Thermostat fittings for old engines?

[Doodlebug]

Hi, I have a Ruston Hornsby 3 cylinder engine and the thermostat does not exist and so when starting there is a bypass valve that has to be opened to get it up to temp. Once up to temp (normally whilst cruising along) I have to run inside and close the bypass where the engine then runs cold until the calorifier is up to temperature. 
 

None of that seems ideal. 
 

I have been trying to find a thermostat that I can plumb in to the 22mm pipe or a BSP fitting. Does anyone know of anything suitable? 
 

On the attached picture A is the outlet from the engine. B goes towards the calorifier and C goes straight back into the engine. 
 

Many thanks. 

[Tony Brooks]

General non-Ruhton comments

 

Does C go back into the inlet side of any engine water pump. I would expect it to, so the pump can recirculate the returning water (until you close the valve). If so, be careful about what you do. On many engines this bypass is vital to stop local hotspots inside the water jacket overheating and locally boiling furring up.

 

If the Jabsco type pump is the circulating pump, then stopping it pumping water may not be a good idea in case friction allows the residual water in the pump to boil and damage the rubber impeller. I suspect there is more relevant plumbing than that shown.

 

I don't know if any hoses are involved, but some Renaults had a thermostat that fitted inside a coolant hose and secured by an external worm drive hose clip - Renault 4 I think and possibly Renault 5.

 

As far as the engine staying cold until the calorifier warms up, I don't think it is a particularly important issue, probably a more theoretical concern than a practical one. The same applies to the vast majority of boats equipped with calorifiers. Offhand, only Barrus seem to fit another "calorifier" thermostat to mitigate it. However, the calorifier feed hoses used on other boats are typically about 1/2" bore, so will restrict the flow to a degree.

 

Is this direct canal water cooled, heat exchanger cooled, or skin tank cooled, because the plumbing is likely to differ. Wet or dry exhaust.

[BEngo]

I think the Redshaws at Braunston had a separate thermostat housing for boats without one.

 

Failing that an industrial size thermostatic  mixing valve ( like the ones often fitted on a corifier but bigger)  should do the job.

 

N

[Doodlebug]

24 minutes ago, Tony Brooks said:

General non-Ruhton comments

 

Does C go back into the inlet side of any engine water pump. I would expect it to, so the pump can recirculate the returning water (until you close the valve). If so, be careful about what you do. On many engines this bypass is vital to stop local hotspots inside the water jacket overheating and locally boiling furring up.

 

If the Jabsco type pump is the circulating pump, then stopping it pumping water may not be a good idea in case friction allows the residual water in the pump to boil and damage the rubber impeller. I suspect there is more relevant plumbing than that shown.

 

I don't know if any hoses are involved, but some Renaults had a thermostat that fitted inside a coolant hose and secured by an external worm drive hose clip - Renault 4 I think and possibly Renault 5.

 

As far as the engine staying cold until the calorifier warms up, I don't think it is a particularly important issue, probably a more theoretical concern than a practical one. The same applies to the vast majority of boats equipped with calorifiers. Offhand, only Barrus seem to fit another "calorifier" thermostat to mitigate it. However, the calorifier feed hoses used on other boats are typically about 1/2" bore, so will restrict the flow to a degree.

 

Is this direct canal water cooled, heat exchanger cooled, or skin tank cooled, because the plumbing is likely to differ. Wet or dry exhaust.

C goes directly back into the engine. So at the moment the bypass valve is either on or off. 
 

As soon as the engine is up to temperature and I close the valve the smoke from the exhaust turns white showing that it is not fully heated. I am getting better at not fully closing the valve to try and get a balance but that is obviously dodgy if I make a mistake and the water boils. 
 

The pump is never prevented from pumping - it either pumps back into itself or into the calorifier and then the skin tank. 
 

many thanks. 

[Tony Brooks]

52 minutes ago, Doodlebug said:

am getting better at not fully closing the valve to try and get a balance but that is obviously dodgy if I make a mistake and the water boils. 

 

If Redshawas can't help, then I think that is the way to go. Possibly fit a temperature gauge or an overheat warning buzzer. I think that you can still get bolt on thermal switches designed to wet exhaust that would be good for a buzzer if you don't want to fit a sender into the cooling circuit or cylinder head.

[Doodlebug]

7 minutes ago, Tony Brooks said:

 

If Redshawas can't help, then I think that is the way to go. Possibly fit a temperature gauge or an overheat warning buzzer. I think that you can still get bolt on thermal switches designed to wet exhaust that would be good for a buzzer if you don't want to fit a sender into the cooling circuit or cylinder head.

Just been to redshaws and they have sorted me out with a thermostat to fit 😊 

 

thanks for all the help.