CLK 320 Vibration

[MB Novice]

I have a CLK 320 C209 (2003). It had a noticable vibration felt through seats and steering wheel while idling.

I had the engine mounts replaced. This cured it by 50% but it is still present and the engine can be seen to be vibrating.

Mechanic now says that it is probably the spark plugs which he says should be replaced between 35000 and 60 000 miles - mine has 44000. Says the leads will probably have to be replaced at same time as they often break in the change over.

I am a little sceptical about the need for this as he tested the spark plugs before doing the engine mounts and said that they registered no problem.

Saw this problem referred to in a post back in 2006 but there was no outcome. One member had suggested it may be a "front crankshaft pulley breaking up and causing vibration".

Would welcome any advice on this issue.

 

[Xtractorfan]

Have you had it checked on a diagnostic machine

 

[brandwooddixon]

Did he use pattern parts or MB for the engine mounts?

I have heard bad reports about non-genuine MB engine mounts.

Is the vibration worse when in gear or in nuetral?

Does it increase in intensity when moving away or coasting?

If you gradually increase the engine revs whilst stationary and in neutral can you hear the engine missing at all? Is the nature of the vibration any different?

Have you had the spark plugs replaced at all in the past? Always worth a try anyway if they need doing, but use the proper platinum ones for the best results.

 

[BlackC55]

I would say it is probably the leads and /or plugs.

 

[Uncle Benz]

I would say it is probably the leads and /or plugs.

I concur. 2 plugs per cylinder mean misfires can be more subtle than you might expect. Find a decent indy with a star machine (oh, look above...) and get them to look at the engine smoothness check screen. Dodgy leads are easy to spot then...

 

[type49]

I concur. 2 plugs per cylinder mean misfires can be more subtle than you might expect. Find a decent indy with a star machine (oh, look above...) and get them to look at the engine smoothness check screen. Dodgy leads are easy to spot then...

Yep! I agree with leads. Replacing all 12 is quite expensive though. As above, find someone who can diagnose it properly. Where abouts are you?? Do a search on the recommended indie section.

 

[MB Novice]

Your replies

Thank yu all for your replies.
In answer to your questions;
Xtractorfan - the only diagnostic machine used was one to check the spark plugs. The result was, according to the mechanic, that there did not seem to be a problem but he still recommended new plugs and leads. This seems strange to me because if he is right then his diagnostic machine must be faulty, musn't it???


Brandwooddixon - the mounts were genuine MB.
The problem only exists when in neutral, there is no sign of misfiring and it is not noticeable when revs increase or when driving.

BlackC55, Unclebenz and Type 49 - I note your comments. My mechanic says leads must be replaced at time of plugs as they often break in the change over. Do you think this is right or is he just looking for more money. Neither have been done. I presume the plugs would be more important

 

[MB Novice]

STar machine???

Uncle Benz
what is the star machine you referred to?

 

[Uncle Benz]

Star machine is the term often used to describe the official mercedes diagnostic tool, called HHT for earlier models and DAS for newer stuff. Many independents now have these machines, and they are a very powerful tool - I am still finding new things mine can do!!

 

[type49]

Thank yu all for your replies.
BlackC55, Unclebenz and Type 49 - I note your comments. My mechanic says leads must be replaced at time of plugs as they often break in the change over. Do you think this is right or is he just looking for more money. Neither have been done. I presume the plugs would be more important

I wouldn't like to count how many plugs I have changed over the years - I guess I have broken some leads in doing so but I really can't remember when.

 

[jberks]

I've had more problems with the leads than the plugs, replacing 2 sets over 70k as against 1 set of plugs. First set at around 30k to fix an idle misfile. The plug change was in response to a slight miss at 65k and figuring they were overdue I changed them, but the missfire remained and I had to change the leads again. The short leads on these engines do seem to be a bit fragile.

 

[bazzle]

I have also found "soft" misses in neutral/park that are not their in drive...

BAzzle

 

[kth286]

MB Novice

Even though you have a premium brand car do not automatically expect you will get premium brand service.

The incompetence I have found within the Mercedes servicing population (from both main dealer and so called specialists) beggars belief at times.

It is partly our own fault as we consumers are not demanding and knowledgeable enough to demand that proper service.

Your own experience to date is proof enough - one miniute the plugs are OK then they are not OK - what's that about.

The techs are ofter under time pressure - no doubt.

BUT we are loath to pay for diagnostic time, and we should not be loath.

BUT we need to know that the guy dealing with the diagnostics is competent - which is very difficult indeed.

He/she may have the most sophisticaed equipment but still they must be able to use it correctly and also be able to translate what the equipment is telling them.

If the machine is telling them there is a fault in 'so and so' circuit, they still need to know what is causing that circuit failure and how to make a permanent repair - the machine cannot do that for them.

The SMMT and Gov are trying to introduce a competence system among vehicle techs and a very slow process it is - where they WILL need to have min recognised qualifications to be able to deal with certain vehicle repairs which represents their expertise.

We the public at present do not know what to ask of a tech to test whether we are getting value for money.

But you now need to do your research to find techs with good proven reputations in diagnostics (a rare breed) and not assume because the name Mercedes is above the door, they are automatically capable.

Refering back to your case, the tech needs to test you high tension system for breakdown using an oscilloscope which shows the actual trace shape of the firing spark, and it will highlight which if any are failing when compared to each other.

So you need to ask for that test to be done before any dismantling and demand a print out.

The reason the leads are broken is because access is difficult for some of the plugs/leads at the rear cylinders and also the techs often do not have access or use the correct tools to remove the leads successfully.

Best of luck and do report back your findings/results.