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How the Cooling System Works

By Mr Ed

The Cooling system is one part of an engine that everybody takes for granted, but it is one of the most likely areas that, if neglected, will cause the most frequent breakdowns and no end of problems. This article gives a summary of how the system works and how to keep it in good condition.

How it all works

Your engine is made of iron. Many problems are due to the fact that people forget that Iron rusts. Orange radiator water is usual but highly undesirable as it indicates your engine is rusting from the inside out.!!!
Cars work on the Scavenge System in that the water pump scavenges water from the bottom of the radiator, and pumps it around the engine and ancillaries, finally, dumping it back into the top of the radiator. From here it filters down through the radiator matrix, being cooled down, ready to make the journey once again.
The main things that interest us with regards to the cooling system are the Heater, the Radiator, the Thermostat and the Water Pump.

Cleaning the system out

Water Flow, for the heater, comes out of the head - through the heater valve - into the heater - back out of the heater - back to the engine bay.
A back flush is where you disconnect at the heater valve and at another point where the hose comes back out from the heater (in engine bay of course) and attach a hose pipe to this return pipe and flush fresh water the wrong way round the heater matrix.
Be careful though... Not too high a pressure as this could cause a failure of the heater matrix or flood the inside of the car if one of the hoses that connect to the heater inside the car comes off. Nice and gentle to start with and gradually increase the pressure.
Watch for nice clean running water coming back out of the in hose to know that you have done a good job.
Now reconnect the heater hose back to the heater valve, making sure the valve is now open, and remove the radiator cap and continue flushing for 10 or 15 minutes or until again, nice clear water comes out of the radiator.
Finally, drop off the bottom hose on the radiator, and allow the system to completely drain of all water.
Re-attach the bottom hose and re-fill the system with a 50/50 solution of antifreeze and water.
Good antifreeze will have a corrosion inhibitor in it and will also stop your radiator matrix and heater matrix from getting crudded up with corrosion particles again.
Antifreeze should be in your car all year round, not just Winter.
And finally, don?t scrimp on the antifreeze. Get a decent one, preferably Glycol Free.

Thermostats and water pumps

If your thermostat has failed, your radiator will get hot, but it will take longer than normal to.
You see, the thermostat also acts as a restrictor, to make sure coolant always gets to the back of the head (No 4 Cylinder and heater outlet!).
A lot of people think that because their car is overheating, they can remove the thermostat and it will reduce the overheating. But by doing this, sure, the area around the thermostat is always cooler (due to increased coolant flow) and your temp gauge is always reading cooler due to the location of the sender unit.
However, because of the lack of flow to the back of the head now, you get localised hot spots, hence making your supply hose to the heater matrix really quite warm, but because of the now seriously low pressure here, back pressure from the return hose prevents any water flow. In fact, if anything, you get a slight negative water flow, hence, the cold return hose.
The above is the main reason that if you do away with the thermostat on a performance engine, you need to blank off the Bypass hose between the head and the Water Pump, and put in a Thermostat Blanking Sleeve instead of the thermostat.
This will ensure that you have positive water pressure at the back part of the Cylinder head, and hence water flow through the heater matrix.
Never ever remove a thermostat for any length of time. Its one of the fastest ways to kill your engine by overheating. Things to do with respect to thermostats

  • Makes sure your thermostat is changed regularly (92 degree unit for Winter driving and an 88 degree for Summer driving) and hence always in good condition.
  • Makes sure that your car is going to be running at the best optimum temperature all year round.

Water Pumps

These do exactly what it says on the box.
You will see advertised ?High Flow Water Pumps?? Poppycock?..
These are no use whatsoever unless you have and upgraded radiator matrix and more efficient fan system.
A standard radiator can only cool so much water down, and if its being pumped through the system faster by an up-rated pump, then it wont get the chance to cool down to its true potential. Do not be fooled into the false understanding that by using an upgraded Pump on a standard system that you will get more efficient cooling. The reverse is probably more true.

So there we have it ladies and gents.

Hope this little post helps you understand your cooling/heating system better and helps you to keep your feet warm in the Winter, and your engine a little cooler in the Summer.

All the best,
Steve Ed


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