How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Mike Your Own Question

Mike
Mike, Mercedes Technician
Category: Mercedes
Satisfied Customers: 39198
Experience:  Tech Expert
9261905
Type Your Mercedes Question Here...
Mike is online now

There I have a Mercedes C270, 2005 model. I am getting knocking

Resolved Question:

Hi there I have a Mercedes C270, 2005 model. I am getting knocking sound from the engine
area which we are unable to identify the source. I have had 3 different opinions from 3 different sources. One says it is the engine -valve or bearing. the noise has not affected the performance of the vehicle and since it stated I have done substantial mileage. If it was a bearing etc surely the engine would have seized by now. The second opinion is that the knocking is coming from the gearbox area. The third opinion is that it is the compressor. The car seems to run well for a period of time and then the engine light comes
on and it goes in to limp mode. We then reset the settings and it seems ok again. I know this may be difficult without listening to the noise but do you have any thoughts?
Submitted: 1 year ago.
Category: Mercedes
Expert:  Mike replied 1 year ago.
Hello and Welcome -
My name is ***** ***** Im happy to help.
As you say, it is difficult to some degree anyway without hearing it...even WITH hearing it sometimes as you have found but the idea is to determine what sort of noise it ie..ie, is it rotational..consistent with the speed of the engine..or a regular banging ..knocking and so on.
Sometimes you can narrow it down to the engine by putting the clutch in on a manual...or in N in an auto..to disengage the gearbox.. you see the point there.
Too - noises do "travel" but if you can get / use a mechanics stethoscope and try and pinpoint the area its coming from - or , use a long screwdriver in place of a stethoscope.. that will do the trick... Once narrowed down to an area of the engine, you can usually guess then where its coming from - ie..if its accentuated through the stethoscope on the very top of th eengine - usually its a cam shaft / or valve causing it- then you need to take the top off to check visually.
If its lower down the engine - ie, big ends etc.. thats usually a heavy knock rather than a tapping noise...
Too- if its a pulley causing the problem - or the compressor - the belts need to be removed to see then on start up / engine running (for a short test ) to see if the noise has now gone - if it has, its one of the components that is driven by the belts.. If it has gone, then a close inspection of each driven part will reveal the cause.
You dont say exactly which engine you have - the diesel engine tends to get failure of the main bottom pulley...so if thats the case, check that...
Working through as above you should get to the bottom of this..
Let me know how you go..and / or let me know if you need anything further on this..
~~~~ Meantime - Please do click on the "Exc / Ok rating" for me at this time.. "Thank you" in advance for that .
.. Note that you can get back to me anytime at all after doing the rating - it doesn't close you out.
-- Best Rgds, MIKE.
Mike, Mercedes Technician
Category: Mercedes
Satisfied Customers: 39198
Experience: Tech Expert
Mike and other Mercedes Specialists are ready to help you

What Customers are Saying:

 
 
 
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
< Previous | Next >
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex
 
 
 

Meet The Experts:

 
 
 
  • Matt

    Matt

    Mechanical Engineer

    Satisfied Customers:

    484
    BEng hons Mech engineering, in auto industry 22 years
< Previous | Next >
  • http://ww2.justanswer.com/uploads/35/350matt/2012-6-7_182356_matsavatr.64x64.jpg Matt's Avatar

    Matt

    Mechanical Engineer

    Satisfied Customers:

    484
    BEng hons Mech engineering, in auto industry 22 years
  • http://ww2.justanswer.com/uploads/EU/eurotec/2012-6-11_13153_mpjaphoto.64x64.JPG Marty's Avatar

    Marty

    ASE Certified Technician

    Satisfied Customers:

    21378
    Bosch Certified Master Technician with over 35 years experience in the automotive industry.
  • http://ww2.justanswer.com/uploads/MI/mikeamechanic/2013-4-2_175558_photo.64x64.JPG mike_a_mechanic's Avatar

    mike_a_mechanic

    Mercedes Mechanic

    Satisfied Customers:

    116
    17 years experience as a auto mechanic, foreign and domestic.5 years running my own repair business.
  • http://ww2.justanswer.com/uploads/MB/MBpaul/2013-8-21_204936_paul.64x64.jpg MB Paul's Avatar

    MB Paul

    Mercedes Technician

    Satisfied Customers:

    212
    Mercedes Benz Qualified Diagnostic Technician
  • http://ww2.justanswer.com/uploads/IN/indytech/2013-8-8_102717_SantoDomingo146598x6402.64x64.jpg Greg's Avatar

    Greg

    Technician

    Satisfied Customers:

    1081
    Automotive diagnostic tech
  • http://ww2.justanswer.com/uploads/TE/techmachine/0601821347169_717372168_8940977_39623330_o.64x64.jpg Ross's Avatar

    Ross

    Diagnostic and repair technician

    Satisfied Customers:

    453
    Licensed diagnostic and repair technician