Still driving around with the original expansion tank cap?

Recall campaign no. 98V-178 calls for a replacement cap, since the original doesn't release pressure when called for. The result is, instead of the cap letting out steam from an overheating engine, the pressure stays inside and bursts the weakest part of the cooling system, which unfortunately is the radiator inside the car. Expect the mechanic to charge around $1.000 plus parts for a new radiator, or do the replacement yourself (like I did). Some people actually consider it wise to let BMW replace the cap (no charge) BEFORE the damage is done. Go figure...!

Original cap part no.: 1 712 836
Replacement cap no.: 1 742 231 or 1 742 232 for the smaller/older engines like the M20.

Replacement cap on the left. The original has a 'top hat'. The replacement cap is completely flat but has a warning written on it. Lousy pictures, but I am afraid I don't have the old cap no more...