Hard plastic line that runs between the expansion tank and the upper radiator hose. The plastic connector at the radiator is a weak point and prone to leaking coolant.
This part is listed by BMW as BMW part number 17112229053 (17-11-2-229-053) and is described as the vent hose / water pipe / connecting hose from the radiator to the expansion tank on E46 M3.
This is a Genuine BMW vent hose with a two year warranty. Buying a Genuine part will usually be more expensive than an OEM or aftermarket brand but you are assured that it meets BMW's designs for fitment, performance, and longevity. It will also be the very latest design, incorporating any updates or revisions that an aftermarket brand typically will ignore.
For full BMW fitment information or for assistance from one of our BMW experts, we recommend calling us 877-639-9648.
BMW Fitments:
3 Series
E46 (99-05) > M3