TD5 defender overheating

king karl · Apr 28, 2009

CharlesY said:
The radiator is a "WATER TO AIR" heat exchanger. It is not really a "radiator" at all - it is a heat exchanger at best, and a convector if you must.

Water can contain more HEAT per unit mass than almost any other substance, perhaps four thousand times as much as air.

So, we need several THOUSAND times as much air as water to carry away the heat from the engine coolant- and that means a lot of air has to pass straight through the fins of the radiator, air-to-metal, and not air-to-MUD!

I just went out this very minute and air-jetted the radiator fins of my 2004 Disco TD5. Quite a bit of crap came out, so it was worth doing.

Off-Roaders should be very careful to clean their rads after every trip.

30 seconds if coolant failure could cost any of us a whole engine.
OUCH!

CharlesY

Your not wrong, i feel i had a very close shave... lesson learnt

CharlesY · Apr 28, 2009

king karl said:
Your not wrong, i feel i had a very close shave... lesson learnt

As a matter of interest, the heat equation is worth keeping in mind.

In rough numbers, the heat energy from the fuel used goes three ways, about equally;

One third drives the car.

One third goes down the exhaust pipe as hot gas.

One third heats the engine, some radiated off the blocks and heat, but most taken away by the coolant, which means the radiator water.

If your engine is working modestly, say making about 40 - 50 bhp of WORK, that means the energy INPUT needs to be about three times that much. In kilowatt terms approx 50 bhp is about 40 kW.

So the radiator needs to dispose of about that much heat 40 kw or so and that is a LOT of heat.

It's no wonder they can boil up so fast, and fry themselves.

CharlesY

TD5 defender overheating

king karl

New Member

CharlesY

Well-Known Member

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