There are several things to remember when removing and refitting a BMW radiator.
The first is the fragility of the unit. Most modern BMW radiators are made from an aluminium centre core capped on both ends with plastic tanks.
The BMW radiator plastic end tanks are also fairly fragile and great care should be taken to not knock the plastic locating pins.
NEVER remove a BMW radiator cap from a BMW car radiator expansion tank or BMW radiator whilst the engine coolant is still hot. Great pressure can build up in some BMW radiator systems and the fitter must be sure that the engine and it's cooling system have had sufficent time to cool.
If your BMW replacement radiator is of copper and brass construction be careful not over tighten any threaded fittings such as the hole for the BMW radiator fan switch. The fittings are only soft soldered into the BMW radiator tank and can easily be broken if over tightened.
If your BMW radiator has an inbuilt oil cooler with threaded fittings for the pipes ensure they are not cross threaded when attaching.
Always, always, always replace the anti freeze solution when refilling the BMW radiator. The antifreeze also acts as engine coolant as it has a higher boiling temperature than water. Aways use the manufacturers recommended soultion and observe the correct ratio of water to anti freeze.
When you are confident that the BMW radiator is fitted correctly and all pipes are sufficently tightened you will need to run the engine until it gets warm enough for the thermostat to open and circulate the water through the entire system. It is ESSENTIAL to remove any trapped are from the BMW radiator cooling system as air expands greatly and can blow a BMW radiator from the pressure build up.
It is advisable to set the heater temperature control to HOT as this will allow water to circulate through the unit. Do not switch the fan on as this will only slow the process of heating the system.
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