Author Topic: Stw3 cooling  (Read 381 times)

Kahana2

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Stw3 cooling
« on: May 27, 2020, 08:01:53 PM »
Hi all I've got a stw3 in NZ which is now post a top end rebuild after drinking seawater running well in a yacht, I've got a few things I was hoping to understand better .

Mine is still set up with raw water cooling but have purchased a heat exchanger and header tank, looking for advice or view of a  similar set up pic to see how its been or should be done.

Thanks great to join too cheers
« Last Edit: May 27, 2020, 10:34:02 PM by Kahana2 »

cobbadog

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Re: Stw3 cooling
« Reply #1 on: May 28, 2020, 07:06:47 AM »
Welcome to the forum fella.
I understand that this came out of a yacht and was running sea water for cooling, is that right?
I see that in your picture there is a marinised style manifold on the engine now, is this your new cooling system?
What do you want to do with the engine, back into a boat or used on land and at shows or on a property?

I converted a small 3 cylinder Daihatsu engine over to run a Hamilton Jet in a mullet boat. The engine coolant went through a 4" round stainless steel tube and sea water was pumped through the inside of that big tube through some #/*" tubing to cool the engine coolant. The sea water was circulated by the Jet propulsion unit.

If you wish to run this engine on land again then it can be kept cool by running your engine coolant through a radiator, or via a large water tank similar to a 50 litre water tank and allow it to thermo syphon. In this case the bottom of the tank mush be above the engine in height.

hope this helps in some way, if not ask again.
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glort

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Re: Stw3 cooling
« Reply #2 on: May 28, 2020, 12:26:31 PM »

What sort of HE did You get, Flat plate or bar and Tube?

Does your Yacht have  Keel Cooling or anything else built in?
Easy to plumb the engine into the HE but you then have to dump that heat.  Usually a Pump is set up on the engine that sucks up the sea water, Pumps it through the HE and then overboard again.  You circulate the water through the HE and the engine and the pump uses the pickup and dump fittings you have now and just pushes the water through the HE.  The water pump on the engine Circulates the water through the block which you can fill with coolant/ inhibitor and will also need a header tank for if it does not have one.


I had a Mildly worked 308 in a Haines Hunter with a 3 Stage Hamilton on it. Great boat. I was disappointed when I finished it the thing would only run in 6" Of water. I was hoping for 4 but it was a pretty deep V. When I ordered the Hull, they stuffed up and put this huge ballast tank in the front. I refused to pay for it so they left it there.  Turned it into a 200 odd liter Fuel tank. Don't know what it actually took, never game to fill the thing right up. Never ran out of fuel on Rallies though!

I did come unstuck once At Port Stephens sand bar skimming when the thing picked up a lot of shell Grit which clagged the Tubes in the HE.
Sand was small enough to go through I guess but this Coarser grit Blocked it solid.  Was up the coast a bit from where we set out but I managed to join some hose and had direct cooling into the engine with the output  just going over the side.
 Spent some hours next day with a Piece of coat hanger wire Rodding out all the tubes. Was slow going as the shell jammed rather than just pushed out and each tube had to be done many times to break the grit up them tap and wash it out then go again.

  After that I got some fine stainless mesh and put that in the end cap where the water came in and always carried a bit of better straight wire to  clean the HE if I did get anything it as well as plenty of hose to bypass the HE if need be.  Was always a bit careful Sand bar running after that. I did clag it again but it was easy to undo the end cap, empty the grit out and put it back together and carry on.

That boat was the Pride of the Club I was in but I sold it to buy another house ( which I didn't need to do in the end   >:( ) and went to buy it back 3 years later as I really missed the thing . Rang the guy I sold it to and he said he would be prepared to sell it as he hadn't been using it. That was an understatement of the Century!  Went there and saw it in the front yard.  It was completely full of water from being in the rain Uncovered. It was Full up to the sides and the engine was obviously submerged with everything else in the Mini Swamp.  The top of the seats I could see were just destroyed, the screen was Crazed and it was just a mess. Tyres on the trailer was flat and the thing looked like it hadn't been moved since I sold it to him.
I was heartbroken and had to look at the rego numbers to make sure it was my once beautiful boat.

I didn't go to the door, just turned around, came home, had a little cry, several times over the next month I think, and that was that.

How the hell anyone could pay that much for a Boat which I kept Immaculate and under a cover in the shed and then just leave it in the open like that and let it become completely ruined is something I'll never understand and will always Haunt me.

cobbadog

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Re: Stw3 cooling
« Reply #3 on: May 28, 2020, 12:45:24 PM »
Yep, sometimes it is not worth going back in time and memories as they can be destroyed.
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Kahana2

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Re: Stw3 cooling
« Reply #4 on: May 28, 2020, 10:57:09 PM »
I picked up a smaller heat exchanger ( tube style )and top tank that had suited a 60hp diesel earlier its clean and been pressure tested etc. My little STW is still in the yacht still set up as 100% raw water cooled.
no keel cooling required just wondering if a similar set up was in place with another similar set up cheers

cobbadog

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Re: Stw3 cooling
« Reply #5 on: May 29, 2020, 07:44:50 AM »
It would be interesting to see how the narrow boats are done with the cooling of the Listers in the canals.
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Kahana2

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Re: Stw3 cooling
« Reply #6 on: July 27, 2020, 06:18:28 AM »
anyone know of any suitable belt drive circulation pumps, to pump fresh water through heat exchanges to suit listers ??

cobbadog

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Re: Stw3 cooling
« Reply #7 on: July 27, 2020, 12:27:59 PM »
Have you considered an electric pump. Far more to choose from and less expensive.
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glort

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Re: Stw3 cooling
« Reply #8 on: July 28, 2020, 01:49:32 AM »
anyone know of any suitable belt drive circulation pumps, to pump fresh water through heat exchanges to suit listers ??

The usual ones on Boats are the brass cased, rubber impeller types made by Jabsco.
Have 3 or 4 of them up the back. They come in different sizes and outputs and are not cheap but good pumps which are easily serviceable.

https://www.generalmarine.co.nz/brands/jabsco-brand/jabsco-pumps

https://www.ebay.com.au/itm/Jabsco-Engine-cooling-water-pump-3-8-bsp-10l-min-belt-or-direct-drive-51510-2001/184299575989?hash=item2ae91c5ab5:g:DbIAAOSwq7JT9oUz