seemed like a good idea @ the time...

[kiwiSteve]

You know how you come up with brilliant ideas that may or may not turn out to be so brilliant after all...

 

When I set up my BMC marine engine i was worried using a closed cooling system might lead to cooling water trapped in the manifold boiling and causing a fuss, so as I had a few parts lying round and came up with this bright idea... just wondering what people think of the theory if boiling to steam is possible inside the manifold water jacket of the closed circuit cooling system or will the thermostat open before any problem...

 

[blackrose]

I don't really understand the basic premise of your post. Thousands of canal boats have closed loop cooling systems and as long as the heat exchanger (skin tank) is large enough and is properly made then the coolant shouldn't overheat. Unless your engine is particularly large or you don't have enough space along the swims to fit adequately sized skin tanks then it sounds like you're trying to find a solution to a problem that doesn't exist.

 

The other possibility of course is that I've misunderstood your post and you're talking about something else completely, in which case my apologies.

Edited February 15 by blackrose

[kiwiSteve]

oh ok... you are probably right... "trying to find a solution to a problem that doesn't exist."... But when the thermostat is shut when the engine is cold there is no water movement through the manifold until the thermostat opens @88 degrees... I guess the water in the manifold wont boil while its waiting to heat up and the thermostat to open so no worries then...(even though theres not a lot of water in there) I was worried that, that small amount may heat up quicker than the engine, boil and turn to steam and the pressure might pop a hole in the manifold or something nasty... anyway just a thought...

 

 

Edited February 15 by kiwiSteve

[Tony Brooks]

Most thermostats have a small hole in them to allow air to get past when filling the engine so there will always be some water movement when the water pump is running. That seems to be enough flow to prevent any problems in all the keel/tank cooled installations I have seen. However, what you have drawn is pretty much what fully raw water cooled automotive based engines like the BMC 1.5s are plumbed so water is directed to the manifold and exhaust when the thermostat is closed.

[kiwiSteve]

1 hour ago, Tony Brooks said:

Most thermostats have a small hole in them to allow air to get past when filling the engine so there will always be some water movement when the water pump is running. That seems to be enough flow to prevent any problems in all the keel/tank cooled installations I have seen. 

 

ok, that makes sense now i think about it, theres got to be some sort of flow just to keep things going in the right direction... 

 

 

[Tony Brooks]

Just now, kiwiSteve said:

 

ok, that makes sense now i think about it, theres got to be some sort of flow just to keep things going in the right direction... 

 

 

 

For completeness many, but not all engines, have a small bypass port that keeps coolant circulating around the engine with the thermostat closed, but that will not affect your "problem". Also, in the majority of cases, the calorifier coil acts in a similar way to allow circulation through the engine. If you have a calorifier then by routing the return via the manifold would save the need for the relief valve.

[blackrose]

You're much better off sticking to a closed loop cooling system if you can. You basically fill it up and forget about it until it's time to change the coolant. In comparison both direct and indirect raw water cooling systems are the subject of frequent problems on the inland waterways mainly because of blockages of intakes, mud boxes, etc.

 

Ok perhaps that's just basic maintenance rather than a problem as such, but that's my point really. Once a closed loop system is filled and bled then apart from the odd top up you shouldn't have to touch it until the coolant needs changing, and in the case of most red antifreeze that's 5 years. Or you can just top up with an Ankorsol anti-corrosive solution and make it last even longer. With raw water cooling you've got to clean intakes & mud boxes and winterise it every year to make sure your raw water pipework doesn't freeze and burst.