paul-the-limey

Hi,

I have a 2001 C240 Automatic and I was looking under the hood today and found a component that was making a fairly loud ticking sound. Can anyone tell me what it is? Can anyone also tell me if its meant to make a ticking sound and if not then what this may indicate (apart from the fact that it's probably knackered!!)?

enc: 2 pics below

Thanks.

Paul

This is it:



and this is where it is in the engine bay:

mbtech208

That is the charcoal canister purge valve. When it ticks, it is working. Fuel vapors in the tank build up, are stored in the charcoal canister, and are released into the engine to be burned. The purge valve is what delivers the vapors into the engine from the canister. There is an updated mounting bracket for the purge valve that is supposed to make it quieter, but you will still hear it. It will always make noise, you'll probably have to learn to live with it.

truelove

at what frequency does it tick? i can hearing ticking under my hood too, but i assumed it was the spark plugs.

mbtech208

Put your hand on it, you'll feel it pulsate as it ticks.

tyro

paul-the-limey

Thanks MBTech208. I wasn't sure so thought it best to check. Never heard it until I opened the hood to poke around.

The noise is not too bad kind of like the level of volume a loud quartz clock makes but faster (say 4 ticks per second). I thought it might be a component on the way out which is why I wanted clarification.

In fact it is kind of like the sound a spark plug makes when shorted out against the engine body (tick,tick,tick,tick) so i can understand truelove's comments.


Thanks.

Paul

mbtech208

Some people have complained that they can hear it inside the car if the engine is idling and all the accessories are off. Sure enough, the noise can be heard. This is one time where the term "They all do that" is correct.

truelove

hey, i'm an electrical engineer not a mechanic. i just figured something that makes a spark would tick.

SUNILP

I hear i t tick as well. I thought it was a problem with my car only. I have a 2003. Would it have the updated mounting or shall I request it?

mbtech208

The updated bracket only applies to 2001 models. All newer ones have it already, but the ticking noise is still audible.