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Old 22-02-2010, 13:38   #1
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Universal 5411 - Cooling System Failure and Fresh Water Conversion

This will probably be of interest to anyone with a Universal 5411 in their boat.

While on a cruise this past summer to Maine the Universal 5411 in my Catalina 27 started pumping lots of seawater out of the timing hole in the bell housing. I was able to fix that quickly enough that we were able to continue with the cruise. I described that experience in some detail elsewhere on this forum - Gord...Need Help 5411/z500.

In light of this experience we have decided to convert this engine to freshwater cooling to hopefully avoid this problem in the future.

While researching this I spoke with a mechanic in a large marine engine shop in Mass. He said that given the freeze plug failure that I described in the post above, there is likely at least one more ticking time bomb in my engine. It is a steel plate covering a casting hole on the front of the engine under the gear cover that is likely to corrode. So last weekend I went in and had a look. It took a couple of hours to remove the gear cover and at first this steel plate looked fine. But when I removed it, sea water on the inside had corroded the underside to the point where it is concave on the inner surface almost out to the edge. It was in fact close to failure. Had it failed we would be injecting sea water into the timing gears and the engine would likely fail in short order.

I have a machinist buddy that can make me a new cover plate out of bronze or stainless steel and the gaskets and seal that I need to put it back together are Kubota industrial engine parts I can get quickly here in town, so that part of the job will not be too bad.

Conversion to fresh water cooling is maybe another matter. I originally thought I would install another neoprene impeller pump much like my existing raw water pump to pump the antifreeze. This looked very possible since the rear facing end of the shaft that drives the raw water pump is accessible and only covered by a steel plate and there is room for a pump. (This is where the hydraulic pump would be located if this engine was installed in a tractor instead of a boat.) When I did the research, it seems that neoprene impellers are only good to 140 degrees and it would tend to fail frequently if used to pump antifreeze. Talking to a pump specialist at Depco leads me to think I should use an electric circulating pump for the antifreeze. This would be a much easier installation. The difference with an electrical pump is that I have added another point of failure and the circulation and therefore the cooling is stable at all engine RPM instead of increasing as engine RPM rises.

Anybody think this is a problem? Or maybe you have other suggestions? Or maybe someone has already done this and I can learn from their experiences. A few 5411s apparently were installed by the boat manufacturer with fresh water cooling at the factory. I wonder how they are set up? Anybody have knowledge or experience to share?

Paul Meyer
New Brunswick
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Old 22-02-2010, 14:02   #2
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try posting at Someone there has likely done the conversion.
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Old 02-05-2015, 07:35   #3
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Re: Universal 5411 - Cooling System Failure and Fresh Water Conversion

Old post, I know, for info only
There was an aftermarket freshwater kit for the 5411, it was just as you described, a Sherwood pump mounted where the tractor hydraulic pump would go, and a vertical heat exchanger with a radiator cap on top. The HX on mine developed a crack so I took the Sherwood off and went back to raw water cooling. The Sherwood is a pretty crappy pump anyway.
FWI, access to the Sherwood at the rear of the fuel cam housing is very limited, you would have to remove the pump to change the impeller and as your pumping hot A/F you'll be doing this often. An electric pump may be a better option. The HX or one like it may still be available, I don't know who made it and have not tried to locate one.
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cooling, engine cooling water

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