[C38] Overheating issue

[Tom T.]

I don't know what engine you have but the Universal 5424 has always had 
a bad reputation for overheating.  Although a great engine, when 
Universal made the 5424 from the venerable Kubota tractor engine they 
provided a 2" heat exchanger a little too small  for the job and the 
light support bracket was prone to metal fatigue failure.

The only proven remedy I know to fix this dual problem is to upgrade the 
heat exchanger to a 3" model and provide a stronger mount for the new 
exchanger.  I made my mount from heavier steel and I used the same 
original mounting bolts on the bell housing.  I don't know if anyone 
makes a more rugged after market exchanger mount but the original mount 
has proven inadequate and prone to failure.

I have personally seen three boats of various brands with Universal 5424 
engines that had heat exchanger problems. All three had their exchangers 
broken loose and bouncing around on the bell housing making a racket.  
The only thing keeping the exchangers out of the flex coupling was the 
length of the hoses.  I think a loose exchanger is possibly a disaster 
waiting to happen.

Tom Troncalli
Previous owner of #95



On 7/11/2014 1:37 AM, Mark Lewis wrote:
>
> Had overheating also.  Make sure water exiting exhaust thru hull, so u 
> know impeller is good. Also learned engine will overheat if the 
> thermostat is removed due to a bypass circuit (counter intuitive).
>
> On Jul 10, 2014 9:36 PM, "Michael de lisle" <krazymiked at gmail.com 
> <mailto: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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