Cold start noise

[30something]

On my W124 280te, there is a pump of some sort which runs for a few minutes after a cold start, then clicks off, it's pretty noisy (well compared to the engine anyway) sorry if it's a dumb question , but what does it do? and could it need replacing?

 

[Dieselman]

It's the air pump.
This blows air down the exhaust so the over ich mixture doesn't poison the cat.
They vary in noise and sometimes it can come and go. You could try lubricating it, otherwise forget it as a new one will cost more than the car.

 

[30something]

Thanks, I will keep an eye (or an ear!) on the amount of noise it makes, is it an option to bypass it? every other cat equipped car I have owned has got by without such a device.

 

[Dieselman]

Just live with it. It only runs for about 30 secs.