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Running engine without glorified connected??


TandC

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Hello all.  Any advice welcome - I'm looking at a friend's boat which is in a sorry state and they need to get to a boatyard.

 

Simple question then the detail....

 

Can the hot water cylinder/ heat exchanger be removed from the circuit entirely,  and simply connect the outlet and inlet pipes on the water pump together to allow the engine to be run safely?

 

The engine is a Thornycroft, stamped on the block is  MK140. Brass plate reads Bowman. 3997KC and date stamp is 4 87.

 

There remains the connections to the skin tank - out and return. They are sound.

 

However.... the boat hasn't used the heating system for years. 

 

There was a calorifier with hot water tank / exchanger fitted but it seems to have had some of the connections just cut.... 

 

On the side and at the bottom of the cylinder is a pipe running into the boat.  I'm guessing this is the heating return? Or is that the feed?

 

Just above that on the side of the cylinder is a hose to the water pump on the engine. Guessing this is the feed from the engine into the cylinder exchanger coil? 

 

Then again on the side of the cylinder but close to the top is another pipe leading to the engine- presume this is the coil returning to the engine?

 

At the very top of the hot water cylinder is a pressure release valve. Two pipes - one has just been cut off. The other goes to the boat internal so I am guessing was a feed or the return for the boats heating.

 

 

It all feels dry.  I have no idea what's happened to the heating system inside the boat, whether it's a sealed but redundant system or what.... there is a solid fuel stove but it doesn't have a back boiler.  

 

Ultimately they need to cruise to Banbury from Oxford and back again so I just need to help them get the engine running safely without it overheating.

 

 

Any thoughts? 

 

I can add more detail and pics as and when....

 

 

Thanks

Tim

20190817_095856.jpg

Edited by TandC
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Not overly sure about what you mean by calorifier/heat exchanger. Although a calorifier does exchange heat the normal use of the term heat exchanger is something different, often inside the exhaust manifold or a operate item cooling engine or gearbox oil.

 

On the face of it without images of what pipes on the calorifier have been cut off I would suggest it would be better to simply plug the two calorifier pipes. If you don't then hot coolant can bypass the skin tank. This assumes the engine water pump has its own bypass circuit (it will be inside  where you can't see it). To be sure it may be best to join the two pipes with something like a 6mm restriction so it acts as  a bypass when the thermostat is closed..

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Ahhh sorry Tony.  Being an air cooled man these  new fangled engines are a mystery!

 

It appears that the feed and return from the engine which must go into/back the coil inside the hot water cylinder are still intact and having just taken the jubilee clip off they were still wet with coolant.

 

The hot water tank itself is dry and the only pipe that's been cut is one coming off the pressure release valve on the top.

 

If I just leave it as it is currently, the coolant is going to cicrculate through the hot water cylinder coil as normal, although as that cylinder is dry, it's not going to exchange any heat and will return to the engine.   

 

Is that Okay?  I am presuming that the cooling supplied by the skin tank provides enough cooling.

 

Currently the little coolant expansion tank is empty.  I've also lost coolant from the cylinder coil as a result of removing one of those pipes briefly. 

 

Where does the coolant running through the coil inside the hot water cylinder come from? Is that a separate closed system to the coolant in the skin tank? 

 

If I simply refill with fresh coolant through the small expansion tank, will that fill up the whole system - both topping up the coolant in the skin tank and that flowing through the hot water coil? 

 

Thanks again - noddy questions! 

 

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3 minutes ago, TandC said:

Where does the coolant running through the coil inside the hot water cylinder come from? Is that a separate closed system to the coolant in the skin tank? 

 

 

 

It comes directly from the engine.

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If the calorifier is empty of water, with just the coil inside full of coolant going too and from the engine, then there is a risk that during the run to the boat yard, the vibration could fracture the poorly supported coil. This would dump the engines coolant in to the caulifower. You could either fill the calorifier with water, leaving it open vented at the top to deal with expansion as it heats up, or take the coolant intake and outlet pipe off the calorifier and join them together. If it is dry at the moment, then it is contributing nothing to engine cooling. Even full of water it only contributes till the water inside the tank rises to engine temperature.

 

Jen

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Thanks all.  I've simply taken the cylinder out of the equation by connecting the outlet and return on the engine to each other.  

 

Having refilled with fresh coolant and run it for 15mins, at first just that hose was getting hot.  

 

Then after 5mins or so the hose to the skin tank got hot so guessing the thermostat opened and it started to cool from the skin tank.

 

Nothing went pop, although it was just idling.  Need to take it for a test run for a bit and see how that holds up.

 

It's a real dog's dinner - there are three sets of water pipes in the boat, nothing was ever removed just new plumbing installed over the top.....  originally there were three radiators running off this hot water cylinder and I think a back boiler stove too.   There is also a load of old diesel lines which look to have fed a Webasto diesel heater or some such.....

 

Anyway I just wanted to know it's not going to cook the engine.l so thanks for the reassurance.

 

The alternator has gone too so now waiting for a new one to arrive and hopefully she will be ready to limp up to Banbury.

 

Fingers crossed!

 

 

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55 minutes ago, TandC said:

Thanks all.  I've simply taken the cylinder out of the equation by connecting the outlet and return on the engine to each other.  

 

Having refilled with fresh coolant and run it for 15mins, at first just that hose was getting hot.  

 

Then after 5mins or so the hose to the skin tank got hot so guessing the thermostat opened and it started to cool from the skin tank.

 

Nothing went pop, although it was just idling.  Need to take it for a test run for a bit and see how that holds up.

 

It's a real dog's dinner - there are three sets of water pipes in the boat, nothing was ever removed just new plumbing installed over the top.....  originally there were three radiators running off this hot water cylinder and I think a back boiler stove too.   There is also a load of old diesel lines which look to have fed a Webasto diesel heater or some such.....

 

Anyway I just wanted to know it's not going to cook the engine.l so thanks for the reassurance.

 

The alternator has gone too so now waiting for a new one to arrive and hopefully she will be ready to limp up to Banbury.

 

Fingers crossed!

 

 

 

I very much doubt that although its possible. More likely the radiators were running off the stove/Webasto that also heated a coil in the calorifier. A very common arrangement.

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