Ticking Noise

[Ledbelly]

There's a ticking noise under the bonnet on my '02 E240 W210. It's coming from a little electro-pneumatic or vacuum gizmo just by the ABS pump.
What is it and does the ticking matter?

 

[DSM10000]

There's a ticking noise under the bonnet on my '02 E240 W210. It's coming from a little electro-pneumatic or vacuum gizmo just by the ABS pump.
What is it and does the ticking matter?

Start to worry when the count down reaches 10, 9,8,7,........

 

[Jobsworth]

Tank purge valve by the sounds of it. Nothing to worry about if that's the case. Google a picture, see if it matches.

 

[Ledbelly]

Thanks Jobsworth. That's the very thing!