Forum:
I'm toying with the idea of an additional water pump, an electric one that comes on together with the fan, but only when engine is shut off. This should / could / might cool down the engine, instead of leaving it cooking & might help prevent gasket probs.
Has anyone actually done this or have any thoughts on it? Thanks, Paul.
Electric Pumps
BMW now fit these to their cars, i did this several years ago to a range performance engines, but it was very marginal on cooling when the engine was running, so every little helped.
On a standard engine, little would be gained; let me explain without getting too technical.
Heat soak is what it is called, basically when a vehicle is running it generates heat, while the vehicle moves, it receives air at whatever speed the vehicle is moving at, this passes through the radiator and around the engine, thus removing heat. When a vehicle suddenly stops, E.G. on a motorway when it has been travelling at 70MPH, that heat still remains, but its cooling air stops, heat from the engine rises, but also exhaust or cat heat is not being blown away. This rises as heat does, and gets round the highest point, usually the top of the engine, as the cooling water is pumped around more slowly due to the engine ticking over, this engine heat, additional heat, and slower moving water conspire to cause a lag between the thermo switch operating. This causes the engine temperature to momentarily rise, then as the fan activates, it pulls air through, and cools the water in the radiator; this then passes through the engine and begins to cool it down, usually slowly.
My suggestions are, based upon much experience of this condition; fit an electric fan in the engine bay, this must have a seperate fan switch, or a switch tapped onto the engine temperature sensor mounting in the cylinder head. The rating of this switch needs to be 5-10degrees lower than the radiator fan switch, this will cut in before the main fan and dissipate a lot of the hot air accumulating around the top of engine, and still work in conjunction with the main cooling fan.
One additional tip is simple, before shutting off the engine when you stop, or if you encounter traffic jams on the motorway; switch the vehicle heater to hot, put the fan on full crack, and open the windows, the internal radiator will remove a considerable amount of engine coolant heat.
Electric Water Pumps
Good advice from assassin. Some modern cars now feature electric water pumps. These are controlled by the ECU (computer) that runs the fuel injection and electronic ignition system. The benefits are : less drag on the engine caused by the mechanical water pump = more m.p.g, and more precise control of the engine cooling, by varying the volume of coolant circulating around the engine and also the speed at which it is circulated. These are normally used in conjunction with electronically controlled thermostats. Remember when cars had fan blades attached to the water pump or crankshaft
When you came out on a cold winter's morning and started the engine, these fan blades were cooling an already cold radiator - why 
That's one reason that electric cooling fans were introduced. The best way to prevent overheating, is to ensure that your cooling system is it tip top condition. Ensure that the fins in the radiator are clear, so that air can be drawn through it to cool it down.
Back in the days when
Back in the days when rear-engined double-deck buses were just becoming popular, many of the early examples suffered from chronic overheating problems due to the engine being encapsulated in a small area which also included an completely inefficient side-mounted rad and more often than not, was heavily lagged with sound insulation. Some models such as the Bristol VR's had front mounted rads, but by the time the cool water had arrived all the way back to the low revving Gardner6L3/Leyland.680 engine in summer city stop-starts, it was nearly as warm as when it left.
Thermostats were ripped out initially in panic measures but they had to be refitted come the winter. But the first solution for many manufacturers was to provide a fan, belt-driven off the engine which directed a stream of cool air from a dedicated inlet and directed across the cylinder head which had fair success - many of you may remember that warm gust of air when walking past the rear of an idling bus, especially welcome on a winter's day! Later this was combined with electric water pumps, the speed being controlled by a temp. sender which remains the norm today.
Dave with a Sporty
Dave with a Sporty
Poor Design
Remember these buses well, good old tubs which gave good service for many years, and the Gardener engined ones just went on and on like the Duracell bunny.
Do you remember the Triumph Stag, this too had severe overheating problems, this was one i solved; the problem was the coolant went the wrong way around the engine. Designing a new water pump, this incorporated an internal gear to reverse the impeller, many were made and totally cured the overheating of these cars.
I do well remember the
I do well remember the Triumph Stag - basically 2 Dolomite 1850 engines bolted together on a common crank - as my brother had on with the overheating problems which almost drove him to the brink of his sanity. It also spewed coolant constantly from the manifold/block matings (the manifolds were water cooled) no matter how much he tried to cure it.
Another overheating gem from way back when was the Hillman Imp, but was that not something to do with an iron head/alloy block?
Dave with a Sporty
Dave with a Sporty
Hillman Imps
The Hillman Imp engine was an all aluminium engine, and was originally made to power a portable water pump for the fire brigade. The cylinder block, and cylinder head used to distort, causing gasket failure. There was quite a good modification for this engine,which cured this problem. It involved machining circular grooves around each combustion chamber in the cylinder head, and fitting something called a Wills Ring. This was like a piston ring, but circlar in section. When used in conjunction with the head gasket, each cylinder was individually sealed.
Slight Correction
Not quite right with the application, but right with the principle.
Electric water pumps were first introduced by Citroen in the early 1960's before fuel injection became the norm, so this contradicts this slightly, although cutting edge at the time, it is improving technology which makes them viable.
Cost is the biggest factor, car electronics and DC motors are now so reliable, and available so cheaply that they are cheaper than conventional systems currently in use.
ECU controlled electric pumps are used not to reduce engine wear, but to help control the power management on modern engines. Anything which draws power in quantity such as electric fans, air conditioning pumps, and electrical water pumps demand a sudden amount of power, this sudden demand places a huge load on the alternator, this causes the engine to suddenly lower its revs at tickover as this load is placed upon it. To compensate for this, the ECU effectively blips the throttle as the load is placed upon the system, then levels the tickover out, it is not noticeable to the driver, but ensures the engines power output matches the required power to drive all the loads placed upon it. All this ensures that the engine works more efficiently, and the engine only supplies power when it is needed, this reduces the emissions output from the engine.