I have been looking thru the threads, trying to find an answer to a tapping noise. You guys seem to now your stuff! My hubby is pretty sure it is not a valve. Engine makes a tapping sound, only in gear, hot or cold. I saw one poster had trouble with a Mott valve. I am going to tell him about that. Any other suggestions? I did take it to a German cars only mechanic, he's baffled. Not good. It is a '04 C320 Sedan.
That's what I am afraid of. Taking it to a German auto only shop, I thought would be the best. I guess I will have to go to the dreaded dealer. Thanks for the reply.
Like Kaninchen wrote, it should be checked by a mechanic, preferrably an engine rebuilder. Professional engine rebuilders should be able to pin-point the cause of the clicking/tapping/knocking. Noises such as these can have several causes, such as:
-connecting rod bearing wear/failiure
-wrist pin wear
-piston slap
-tired lifters/lash adjusters
-exhaust leaks
-broken valve springs
-weak or defective timing chain tensioners
-worn timing chain guides
-stretched timing chain
-evap. canister purge solenoid
Many of these noises come and go, can be dependant on engine temperature and/or being in gear or not, can be dependant on engine speed and so on. I would definitely bring it to a reputable engine rebuilder or the dealership. An engine builder has experience from a multitude of makes and models, while on the other hand, the dealer may have a TSB concerning your particular issue.
It only does it in gear, hot or cold. Sounds just like a valve tapping. I have a really good extended warranty, but my luck whatever it is, will probably be a "not covered part". Was hoping we could track it down before going to the dealer. Does anyone live in the Tampa Bay area? Know of the best dealer to go to? I have only had my beauty for a couple of months! I don't want to take it back!
It only does it in gear, hot or cold. Sounds just like a valve tapping. I have a really good extended warranty, but my luck whatever it is, will probably be a "not covered part". Was hoping we could track it down before going to the dealer. Does anyone live in the Tampa Bay area? Know of the best dealer to go to? I have only had my beauty for a couple of months! I don't want to take it back!
only in gear...on the throttle? if it is...it's the valves.
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2002 M112K with lots of mods
2008 M272 with some mods
I have been looking thru the threads, trying to find an answer to a tapping noise. You guys seem to now your stuff! My hubby is pretty sure it is not a valve. Engine makes a tapping sound, only in gear, hot or cold. I saw one poster had trouble with a Mott valve. I am going to tell him about that. Any other suggestions? I did take it to a German cars only mechanic, he's baffled. Not good. It is a '04 C320 Sedan.
I'm miffed that a German Mechanic cannot at least find the cause.
Sheesh how hard is it? He's right there under the hood.
Madam, might I recommend this ( I'd do this if I was in your shoes )
Do a Full Oil Change. New Oil, Filter, 3 O-rings and substitute 1 or 2 quarts
with Oil that has Anti-Valve, Tapping Noise
Go to Autozone or Discount Auto and ask them about it.
A simple can or two of anti-tapping fluid might resolve your problem.
It may not, but it's a cheap solution.
Again, that would be my second step.
My first step is to get a thorough VISUAL INSPECTION of the Engine and Tranny.
I was in your neck of the woods last week so I won't be there for a few more weeks. Sorry.
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Charles Orlando, Florida United States of America
New Benz owner needs help 
I have been looking thru the threads, trying to find an answer to a tapping noise. You guys seem to now your stuff! My hubby is pretty sure it is not a valve. Engine makes a tapping sound, only in gear, hot or cold. I saw one poster had trouble with a Mott valve. I am going to tell him about that. Any other suggestions? I did take it to a German cars only mechanic, he's baffled. Not good. 
It is a '04 C320 Sedan.
Linear Mode
