Cracked Rad

Seth Brundle

Would a cracked rad cause a car to overheat?

Run_to_da_hills

Yes if all the water / steam evaporated out of it. Temperature would then shoot up, same as blown a head gasket or bypass hose. If you catch a cracked / leaking rad on time it will save warping your cylinder head. :eek:

Seth Brundle

Cheers. Water pump replaced as per Mr. AA's advice. Stat opened up, rad flushed and still problem exists. The crack was why I called the AA and the car (E39 523i) hit the red light but thankfully the head seems fine.
I'll be getting a replacement rad soon and will let you know if that solves it. (fingers crossed)

Mr.Diagnostic

Killian,

Your car, in common with all cars, coolant systems run under pressure. The pressure in the system raises the boiling point from 100c to 120c. With a crack the system can not build the pressure so will boil at the lower temp. Also the crack can cause the coolant level to drop and hence overheat. It is not unusual for your car to run at well over 100c under normal circumstances.
One thing that is often mentioned is that the gauge normally sits at half when the E39 is right. The fact is that the gauge reading bears no resemblance to the actual temp. It is designed to read at the mid way point as long as the temp stays under control so as not to worry the driver. Most drivers would crap themselves if they knew the actual temp of the engine while sitting in traffic on a hot day. If I am monitoring coolant temp I do so by reading live data from the engine management system and the use of an infrared tem gauge for local temps.

HTH

Seth Brundle

Cheers Alan