Water pumps

[Lingen]

A query; With an engine driven water pump, which is after all what virtually every car on the planet still has today, when the engine fires up the water within it will immediately circulate, and evenly bring the temperature of the block and head(s) up to the temperature at which the thermostat starts to open. This allows, slowly at first, the cold water in the radiator to be mixed with the hot water in the engine. When it has
all reached the designed temperature, the thermostat will continue to constantly regulate the flow of coolant, depending on how much heat the engine is generating, keeping it at the correct temperature.
This constant flow round the system ensures that the expansion of the engine is steady and even one, which is all the more important when you have a steel block and an alloy head with their different rates of expansion, which the head gasket has to cope with.
If you have an electric pump which is pulsing on and off every 20 seconds or more, doesn't this create constant contraction and expansion of the block and head(s) as the temperature fluctuates?
If a choice has been made to have an electric pump, why isn't it set to run constantly at an adequate speed to do its job, and the temperature regulation not left with the thermostat which will do it so much more accurately?
Off you go..
Mike.

[bullstarz]

The advice with the EWP is to remove the thermostat as the way the pump works, the pulsing, apparently does the same thing. A mechanical water pump is similar to the viscus fan in the fact its a compromise, Where the electric pumps and fans are designed to work 100% or nothing either on or off. That way when you need them most say in traffic and the engine isnt revving high they will work at 100%. When the car is moving and engine speed is high they dont sap power if there not needed.

Another advantage is that they will work while the engine isnt running. Mine will run when the ignition is off until the coolant reaches 79 deg c to prevent any localised heat damaging the engine.

How well mine works I'm not too sure as Ive put another radiator behind the back seat to keep the engine cool. The only thing i have noticed is that the coolant seems to be same temp throughout the system with not a lot of difference between the top and bottom of the radiators. The engine warms up evenly and just as quick until it gets to 65 deg C then it will slowly rise to 85.

When the engine gets hot and the fans kick in its now a lot quicker to cool the engine

[wilf]

Many replica Cobra builders are using these pumps. Big block Ford V8s are notoriously difficult to cool in these cars, the electric pumps help. Bearing in mind that a decent side oiler 427 V8 will set you back around $25000, and originals are becoming "unobtainable", few people would risk those engines with unproven tech. Good enough for them, should equate to good enough for a TV8

[flying farmer]

A query; With an engine driven water pump, which is after all what virtually every car on the planet still has today, when the engine fires up the water within it will immediately circulate, and evenly bring the temperature of the block and head(s) up to the temperature at which the thermostat starts to open. This allows, slowly at first, the cold water in the radiator to be mixed with the hot water in the engine. When it has
all reached the designed temperature, the thermostat will continue to constantly regulate the flow of coolant, depending on how much heat the engine is generating, keeping it at the correct temperature.
This constant flow round the system ensures that the expansion of the engine is steady and even one, which is all the more important when you have a steel block and an alloy head with their different rates of expansion, which the head gasket has to cope with.
If you have an electric pump which is pulsing on and off every 20 seconds or more, doesn't this create constant contraction and expansion of the block and head(s) as the temperature fluctuates?
If a choice has been made to have an electric pump, why isn't it set to run constantly at an adequate speed to do its job, and the temperature regulation not left with the thermostat which will do it so much more accurately?
Off you go..
Mike.

Here is my take on the electric pump situation.
Firstly I agree with all the above.
Secondly, my electric pump is set up to run constantly at a slow speed which is adequate to cool the engine even under track day conditions with the temperature being controlled by a thermostat.

How have I done it?

Very simple, fit a Davies Craig electric pump wired direct to the ignition with the supply voltage dropped using a resistor with the plumbing sorted out appropriately.

My first fit of an electric pump was on a Dolomite Sprint engine that had suffered water pump tooth failure. Wanting to do the job on the cheap I bought a pump by itself and used a ceramic ignition ballast resistor to drop the voltage with the intention of dropping pump speed and prolonging its life.

This original pump is now on its third engine as various projects have come and gone so pump life is obviously not a problem.

I did once buy a complete Davies Craig pump and controller kit second hand off ebay for just the price of a pump and fitted that to a Rover V8. To be honest I was completely under whelmed by the whole set up.
Firstly, in cold weather the heater output was dreadful,

Secondly, at night with the lights on and in traffic the alternator output voltage drops sufficiently to put the controller into fault mode so it pumps constantly at full speed over cooling the engine to the point where ice would form on the inside of the screen in icy weather.

Thirdly the regular flat out pumping would drain the battery to the point where I had to put the battery on charge on a weekly basis or risk it not starting in the mornings.

In the end I got fed up with the controller and replaced it with a ballast resistor (mk1 Stag type), refitted the thermostat, and cured all its shortcomings.

I have only once had a problem with this set up on the Stag. I had placed the resistor low down on the chassis rail where it obviously got wet regularly and eventually failed due to corrosion. Fortunately I had the forethought to use a piggy back connector on one end of the resistor so when the temperature gauge went into orbit I was able to swap the live wire to bypass the resistor. The replacement resistor has been moved higher up away from road spray.

The pump on my K reg Stag is placed low down on the left hand side of the engine. It is supported by a bracket from the lower front timing chain cover so the bottom of it is just above the bottom of the suspension cross member, unfortunately I don't have any pictures but I could take some tomorrow

Neil

[jbuckl]

Pm’d 4x4

[flying farmer]

Some pictures of my electric water pump installation, not the easiest thing to photograph.