Help! Clattering sound at idle...

grenachenoir

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My C280 (V6) is having a bad month! Just fixed my aircon blower and now I am getting a metallic clattering sound from the engine at idle.

It goes away as soon as any revs applied and then the engine seems smooth and quiet as ever. I have tried to hear where it is coming from but it could be anywhere - although seems to be at the top end perhaps? It seems to have got louder in last few days but I could be being paranoid. Sounds horribly expensive though I hope someone has an easy (i.e. cheap!) explanation!!

Could it be timing chain tensioner? Don't know why this occurs to me but it's just a thought...does it even have a timing chain tensioner or am I making it up?

Desperate for someone who knows more than me to give me a steer in the right direction.

Thanks
Adam
 

Dave Bailey

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Essex
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C280 Elegance
C280 V6 Expensive sounding noises

grenachenoir said:
My C280 (V6) is having a bad month! Just fixed my aircon blower and now I am getting a metallic clattering sound from the engine at idle.

It goes away as soon as any revs applied and then the engine seems smooth and quiet as ever. I have tried to hear where it is coming from but it could be anywhere - although seems to be at the top end perhaps? It seems to have got louder in last few days but I could be being paranoid. Sounds horribly expensive though I hope someone has an easy (i.e. cheap!) explanation!!

Could it be timing chain tensioner? Don't know why this occurs to me but it's just a thought...does it even have a timing chain tensioner or am I making it up?

Desperate for someone who knows more than me to give me a steer in the right direction.

Thanks
Adam

Can anybody help with this one? My 280 has started doing the same thing, I saw this old post that goes back to 2003 whilst trying to search the forum for an answer.......

On my car I get a clattery tapping noise on tick over when the engine is fully hot. The noise sounds like it is ticking at half engine speed and is quite distinct. It is very difficult to hear exactly where it is coming from, but the source of the noise seems to be low down on the right side of the engine when viewed from the front of the car. Indeed, it is now audible from inside the cabin and is louder in the passenger side. When I first noticed the noise, it came and went in an almost rythmic way, the noise would gradually appear then subside again in a fairly regular pattern. It is now there all the time & I'm getting very worried. Could this be a timing chain/tensioner/stuck hydraulic tappet issue, or is there a pump of some sort or other type of gizmo that could be the problem? The car has now done just under 100k & has FSH, so I'd be pretty disappointed if this turns out to be a major problem. Though, with the way my luck has run to date with this car, I'm not optimistic....

Thanks in anticipation,

Dave
 

Dieselman

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Probably sticking hydraulic tappet, especially as you say it's at half engine speed.
 

se97mlm

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'98(R) Silver C240 Elegance
GrenacheNoir:

This happened exactly to me. It was the polybelt tensioner.

You can see it waggling when it's making the noise.

Quite an expensive part unfotunately. It cost me £118+VAT.

This problem also caused the rubber on the crankshaft pulley to wear out too, which was £150. Ouch!!

Dave
I think this ticking is normal: it's the little purge valve that feed the petrol vapours from the charcoal cannister into the inlet. This will tick for 5 or 10 minutes at idle then stop, then maybe start again after 5 mins or so.

It is the small valve on the RHS of the engine on the chassis runner, some distance forward of the washer bottle. See if the ticking is coming from there.
.
 
Last edited:

Dave Bailey

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C280 Elegance
Dieselman said:
Probably sticking hydraulic tappet, especially as you say it's at half engine speed.
I checked it out again, but the noise is definitely not coming from the top end. Thanks for the pointer though, much appreciated.

Cheers,

Dave
 

Dave Bailey

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se97mlm said:
[
Dave
I think this ticking is normal: it's the little purge valve that feed the petrol vapours from the charcoal cannister into the inlet. This will tick for 5 or 10 minutes at idle then stop, then maybe start again after 5 mins or so.

It is the small valve on the RHS of the engine on the chassis runner, some distance forward of the washer bottle. See if the ticking is coming from there.
.
Well, se97mlm, you were spot on! I located the valve and waited until the noise started. Lightly gripping the body of the valve, it is possible to feel it working. Thanks for your help, I can stop worrying about the noise now.

Cheers,

Dave
 

Birdman

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Dave Bailey said:
Well, se97mlm, you were spot on! I located the valve and waited until the noise started. Lightly gripping the body of the valve, it is possible to feel it working. Thanks for your help, I can stop worrying about the noise now. Dave
Had the same worry the other day - spoke to the garage and they confirmed it was the purge valve and the noise to be normal.
Odd how you can have a car for years and never notice its quirks and when you do, it can become really annoying. Bit like the wife. (Except with the car, finding it's normal comes as a relief!)
- Birdman
 

Dave Bailey

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Birdman said:
Had the same worry the other day - spoke to the garage and they confirmed it was the purge valve and the noise to be normal.
Odd how you can have a car for years and never notice its quirks and when you do, it can become really annoying. Bit like the wife. (Except with the car, finding it's normal comes as a relief!)
- Birdman
Funny you should say that..... This all started with the Wife, for it was she who asked the "where's that tapping noise?" question to begin with. I'd probably not noticed it before because I normally have the radio on. But because the radio was switched off so that we could "talk", it must have been quiet enough in the cabin to make the noise audible. And as we all know, once you've heard an odd sounding noise.......

Happy days,

Dave
 

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