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Mercedes-Benz engine repair questions and answers

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  • nilo
    nilo - 1980 Mercedes Benz 280SE - Engine - 7/29/2013
    What could be wrong with my 1979MB 280SE, Hard to start esp. for the first time, seem no have insufficient supply of gas
    I need to put little gas in the carb so it starts easier for the first time. But after travelling about 20km its hard to start again.
    0 answer
  • daystrom1
    daystrom1 - 2006 Mercedes Benz S430 - Engine - 7/28/2013
    The RPMs are revving too high when I drive the vehicle. The closer the speed gets to 50 mph the RPMs move between 5 and
    The closer the speed gets to 50 mph the RPMs move between 5 and 6 and the vehicle starts shaking.
    0 answer
  • fsampa2002
    fsampa2002 - 1997 Mercedes Benz E320 - Engine - 7/17/2013
    I kept on getting a service overdue message and exhaust temperature high,the car has just stopped .
    wenever i want to start the car,the engine cuts.wat cud be the problem?
    • wbrockstar
      7/17/2013 wbrockstar
      The exhaust temp bein high is suspect.Clogged converters can cause this and when they go bad the car wont start due to exhaust bein restricted.Do you know what service is actually overdue
    • fsampa2002
      7/17/2013 fsampa2002
  • braswellvp
    • HouseCallAuto
      6/22/2013 HouseCallAuto
      You or anyone else is not gonna figure this out without knowing what fault codes are stored in the ecu. You must check for codes, that means connecting an appropriate scan tool to the diagnostic connector and reading the fault codes. Skip that step and this is just a game of guesswork and throwing parts at it. You can do a visual check and make sure that there are no vacuum leaks caused by a cracked or disconnected hose but beyond that this is not gonna get figured out without data.
    • rickettsgeorge
      7/16/2013 rickettsgeorge
      car not starting but idies engine not turning on
  • grinor00005
    grinor00005 - 2000 Mercedes Benz S500 - Engine - 7/13/2013
    My car has been sitting up for about a year, the lights are flashing an it wont start
    it has 103,000 miles, I changed the battery, an it still wont start
    • Jimm
      7/13/2013 Jimm
      Need more information - what is meant by 'it won't start'? Does this mean the starter motor does turn when the ignition key is turned? Does this mean the stater motor does not turn when the key is turned? Does this mean the stater does work, yet the engine will not run?

      Please clarify what is meant and provide as much detail as possible for further assistance.
  • andrebritt
    andrebritt - 1993 Mercedes Benz 300E - Engine - 7/13/2013
    Sometimes my car will lose power and wont excelerate,but if I turn the car off,let it sit for a few mins,hrs it runs
    227k,all the plugs,belts have been changed.this problem may occur every other month depending how much I drive it.when it occurs and I take it to the mechanic nothings wrong cause the car starts running fine feel like the car is not getting enough gas or ...
    0 answer
  • Punch_Products
    Punch_Products - 1998 Mercedes Benz C230 - Engine - 7/12/2013
    Service engine light on
    mechanic check and said p170 code oxygen sensor bad not sure which one how many sensors are there
    • Jimm
      7/12/2013 Jimm
      There are two (2) oxygen sensors on the 2.3L engine and exhaust system - one upstream and one downstream of the catalytic converter. Usually, if one O2 sensor is faulty - go ahead and replace both at the same time due to age / mileage and wear considerations.

      Check the following auto parts sources for the replacement parts;,, - to list only a few possible sources. For example, they (RockAuto) list the O2 sensor (either up or downstream position) from around $21.00 each for your vehicle.
      These are very simple to replace - check the 'How-To-Guides' feature on the AutoMD website for more installation details.

      P0170 means Fuel Trim Malfunction (Bank 1). P0170 indicates a malfunction in the PCM control of the air-fuel ratio. Bank 1 is the side of an engine that has cylinder 1.

      Possible Causes:

      Dirty or defective MAF sensor
      Vacuum leak
      Defective fuel pressure regulator
      Defective O2 sensor
      Oil contamination in the cam/crank sensor wiring or MAF/O2 sensor connector

      Possible solutions:

      Clean or replace MAF sensor
      Replace fuel regulator
      Replace damaged or cracked vacuum hoses
      Clean cam/crank sensor wiring or MAF/O2 sensor connector
      Replace O2 sensor
  • psales11
    psales11 - 2000 Mercedes Benz S500 - Engine - 7/11/2013
    The car will not start when it is hot and it cut off while driving
    It happens when the care is hot and when the car rest for about 30 minutes it starts. The car engine cut off while driving.
    • CVO
      7/11/2013 CVO
      The check engine light doesn't have to be ON to store a fault code.

      Check the vehicle for fault codes to see if there are any sensors were involved to the malfunction of the engine.

      1.Local auto parts stores such as Autozone ( not in California) or Advance Auto parts will scan and retrieve any diagnostic trouble codes ( dtc ) stored in the powertrain control module for free of charge..

      2. has the code reader for 17.10 dollars+ shipping.

      3.Re-post the dtc's in here " answer question " for further assistance.
      Autel MaxiScan MS300 CAN Diagnostic Scan Tool for OBDII Vehicles

      Note: we need the dtc's to identify the sensor, there are a dozen different sensors to operate the car.

      Visit this site and see all the different sensors.

      Note: the symptom described, it fitted for the camshaft position sensor, check it.
  • carlito
    • Jimm
      6/29/2013 Jimm
      Ther is no float adjustment - as was previously found on engines with carburetors.

      Under your air cleaner mounted to the side of the fuel distributor is your EHA valve. I would like you to disconnect the plug on the valve when the engine is running poorly and see if the engine smooths out. The valve controls your fuel mixture. If the engine runs better with the EHA disconnected I'd suspect a problem in the engine management circuit. Do not disconnect the EHA when the car is cold or the cold running will suffer.
      A faulty oxygen sensor can cause the fuel mixture to go rich. Disconnecting the EHA will tell you if the computer is trying to richen the mixture. Try the many on-line auto parts sources, such as;,, - to list only three - for the oxygen sensors or any other replacement parts.
  • crawfordtosha
    crawfordtosha - 2005 Mercedes Benz C240 - Engine - 6/25/2013
    What cause a car to shut down at red light and start back up
    0 answer
  • lkibbon
    lkibbon - 1999 Mercedes Benz SL600 - Engine - 6/20/2013
    At what tepprature should the auxilary cooling fan come on?
    • Jimm
      6/18/2013 Jimm
      Usually the radiator cooling fans would engage when the cooling system temperature reaches a point at or above the thermostat temperature rating. So, if the thermostat is rated at 195F, the cooling fans would engage at this temperature - or just above this point - to prevent system overheating or boil over.
      6/19/2013 lkibbon
      Thanks. If the fans do not come on what should i check?
    • Jimm
      6/20/2013 Jimm
      The engine coolant temperature sensor is utilized for control of the cooling fan. If the radiator cooling fans do not operate, the issue may be related to; faulty cooling fan switch / temperature sensor, faulty cooling fan relay, faulty cooling fan fuse, faulty cooling fan wiring / connection, faulty cooling fan motor.

      As a first step, check the fuse, relay and wiring for connection and condition. Next, test the fan motor itself by running a jumper wire from the battery positive to the motor - if the motor / fan operates at this point, then you can suspect these items; temperature sensor, wiring, relay, or fuse.
  • dunkkorzan
    • HouseCallAuto
      6/19/2013 HouseCallAuto
      If there is no spark present at all on that cylinder then your cause is the ignition wire or distributor cap. You did not mention which is missing.. spark or fuel and you have to know this to proceed.
    • dunkkorzan
      6/19/2013 dunkkorzan
      Spark is there, but i suspect the fuel. At idle it fires occasionally and at cruise without a load i.e. gently easing off the accelerator it seems to smooth out, but withnaload it misses continuosly
    • HouseCallAuto
      6/20/2013 HouseCallAuto
      So just so we are on the same page, have you really sold yourself on #8 being the dead cylinder, because there is no misfire code as the OBDII systems have, so a misfire on a pre '96 vehicle has to be diagnosed the old fashioned way, like removing a plug wire one at a time and seeing the change in engine rpm and shake. When you are at the bad cylinder and you remove the plug wire there is little or no change in engine running. Did you do that and are you convinced that #8 is the only cylinder that clearly has a miss? All the others are good? You also have to check for a vacuum leak near that cylinder also.
      6/21/2013 dunkkorzan
      The head mechanic at Meyer Ford garage in concordia, MO checked it and replaced the injector and spark plug and the compression was 125 psi. He thought the problem was somewhere prior to those items he checked since there was spark and the injector was good. He didn't wan t to go beyond that without a shop manual, but suspected the fuel distributor. You mentioned a vacuum leak. How would that be checked? I really appreciate your help! Dunk Korzan
  • Tony Lisbey
    Tony Lisbey - 2002 Mercedes Benz C240 - Engine - 6/13/2013
    2002 C240 stalls and ESP light comes on. Restart car, and all seems OK. It seems to happen only when coming to a stop .
    Seems to happen easier when engine is first driven for the day and most of the time when slowing or turning.
    0 answer
  • mikeparandian
    mikeparandian - 2000 Mercedes Benz E430 - Engine - 6/13/2013
    Hello every one : power steeling and water pump, also A/c
    I got year 2000 Mercedes E430, run great but get over het and a/c not cooling the sometime so power steeling acting funny is water pump problem , or something earls, is that electronic water pump? please help me on this thanks
    • Jimm
      6/13/2013 Jimm
      Loss of coolant because of a coolant leak is probably the most common cause of engine overheating.
      Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.

      A good cooling system should hold 12 to 15 psi for 15 minutes or more with no loss in pressure. If it leaks pressure, there is an internal coolant leak (most likely a bad head gasket but possibly also a cracked cylinder or engine block).
      Not sure what is meant by...'the power steering acting funny'. The E430 4.3L engine uses a standard belt-driven water pump.
  • BillyK3
    BillyK3 - 1987 Mercedes Benz 190E - Engine - 6/12/2013
    How can I fix a high idle speed?
    My idle speed is too high. I think it is a sensor issue because when engine is cold this doesn't happen.
    • Jimm
      6/12/2013 Jimm
      Check all the engine vacuum and all air intake hoses as a first step - for leaks / cracks / damage. Replace as necessary. Next step - check the idle speed actuator / idle control valve on the throttle body. Normal Idle speed should be 800-850 RPM.

      Check the many on-line auto parts sources, such as; www.autopartswarehouse,, or for the replacement parts. For example, they (Rock Auto) list the idle air control (IAC) valve from around $241.00 for your vehicle. Standard Motor Products part # AC384.