Tapping / ticking and rattle on start-up

[c63jke]

Hello, I am aware there are some other threads for this, but none seem to come to a collective opinion.

I have a 2013 Edition 125 C63, it has 69,000 miles and full service history. I bought it just over 3 months ago, and since then, on 3 occasions it has made a loud tapping / ticking sound on cold start (see below linked video), but only until it is up to operating temperature (where the noise goes away). The tapping does indeed follow the engine RPM, but like I said, has only happened on 3 cold starts out of over 100, as I daily drive the car. I have heard that the hydraulic tappets / lifters on these engines are a common fault, so this seems most likely, but I have seen many others mention camshaft adjusters as an option as well. My main concerns with this are, will it damage the engine internals if i leave it until the problem gets worse, and is easier to take for diagnosis at a garage? Has anyone changed the lifters themselves, is it possible? I have already added hydraulic lifter additive and changed the oil to 5w. Mercedes quoted me £3000 to replace all 32.

Tapping

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Second issue is a rattle on start-up, this happens much more often, around 6/10 start-ups (hot or cold). It sounds like a chain rattle maybe (see below linked video, you may need to listen carefully), for a split second on start, but you never hear anything after that. I have seen similar threads opened and a whole range of suggestions thrown around, from the chain tensioner, camshaft tensioner, camshaft adjusters to even the air con compressor (and mine is actually broken, awaiting replacement at the moment). None of those threads seem to include any videos or sound clips of the rattle itself, hence why I thought starting a new one and including that could be useful. I have similar concerns regarding this issue (potential damage, ease of DIY).

Rattle

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If anyone has experienced any of this or knows anything that might be useful I would love to hear about it. I appreciate your time.

 

[TC350]

A different engine so may have nothing to do with it, but. For a couple of years or more I had concerns about tapping/ticking/rattling from my C350. I simple couldn't track down the location of the source - and neither could my Mercedes dealership when they had a listen. A long time later, MB spotted a tiny crack in the exhaust during a service. I got the crack welded up (not by MB, they don't do such things) and guess what? The cold start tapping/ticking/rattling stopped! I suspect that the crack opened up more when cold, causing metal to metal knocking under vibration. May be worth checking before pulling the engine apart.

 

[c63jke]

A different engine so may have nothing to do with it, but. For a couple of years or more I had concerns about tapping/ticking/rattling from my C350. I simple couldn't track down the location of the source - and neither could my Mercedes dealership when they had a listen. A long time later, MB spotted a tiny crack in the exhaust during a service. I got the crack welded up (not by MB, they don't do such things) and guess what? The cold start tapping/ticking/rattling stopped! I suspect that the crack opened up more when cold, causing metal to metal knocking under vibration. May be worth checking before pulling the engine apart.

Wow that's interesting, that would be a great outcome as well. Next time it happens I'll try stick my head under the car and see if I can hear anything. Did your tick sound like mine, and where abouts on the exhaust was your crack?

Thanks for the reply

 

[pcthrillrider2]

1st video sounds camshaft related

 

[c63jke]

1st video sounds camshaft related

What would need to be done to rectify that?

 

[jasonh]

The tapping/ticking - I'm not so sure that is a lifter. If one drains down it normally takes quite a time to fill back up, like 10 mins of driving.

The rattle sounds like the cam adjusters. The pin isn't holding them and it stops as soon as you have oil pressure (which depends on how long the car has been stood for). This is pretty normal on these engines and most people let it become a lot worse before getting it fixed. Doesn't seem to do any damage.

My C63 is actually quieter at start up with the 0W40. I drive the car infrequently and the oil often drains down, with 0W40 I think the car gets oil pressure faster on a cold start than with 5W40 (although logically that doesn't make sense because thicker oil should give a higher pressure). Perhaps something else is going on, but 0W40 sounds better at start up. 5W40 will give more protection if you cane it though!

 

[TC350]

Wow that's interesting, that would be a great outcome as well. Next time it happens I'll try stick my head under the car and see if I can hear anything. Did your tick sound like mine, and where abouts on the exhaust was your crack?

Thanks for the reply

I couldn’t detect the source of the noise by just sticking my head under the side of the car. It transmitted along the length of the exhaust up to the manifold. The crack was the engine side of one of the first silencers. I think I have a photo somewhere, I’ll try to find it.