Electric water cooling pump?

[Stuart Lewis]

Hi

 

I have had issues with my secondary water pump, a Johnson pump driven by the engine, pulling water from the skin tank.

The seals were leaking water into the engine, and the bearings were completly shot aswell.

I have had a an order placed for a new pump, but this is taking sooo long and it is very expensive - we rerally need to get out cruising ASAP!!

 

So my question is: can I do without this pump? or can I use a 12v electric pump in its place.

has anyone done this before?

and can anyone shed any light on a suitable flow rate as I guess the Johnson one wold have varied its flow depending on the engine speed, but the electric one would be constant.

 

My engine is a Vetus M4.14.

 

Thank you

Stuart

 

 

 

 

[b0atman]

question if you had been with RCR would this only cost you £50

[Iain_S]

The Vetus 4.17 in Copperkins runs OK with the engine's own water pump. Water goes from top of engine to heat exchanger (core removed) then to top of skin tank and return to engine from bottom of skin tank.

 

Does yours have a seperate secondary circuit, or is the Johnston pump in series with the engine water pump?

 

Iain

[by'eck]

The second pump and cooling system is designed for boats that take raw water from outside and cool the engine via a heat exchanger which takes the heat from the engines own closed circuit cooling system. On such engines the waste raw water is usually injected into the exhaust system to cool it (wet exhaust), such that you get exhaust gases and water spluttering out.

 

Since your secondary cooling system is closed circuit itself via skin tank there is not much point in having one closed circuit system cooling another. You could just remove the heat exchanger and engine connections and plumb them directly to the skin tank. If there is no need for a wet exhaust you could bin the secondary Johnson pump as well.

[dor]

Don't really see why the second pump is there with a Vetus 4.14. Normal installation is using the engine water pump, circulating water through the skin tank via the exhaust manifold header tank, with an expansion tank coming from a connection on top of the thermostat housing.

 

If you have a skin tank, which according to your original post you do, I can't see any benefit in having the second circuit. Cooling will be more efficient connected directly to the skin tank.

[Stuart Lewis]

Right, my setup is as Iain says

 

Water goes from top of engine to heat exchanger (core removed) then to top of skin tank and return to engine from bottom of skin tank.

 

Our Johnson pump was in-line, between the bottom of the skin tank and the engine water pump.

I had assumed it was required to help pull the water out of the skin tank.

 

So (with a big smile on my face) I shall phone and cancel the order tommorow and fabricate a plate to cover the hole in the engine left by the removal of Johnson pump

 

Thank you all for your info, I should have done this earlier - quite new to narrowboating and finding it a steep learning curve!!

 

Stuart

[Tony Brooks]

Please do not cancel the order until you are sure the thing is plumbed as you say. If it is then the engine fitter was a bit of a Yahh-hee merchant and should have known better. I would expect it to be as By'eck describes (again in my view a bit of complication for no good reason save its a Vetus) and although simple to convert to a single pump system if you know what you are doing it will involve a degree of re-piping and blocking two holes. The hoses on the raw water system are also usually a bit narrow for my liking when using the engine water pump. Think car radiator sized hoses. Once you convert it it should work fine and have less to go wrong.

[Redeye]

If you want an electric water pump try a Davies Craig available from Demon Tweeks. My engine being originally raw water cooled is cooled by a heat exchanger. The Davies Craig pump circulates the water through the skin tanks and the heat exchanger.

 

The system is easy to fit and works really well.

 

Andy

[flatplane8]

If you want an electric water pump try a Davies Craig available from Demon Tweeks. My engine being originally raw water cooled is cooled by a heat exchanger. The Davies Craig pump circulates the water through the skin tanks and the heat exchanger.

 

The system is easy to fit and works really well.

 

Andy

I've also fitted one of these to a lister JP3 to enable heat exchanger cooling. What engine is yours fitted on?

[Chalky]

Secondary water pumps are commonly fitted to high performance cars such as Jaguars and BMWs to help with cooling. The typical usage is to maintain coolant circulation if the ignition is turned off straight after after a high speed run (e.g. pull into services on motorway...). They usually have brushless motors and the impeller is magnetically coupled to the motor so there's no seals to leak. If you do decide you need one in a hurry a trip to the scrap yard might allow you to source one cheaply. The hose connections are small. I use one to pump the water round the heating rads on my boat and the rubber hose connects directly to the 22 mm heating pipes. (for the heating system I PWM it to slow it down since it pumps too much water is powered directly)