

Fri Jul 11 14:59:57 EDT 2014

Michael, when my water heater is hooked up my boat runs hot, about 210, and cooks all the food in the ice box.  However, when I disconnect the water heater the engine runs at 180 as it should and doesn't effect the ice box.  I too have heard these engines run on the hot side, but I doubt you had problems all these years and are just now bringing it up.  So what changed.  Is you inline water intake filter partially plugged?  Is your under boat intake partially plugged.  Do you have a freeze plug leaking.  Is there another leak in the cooling system allowing the engine coolant to leak out.  If the closed system has a leak, the coolant boils at a lower temperature.  

Just a few thoughts
Kerry Grimes
Little Breeze, 139

Loyalty above all else, except Honor.  

----- Reply message -----
From: "Max Soto" <maxsoto at gmail.com>
To: "Catalina 38 Listserve" <listserve at catalina38.org>
Subject: [C38] Overheating issue
Date: Fri, Jul 11, 2014 10:20
Michael, I don't have a water heater on my boat. As a fact, you might disconnect it while you find the problem.  You'll have less thing to check for..With a blown gasket you won't immediately see oil mixing with water.  It takes a while ( if a cylinder is joined with a coolant conduit) , unless the coolant and oil conduits get joined.  

Max Soto +506-8312-1367Alajuela, Costa Rica 
On 11/07/2014, at 11:12, Michael de lisle <krazymiked at gmail.com> wrote:

Thank you for your input guys. My boat is hull #240 and has the Universal M3 (5424) diesel. I just installed a brand new raw water pump two months ago and had plenty of flow in the exhaust exiting the boat. I thought about a blown head gasket but there is nothing mixing with the oil to indicate that this is the issue. As for the bracket, I am taking it to a very reputable welding/fabrication shop here and having them fab up a new one that will be a bit beefier. And I can not afford a new exchanger just yet but will be upgrading to the three inch when I do. How is your plumbing for the hot water tank mounted? Mine was strapped to the exchanger with a couple of radiator hose clamps. 

On Fri, Jul 11, 2014 at 10:02 AM, Max Soto <maxsoto at gmail.com> wrote:

The heat exchanger is definitely not good enough for the 5424, but if it has been working for some years, and suddenly the engine overheats like that, that is weird.

The engine could run perfectly without a thermostat. Mine has been like that for more than twelve years.
An air bubble might be the issue, but is weird that it develops out of the sudden, since it usually happens when you are filling an empty engine with coolant.

You haven't mentioned anything about the raw water system.. Is it working as it should???
A blown head gasket should be taken in consideration.  A compression test will tell the truth.  And also, a  very bad coolant cap failure might have some effect like that

Just my two cents!
Max Soto
+506-8312-1367
Alajuela, Costa Rica

> On 10/07/2014, at 22:36, Michael de lisle <krazymiked at gmail.com> wrote:
>
> So I am completely stumped and need your input.
>

> This all started when my boat overheated and boiled off all the water in the manifold filling the cabin with white smoke (steam). We got her back to the dock under sail and my initial thought was a plugged heat exchanger. On the trip back I had pulled the thermostat to check it and gave it the boil test where everything worked as it should. As a precaution I left the thermostat out to let the engine run cool but it was still getting hot.

>
>  When we got back to the dock and with the fresh water circuit still in tack I opened the bleed off valves and noticed that the fresh water I had added to the manifold was not mixing with the coolant at the bottom bleed off valve.

>
> When I got down inside I found the valves for the hot water tank strapped to the heat exchanger (HX) and the bracket that supports the HX snapped off at the bolts and the whole mess sitting atop the transmission housing.

>
> I pulled all the hoses and the HX plus hot water tank plumbing out and found that the HX was actually looking pretty good. I flushed the engine with the hoses removed and it was flowing through all the ports with out a problem. I soaked the HX overnight anyways in a mix of muriatic acid and water since I had it out and have yet to reinstall.

>
> When explaining all of this to my local mechanic he suggested that the likely problem was the fresh water pump mounted on the front of the engine. Tonight I pulled the the fresh water pump from the block and found absolutely no issues with it. No wobbles, no wear, no goop or corrosion.

>
> So whats the problem???
>
> Tomorrow I am taking the HX and the pump to the shop to have them inspected. I am also going to double check the block with a hose to make sure all the ports are open and free flowing. Once I get a new bracket fabricated I am reinstalling everything with new hoses.

>
> Has anyone got any advice as  where else I should maybe check before putting everything back together?
>
> I have not ruled out an air lock from low coolant in the system but won't know if that was the issue until reinstalling everything.

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