Tell me why my engine will explode (aftermarket freshwater cooling)

[sv_isara]

Hey all, well I have a job (business) lined up and thus another boat that I'll be using a bit here in the SF Bay. It's a Catalina 30 with a rebuilt (5 years ago) Universal 5411 diesel. Without getting into the pros and cons of whether to convert (I will, that's been decided), I'd like your input on whether this system will work or not. Trying to keep it very simple.

See my diagram and let me know if you think something will explode, or my engine will run cool, or too hot, or both. Currently it pegs pretty reliably (from my little experience) at 150 deg F.

A few notes:
Coolant pump is electric, which I don't like but I don't see any viable power takeoffs available for the 5411. Would love to know if that's wrong.
Raw water exiting exhaust will vary based solely on engine RPM, instead of as stock from *both* engine temp *and* engine rpm.
Coolant circulation speed will remain constant throughout RPM and temperature and will be preset with a PWM controller.

[hlev00]

Maybe it is my lack of familiarity with Universal specifics but your post to me is clear as mud as to what exactly your asking for and what you are converting.

[skipperpete]

The water pump">raw water pump would be better placed just after the sea strainer and supplying water under pressure to the heat exchanger rather than being the last component before the injection elbow

[sv_isara]

Originally Posted by hlev00

Maybe it is my lack of familiarity with Universal specifics but your post to me is clear as mud as to what exactly your asking for and what you are converting.

Thanks for letting me know.

This engine stock is saltwater cooled. I am converting it to using a heat exchanger and coolant.

[SailingHarmonie]

A couple comments.

No fresh water cooled engine adjusts raw water flow based on engine temp. They all use a thermostat in the fresh water system to control the flow through the heat exchanger. You need to be sure the current thermostat will direct water flow correctly in the new plumbing.

Fresh water engines all run at a higher temperature than raw water cooled ones. Salts precipitate out of seawater if heated too high. Diesels run more efficiently and last longer at higher temperatures. Typically fresh water cooled engines run at 180F, while seawater cooled engines are limited to 150F.

You did not mention the kind of pump you will be using. For many reasons you MUST use a positive displacement pump, not a centrifugal one. It must be self priming even if full of air.

You need a foolproof way to be 100% sure the electric raw water feed pump can NEVER run if the engine is not turning.

There are many engineering details here. It is not a project to under take lightly.

[Fore and Aft]

Isara save yourself the trouble of mucking around with an old engine and just make it freshwater flush. Some of my fussier clients have a seacock on the engine that can be plugged into a dock tap or water tank. Then at the end of the day they turn off the raw water and flush the engine with fresh water.
Cheers

[newhaul]

Originally Posted by sv_isara

Hey all, well I have a job (business) lined up and thus another boat that I'll be using a bit here in the SF Bay. It's a Catalina 30 with a rebuilt (5 years ago) Universal 5411 diesel. Without getting into the pros and cons of whether to convert (I will, that's been decided), I'd like your input on whether this system will work or not. Trying to keep it very simple.

See my diagram and let me know if you think something will explode, or my engine will run cool, or too hot, or both. Currently it pegs pretty reliably (from my little experience) at 150 deg F.

A few notes:
Coolant pump is electric, which I don't like but I don't see any viable power takeoffs available for the 5411. Would love to know if that's wrong.
Raw water exiting exhaust will vary based solely on engine RPM, instead of as stock from *both* engine temp *and* engine rpm.
Coolant circulation speed will remain constant throughout RPM and temperature and will be preset with a PWM controller.

You could always install the fwc conversion kit it's similar to the ones for the universal atomic A4 gas unit.

[JimsCAL]

I agree with newhaul. Consider one of the conversion kits for the Atomic 4. Moyer offers them as well as parts individually. Unfortunately Indigo has stopped offering theirs. They had ones with either electric or belt driven pumps. If you go electric pump, get one that's designed for continuous operation. Many are not.

[capt jgw]

The 5411 had fresh water cooling available as an option, I had one like that. The second pump was mounted to the back end of the cam shaft, opposite where the raw water pump is mounted. In the tractor version of the engine (Kubota Z500) a hydraulic pump went there. I believe you could mount a second Oberdorfer pump there instead of using an electric one.

[sv_isara]

Originally Posted by capt jgw

The 5411 had fresh water cooling available as an option, I had one like that. The second pump was mounted to the back end of the cam shaft, opposite where the raw water pump is mounted. In the tractor version of the engine (Kubota Z500) a hydraulic pump went there. I believe you could mount a second Oberdorfer pump there instead of using an electric one.

That would be much better. I looked for this but could not find it. I will look again

[sv_isara]

Originally Posted by SailingHarmonie

A couple comments.

No fresh water cooled engine adjusts raw water flow based on engine temp. They all use a thermostat in the fresh water system to control the flow through the heat exchanger. You need to be sure the current thermostat will direct water flow correctly in the new plumbing.

I believe I have plumbed it correctly WRT the thermostat. Currently, when cold it recirculates water from the engine back to before the raw water pump. In my design, the coolant does that same thing.

Fresh water engines all run at a higher temperature than raw water cooled ones. Salts precipitate out of seawater if heated too high. Diesels run more efficiently and last longer at higher temperatures. Typically fresh water cooled engines run at 180F, while seawater cooled engines are limited to 150F.

Does anyone know the risks of running the 5411 hotter? 150 degrees did seem pretty cool to me but it makes sense as to why. Wonder if gaskets etc are rated for the higher temperature.

You did not mention the kind of pump you will be using. For many reasons you MUST use a positive displacement pump, not a centrifugal one. It must be self priming even if full of air.

You need a foolproof way to be 100% sure the electric raw water feed pump can NEVER run if the engine is not turning...

I don't believe this will be an issue w/ my initial idea of thw *coolant* pump being electric. Raw water still using the same impeller as before. Coolant pump should remain primed always.

Thank you for your input

[Madehn]

i did something similar with my generator- took engine driven pump out and put in an electric pump driven off the 110v side of the genny. Works fine- get pump of correct capacity- be sure it cannot run without the engine running and be sure it is always primed ( putting next to seacock is fine ).
For my usage a centrifugal pump worked fine not sure why you would need a positive displacement pump if it is plumbed below the waterline so it is always primed.

[newhaul]

Originally Posted by sv_isara

I believe I have plumbed it correctly WRT the thermostat. Currently, when cold it recirculates water from the engine back to before the raw water pump. In my design, the coolant does that same thing.


Does anyone know the risks of running the 5411 hotter? 150 degrees did seem pretty cool to me but it makes sense as to why. Wonder if gaskets etc are rated for the higher temperature.



I don't believe this will be an issue w/ my initial idea of thw *coolant* pump being electric. Raw water still using the same impeller as before. Coolant pump should remain primed always.

Thank you for your input

It's a farm tractor motor designed for freshwater cooling and running hotter we r so I don't see an issue that way

[805marinemechan]

i had a client about 4 years back that had 3 engines that he wanted to be able to freshwater flush without ever having to enter the engine room. said he was tired at the end of his voyage and the last thing he wanted to do is go in the engine room. the only downfall is the engine and fresh water supply need to be turned off at the same time or you risk water back flowing into the engine.

[gulfislandfred]

No worries about running hotter. FWC marine engines typically use a 180 or 190 degree thermostat. As others have said, that's a Kubota engine. They're used on all kinds of tractors, excavators, etc. FWC.
(Good engine!)
If you can drive both pumps off the engine, it makes things simpler, and more reliable, in my opinion.