Tut Tut Tut noice coming from my C Class 320 petrol

[EBrant]

Hello

Recently I purchased a 2004 model (W203) C Class 320 petrol 4 door salon.

The car looks and drives like new and has covered 38k miles with a full mercedes main dealer service history (the MOTs were also all done at the mercedes main dealer) one owner car.

The only thing that I find odd (not had one of these cars before so perhaps it is common) is a tut tut tut noise (it is not that loud but noticeable), mainly noticed when waiting at the traffic lights for example, do not hear it when driving.

when sat in the car (I am in the UK) the noise appears to come from the front left side (e.g. near side, curb side, pavement) of the engine bay.

Therefore whilst the car was running I opened the bonnet (hood) and stood in front of the car looking into the engine bay. To my right hand side (as I am now facing the opposite way then when sitting in the car) I see a black plastic (possible metal painted black) block which all the brake fluid pipes go into (possible part of the ABS or Cruise Control) the tut tut tut noise now sound more like a tick tick tick noise (like a noisy mechanical clock) and it is coming from the general area of around this black block (block is about size of an A5 post card may be a bit bigger).

I would say there is about 3 tick tick tick noises per second as the car ideals (I think it sounds like tut tut tut when I am in the car due to the engine bay chamber making the sound larger)

Any ideas what this is please?

Thanks
EBrant

 

[LostKiwi]

Turn off the aircon and see if it goes away

 

[Uncle Benz]

Tank purge valve

 

[LostKiwi]

Tank purge valve

Yep I'd go with that too. In which case the ticking is normal unless you have codes to say otherwise.

 

[Arudge]

Below and to the left of the hydraulic block that you spoke of, is a valve a little larger than your thumb, with MOT written on the top. That's your purge valve.
Next time you hear it, put your finger on the top and you should feel the valve in operation.

 

[EBrant]

Thanks very much for the quick replies

The aircon was not on (as far as I am aware, I will double check)

may I ask what is a Tank Purge Valve please?

I thought the ticking might be normal as the car drives like a dream and goes like a rocket (well for me any way), and there is no faults indicated on the dash display. Although it does have a couple of stored fault codes (see attached diagnostic report from mercedes garage when I brought the car)

But because Mercedes Benz are supposed to be high quality cars I thought it odd to hear this tut tut tut sound (almost like you would get with a diesel car, but quieter) when sitting still, when you expect quality cars like this to be silent (my previous car was a BMW 3 series and I never hear noise from the engine bay when sitting at traffic lights)

Not sure if the attached might help too,

Thanks again
EBrant

 

[EBrant]

by the way the attached report mentions an issue with the heating system, although I should mention the heating appears to work fine (well for me any way)

Thanks

 

[Arudge]

The purge valve creates a partial vacuum in the fuel tank using the vacuum from the inlet manifold. Its an emission control thing to control the the escape of fuel vapour to atmosphere.

 

[Arudge]

I think that's the electric water pump that allows hot water to be pumped around the heater when the engines off. So you can sit in your car with the engine off but still have hot air to keep the cabin warm. I believe they quite often fail. You'll probably never use it either.

 

[Flyinspanner]

Could it be a slightly disparaging passenger?

 

[Arudge]

Could it be a slightly disparaging passenger?

That was dreadful.

 

[EBrant]

Thanks very much everyone for your advise, most welcome. I will follow Arudge advice about putting my thumb on the valve

"Below and to the left of the hydraulic block that you spoke of, is a valve a little larger than your thumb, with MOT written on the top. That's your purge valve. Next time you hear it, put your finger on the top and you should feel the valve in operation"

Cheers
EBrant

 

[John Laidlaw]

That was dreadful.

Could be the wife certainly!

 

[DREAMER NO2]

Would this model still have relays under the abs cover ? The could click, or tick tick ..

 

[EBrant]

Hello All

I checked the item Arudge suggested i.e.

"Below and to the left of the hydraulic block that you spoke of, is a valve a little larger than your thumb, with MOT written on the top. That's your purge valve. Next time you hear it, put your finger on the top and you should feel the valve in operation"

That part is indeed the item making the click click click noise and you can really feel it when you put your finder on it (I assume it is supposed to do that?). I guess I am just used to my BMW being a much quieter car so will just have to get used to it.

Thanks again for all you help

 

[Frosty149]

I’m no expert but, I don’t think it’s normally that intrusive!

 

[Arudge]

Hello All

I checked the item Arudge suggested i.e.

"Below and to the left of the hydraulic block that you spoke of, is a valve a little larger than your thumb, with MOT written on the top. That's your purge valve. Next time you hear it, put your finger on the top and you should feel the valve in operation"

That part is indeed the item making the click click click noise and you can really feel it when you put your finder on it (I assume it is supposed to do that?). I guess I am just used to my BMW being a much quieter car so will just have to get used to it.

Thanks again for all you help

Perfectly normal operation. The purge valve is a solenoid valve that opens and closes quite rapidly, I can only assume the on/off function is to control how much vacuum is released. But rest assured all is well.

 

[Arudge]

Just reflecting on the OP' s last post. The valve shouldn't be that audible, I can't hear mine.

Check that it hasn't slipped it's harness and it isn t sitting on the chassis rail, that would certainly make it louder.

 

[Uncle Benz]

In my experience some are louder than others. You could try a new one, or I have seen them wrapped in foam to hush them up a bit

 

[EBrant]

OK Thanks Arudge and Uncle Benz will do