Radiator cooled engine

[maxwin]

Goodday,


( Longtime member but first post now ), Restoring a 1985 Fletcher Arrowbolt 21 a the moment, got everything almost out, some deck was in a bad shape.
However the stringers and the stern are in a good shape. ( will post some pics later )

Engine is a 5.7 mercruiser with some rust on the outside, but engine runs fine, have some small problems but easy to solve.

As the boat was always running in raw seawater the risers and part of the exhaust was eated by the seawater.

So i was thinking about changing the whole cooling system with a closed coolingsystem, but not with a tradicional heat exchanger, ( as it will take some time to fabricate also)

But with a aircooled radiator or radiators with some electric fans running on it.

Also leaving the engine "room" open on the top. as the exhaust wont be cooled by water also, more or less as you see on some jetboats..

I have some ideas where to put the radiator or radiators,

Reading around the net but not much info found, so asking here, any ideas, and pros and cons about this idea..


Tnx

 

[GA_Boater]

Welcome to posting after almost 7 years.

In my opinion - Leave the radiator in the truck and keep the original cooling. Unless you take the motor out and hot tank the block and heads, rust and scale will plug the radiator. Air cooling the radiator might not work all that great, anyway.

How do you plan on routing the exhaust out of the boat? Again, I would leave it as designed.

 

[alldodge]

Electric fans in an engine room, don't really like the sound of that, don't know of anyone which makes a fan of the type picturing being ignition protected and meeting J1171 requirements.

Dry exhaust is not an issue except those things that may touch it.

 

[maxwin]

Tnx for the quick response,

In the engine is no rust or dirt, cleaned and flushed with MB engine flush, as we also use you for some engines if they are very dirty or when overhauled.

Engine runs fine on testbench.. so the rust wont be the issue,

For the radiator must not be the standard car radiators, we also have here some big ones for generators. the fans for the cooling are closed types and not with carbon brushes as on the automotive systems.

I was only wondering if someone has done a conversion as this.. as the original with all the impeller trouble, leaks, Y pipes, overheating, rotten risers,
On the exhaust side of the engine bad flow backpressure.

I have almost all the stuff here in the yard available so enough material to experiment.

 

[Bt Doctur]

How are you planning to cool and direct the exaust?

 

[Scott Danforth]

Electric fans will not cool your motor ( they will help, however will not cool the load of a marine motor under load). Average truck radiator is good for 30 go max ( that's all your truck uses to go down the road pulling a trailer).

Dry exhaust will cause a fire. The best marine cooling system is a heat exchanger.

 

[thumpar]

If this was a good idea the manufacturers would have done it a long time ago. Even on heat exchanger closed cooling change over it is not recommended after 100 hours because of the buildup.

 

[Bondo]

Reading around the net but not much info found, so asking here, any ideas, and pros and cons about this idea..

Ayuh,.... Welcome Aboard,.... There's a reason ya can't find any info on the web 'bout it,.....

It's a No Go, Bad idea, No pro's, All con's,...
Just a few mentioned above,.....

 

[maxwin]

If this was a good idea the manufacturers would have done it a long time ago. Even on heat exchanger closed cooling change over it is not recommended after 100 hours because of the buildup.

Thats not always tru, modifying and tuning can give better results, and in terms of boatbuilding as i see how some manufacturers making there products...

 

[maxwin]

Ok clear, going to fabricate a nice big enough heatexchanger..

Years ago with a boat i modded in holland ( steel build ) engine converse, the cooling was much more easy, a steel pipe / tube around under the ship, cooling worked perfectly.

But with sportboats at high speed only the tail is in the water,

Tnx regards

 

[maxwin]

And in Holland we are making sometimes more things which are "impossible"

https://www.youtube.com/watch?v=ZeoIO89Idno and more..

 

[HT32BSX115]

going to fabricate a nice big enough heatexchanger..

You certainly CAN install a big enough AIR:Water heat exchanger on any engine and with enough airflow, it will work.

But why would you want to do that when you already have a FAR more effective heat sink? (the water you're floating in)

Liquid to liquid heat exchangers are MUCH smaller, weigh less and are far more thermodynamically efficient.

That 21ft boat is space-limited as it is.......... adding a large enough radiator with a big fan and leaving the engine compartment open (to accommodate hot, non-jacketed exhaust) will just take up room that is already in short supply. (and you're still going to have a severe fire hazard even with the open compartment)


Good luck.

Rick

 

[Bondo]

Ok clear, going to fabricate a nice big enough heatexchanger..

Years ago with a boat i modded in holland ( steel build ) engine converse, the cooling was much more easy, a steel pipe / tube around under the ship, cooling worked perfectly.

But with sportboats at high speed only the tail is in the water,

Ayuh,.... Keel Coolers are common on displacement type hulls run in saltwater,.... Even here,.....

Yer missin' one of the points,....
If yer motor has been run in the brine, the salt leaches into the iron,....
If ya switch to closed coolin',....
The salt mixes with the antifreeze, 'n ya get a gooy substance that plugs everything up,....

Only fresh new motors are candidates for closed coolin',...

 

[maxwin]

Engine is clean, this helps: MB Zitronesaure, we use it in the shop also for very dirty blocks with long time leaking heads or gaskets.. than after rebuild good as new. mostly you see the temp 5 to 10 degrees celcius less.

 

[maxwin]

No Title

Available at the MB dealers:

 

[GA_Boater]

Not to doubt your knowledge, but I don't think lemon juice is doing the job you think, Max.

 

[thumpar]

I have never understood why people come and ask a question and they argue with all the answers they get. If the original intention was to do it anyway then don't ask. There are plenty of blown up and broken boats out there from some of this experimenting.

 

[maxwin]

Its a bit stronger than lemonjuice so better don,t drink it,


"I have never understood why people come and ask a question and they argue with all the answers they get. If the original intention was to do it anyway then don't ask. There are plenty of blown up and broken boats out there from some of this experimenting""


Thats why forums are for i think, and try experimenting and innovation can lead to results.


And in my expierience is that theory and practice not always running the same.


But ok i will post the results, when the engine is running on the bench.

And have some work to do with the deck and interior.


Regards

 

[thumpar]

Its a bit stronger than lemonjuice so better don,t drink it,


"I have never understood why people come and ask a question and they argue with all the answers they get. If the original intention was to do it anyway then don't ask. There are plenty of blown up and broken boats out there from some of this experimenting""


Thats why forums are for i think, and try experimenting and innovation can lead to results.


And in my expierience is that theory and practice not always running the same.


But ok i will post the results, when the engine is running on the bench.

And have some work to do with the deck and interior.


Regards

But still, why post when you where going to do it anyway? Stay off my lakes.

 

[maxwin]

Changed for idea for intercooler, instead of air rad cooling, so..

Stay off my lakes ??what do you mean by that, friendly or as a joke i hope so..