I'm not sure if this has been covered by anyone else before.....
Lately ive been noticing my car overheating on hot days. This happens while driving through the city (Sydney).
In normal traffic conditons the temp sits at 1/3 with no a/c, and 3/4 with the a/c on.
When traffic is heavy (stop starting) it sits on the red with a/c on. As soon as I turn off the a/c it goes straight back down to 1/3 - 1/2.
Do i have a blocked radiator?... should I replace the coolant ?
Take out the radiator out and blow the grass seeds, dust and bugs from your A/C condensor and the radiator. Then flush the system.
If that doesn't work try a cooler thermostat in the summer months.
Also if it is a aluminium radiator, it could have a build up of scum on the inside of the core that doesn't allow the transfer of heat. You can't Flush clean them because the costic based cleaner eats aluminium. If possible buy a brass cored radiator, did wonders for my EB.
My car does the same as yours, the cooling system gets flushed regularly and the thermostat was replaced 2 years ago.
On a hot day the temp gauge stays halfway but once the air con comes on the temp gauge goes to the red.
My theory is either the aircon compressor bearing is seizing up but then you would probably hear some sort of noise or and more likely the waterpump impellor has corroded and isn't circulating the water in the engine much.
Haven't done anything yet, waiting for the Christmas break.
Because of the design of the engine bay in the XDs onwards, they tend to run hot, due to lack of air circulation. Just have a look at the engine bay of an XA, B or C and see the difference.
Because of the emission laws, the engines are also designed to run hot, as that assists in the dissipation of the gasses etc. The temp. gauge is configured accordingly by adding resistors in the right spots.
It is essential that the cooling system is maintained, and this generally means an annual flushing, with radiator renewal every 5 years or so, as the tranny cooler also sits inside the rad. and tends to dissolve over the years.
The main reason that the car tends to overheat in hot weather is the above not being done, and also look between the aircon. heat exchanger (rad) and the radiator, as this can also be filled with gunk.
A lot of EAs onwards end up beside the road with the binnet up in hot weather simply because the cooling system has not been maintained.
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