BMW 3-Series radiator replacement

Leaking E46 rad? You’re not alone. It’s a very fiddly and time-consuming task, as Andrew Everett demonstrates.

While the 1991-1998 E36 3-Series was blessed with a very simple cooling system and a radiator that could be replaced in as little as half-an-hour, the replacement E46 model is a lot more involved. For a start, the radiator is part of a ‘rad pack’ where the radiator and air-conditioning condenser are built and fitted as a complete unit at the factory. In addition, the previous integral header tank (expansion bottle) is now a separate unit clipped to the side of the radiator pack, and the hoses that were secured with worm-drive clips are now the pushfit clip-on type – these are intended to be quicker to assemble at the factory, but after a couple of decades they can be a real pig to get off again.

Our car here is a 2003 318Ti, with the four-cylinder N42 engine and manual gearbox. Autobox versions of the six-cylinder cars have a standard viscous mechanical fan (no electric fan to remove – just a plastic fan cowling), while automatics also have cooler pipes going into the base of the radiator that we obviously can’t show here. New rads come with a pair of plastic plugs that fit into the base of the radiator and there are two lengths, one for automatics and one for manuals. The main thing is to take your time, make notes and take photos, because this is not an easy or straightforward job.

On the subject of push-fit hoses, some cars have an extra plastic ring inside the end – if you find the hoses won’t clip on, remove the ring and try again.