1988 240 radiator problem

Post by **john_boy1959** » 28 Nov 2009, 01:10

Hi there, when I'm driving the car's radiator seems to be working ok with the airconditioner on, however if I'm stationary in traffic the temp creeps up towards the red! Is this normal? The coolant is new and there are no obvious leaks from the water pump or radiator both of which are original. The car has done 245,000 kms. The temp today was 30C.

Post by **billofdurham** » 28 Nov 2009, 11:10

A slight increase in temperature whilst stationary is normal but getting near the red isn't.

Which radiator fan is fitted, electric or viscous coupling?

An electric fan should come on, and run continuously whilst the air conditioning is on. If an electric fan doesn't do this then there is a fault, usually in the fan relay.

A viscous coupled fan is driven by a belt from the crankshaft. If it is one of these check the tension of the belt and adjust if necessary. A viscous coupled fan is designed to rotate fairly slowly when the engine is cold, regardless of the engine revs. As the engine reaches normal temperature the viscous coupling tightens and makes the fan spin faster. When the temperature goes above normal the coupling locks the fan and makes it spin at engine speed thus cooling the engine faster. The viscous hub is filled with oil which may, as it gets older, start to leak. This affects the efficiency of the fan. This is a quick test of a viscous coupled fan - with the bonnet up, motor running at normal or slightly above normal temperature turn off the engine and watch the fan. It should stop with the engine. If it continues to spin it is faulty.

Bill.