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Mercedes-Benz engine repair questions and answers

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  • AutoMD Member
    AutoMD Member - 2000 Mercedes Benz E320 - Engine - 3/28/2014
    Does the engine temperature sensor control the electric cooling fan on this 3.2 liter gas engine?
    The electric cooling fan continually runs as soon as the car is started
     
    • Jimm
      3/28/2014 Jimm
      Yes, the coolant temperature sensor regulates the cooling fan engagement - it signals the cooling fan relay when an overtemperature condition exists - to start either one or both fans depending on; ambient air flow and temperature, plus the engine temperature as monitored by the coolant sensor.

      If the coolang fans run continuously, suspect these issues; defective / faulty cooling fan relay, faulty coolant temperature sensor, faulty wiring / connection at the radiator cooling fans. As a first step, and to narrow the source of the problem - use a length of jumper wire - from the battery 12VDC positive terminal to the coolaing fan motor connection - with the wiring connection unplugged. This isolates the fan switch, the fan relay and the temperature sensor.

      If the fans operate, then suspect the relay or the temperature sensor. The next step is to swap (exchange) the fan relay on the fuse / relay panel with another similar size and type relay - to see if the problem moves. If yes, then replace the cooling fan relay. If no, then replace the coolant temperature sensor.

      The parts are readily available from these many on-line sources, www.partsgeek.com, www.rockauto.com, www.discountautoparts.com, www.autopartswarehouse.com, www.jcwhitney.com - to list only a few possibilities.
      In fact, they (RockAuto) list the coolant temperature sensor from around $7.80 for your vehicle. Reference the website; www.AutoMD.com and the 'How-To-Guides' feature for the specific steps to replace the temperature sensor or relays.
      Jimm
      3/28/2014 AutoMD Member
      Thanks for the response, I'm with the idea of process of elimination, going with building the way up
      in regards to cost. Cheapest first, thanks again.
    • HouseCallAuto
      3/28/2014 HouseCallAuto
      Diagnosing the cause of the fans running continuously will require a professional that has a full function Mercedes Benz Star Tester that can communicate with the Powertrain Control Module (PCM), Signal/Activation Module (SAM), Automatic Air Conditioning (AAC), and Instrument Cluster Module (ICM). If there are ANY fault codes stored in these modules - even codes that do not directly relate to the fans, the fans will run continuous by default. This is not a DIY diagnostic. Anyone can buy a MB Star Tester for around $500 on one of the various websites such as aliexpress.com (no affiliation) as they sell copies of the genuine MB Star tester. The genuine MB tool cost more than 5 grand.
      HouseCallAuto
      3/28/2014 AutoMD Member
      First, thank you for your response. One of the reasons I try DIY is that I'm a practical owner with limited funds. I got more time than money and no payments. I try to keep the ol' wagon going. I am
      willing to go to the local chain that can read those codes and want me to buy the needed parts for the repair. I can live with the $7.80 to start. I appreciate the advice though. Thanks again
    • HouseCallAuto
      3/28/2014 HouseCallAuto
      The local chain will not be able to read any codes except the PCM codes. They don't have a Mercedes Benz Star tester
  • AutoMD Member
    AutoMD Member - 1999 Mercedes Benz SLK230 - Engine - 3/28/2014
    Why do the RPM's not increase when I step on the gas pedal?
    My car is stored and on a trickle-battery. The car does start but when I step on the gas, the RPM's do not increase. The engine just keeps humming and does this not very smoothly. Is perhaps the starter engine defect? Can it be the battery? Thanks
     
    • Jimm
      3/28/2014 Jimm
      Need more information - the engine does start? Yet after starting the engine does not increase in speed RPMs? Is this correct?

      What is meant by...'the engine keeps humming and does this not smoothly'? Is this in reference to the engine operation at low or idle sppeds?

      Please post a reply with more detail about the issue or condition for further assistance. You may also reference the 'Diagnose' feature on the AutoMD website for further details and as a guide to describe the issue.
  • AutoMD Member
    AutoMD Member - 2005 Mercedes Benz C230 - Engine - 3/25/2014
    Why am I getting "ESP Not Available" Message?
    Seems to be an electrical problem since my radio, lights and dashboard have fluctuations of power and it does not allow my gear to auto shift momentarily. Almost always have to shut it down and restart.
     
    0 answer
  • joe
    joe - 2003 Mercedes Benz SL500 - Engine - 3/25/2014
    How to open fuse box on a 2003 sl500 left hand drive the one in front of the battery
    Fuse for the secondary air pump has blown
     
    0 answer
  • AutoMD Member
    AutoMD Member - 2009 Mercedes Benz ML320 - Engine - 3/25/2014
    Is the adblue tank part of the emission control?
    my mercedes ML320 bluetec diesel check engine light came on. A local dealer told me that the adblue heater tank needs to be replaced. car has 34k miles. shouldn't that be covered under a govt warrantee or mercedes warrantee? The dealer wants 3300.00 to fix the problem.
     
    • HouseCallAuto
      3/25/2014 HouseCallAuto
      I would be screaming to the highest corporate level. You buy a diesel powered car to get better fuel economy and then you get slammed with this crap engineering. I would put up a fight big time.
  • AutoMD Member
    AutoMD Member - 1998 Mercedes Benz ML320 - Engine - 3/23/2014
    It won't stay cranked
    and the electrical locks don't work with the key or the button on the inside
     
    • Jimm
      3/23/2014 Jimm
      Need more information - not sure exactly what is meant by...it won't stay cranked...'? Does this mean that during the key start cycle, the starter simply drops out or shuts off? Does this mean the engine rotates with the starter but does not start?

      Please post a reply and clarify what exactly is meant - for further assistance.
      Jimm
      3/24/2014 AutoMD Member
      It Start's and gos right back died
  • AutoMD Member
    AutoMD Member - 1998 Mercedes Benz E430 - Engine - 3/23/2014
    It won't say cranked
    and the electrical locks don't work with the key are the button on the in side
     
    • Jimm
      3/23/2014 Jimm
      Need more information - not sure exactly what is meant by...it won't stay cranked...'? Does this mean that during the key start cycle, the starter simply drops out or shuts off? Does this mean the engine rotates with the starter but does not start?

      Please post a reply and clarify what exactly is meant - for further assistance.
      Jimm
      3/24/2014 AutoMD Member
      It cranks and gos right back died
  • AutoMD Member
    AutoMD Member - 2000 Mercedes Benz E320 - Engine - 2/27/2014
    Why is this water pump so expensive?
    is the part no longer made for the 3.2 V6?
     
    • HouseCallAuto
      2/26/2014 HouseCallAuto
      I would buy this pump online for under $75 with shipping included. Where are you shopping? No need to pay $500 for it at mercedes benz.
    • Jimm
      2/27/2014 Jimm
      The parts are readily available from these many on-line sources, www.partsgeek.com, www.rockauto.com, www.discountautoparts.com, www.autopartswarehouse.com, www.jcwhitney.com - to list only a few possibilities.
      In fact, they (RockAuto) list the water pump with gasket from around $50.80 for your vehicle.

      If you need directions / instructions for the replacement, use these websites; www.autozone.com, or www.AutoMD.com and the 'How-To-Guides' feature.
      Jimm
      3/4/2014 AutoMD Member
      I do appreciate your insight and I'm glad to be a member of this site. I have to start thinking about my will and what to leave AutoMD before my wife finds out!
  • AutoMD Member
    AutoMD Member - 2008 Mercedes Benz R350 - Engine - 2/21/2014
    Why will car not crank?
    Car will not crank over, battery charged, lights and accessories work but car will not crank over (no starter), engine runs fine when ignition system is bypassed (ignition on, starter manually engaged).
     
    0 answer
  • AutoMD Member
    AutoMD Member - 2008 Mercedes Benz R350 - Engine - 2/21/2014
    Why will car not crank?
    Car will not crank over, lights and accessories work, ignition bypassed and engine is operational but will not start in normal configuration.
     
    0 answer
  • AutoMD Member
    AutoMD Member - 1991 Mercedes Benz 420SEL - Engine - 2/8/2014
    Not starting?, turning over but not enough to start. 2nd try even less, 3rd try nothing.
    Put new battery in and still had to jump it. Had alternator checked and it is good. Will start after taking a drive down freeway but not after it sits overnight?
     
    • HouseCallAuto
      2/8/2014 HouseCallAuto
      The starter may be drawing too much current. Are you saying that it starts up immediately after attaching jumper cables? Maybe the battery is a defect?
      HouseCallAuto
      2/9/2014 AutoMD Member
      The new battery we put in is the same amps and terminals but smaller in physical size(measurement) would be the problem?
      HouseCallAuto
      2/9/2014 HouseCallAuto
      You did not answer my question. The new battery appearance should not affect the starting.
      HouseCallAuto
      2/9/2014 AutoMD Member
      Wanted to let you know that it turned out to be a defective battery so good job with your answer. We also had spark plugs and wires changed due to them being fouled. Starting great now and sounds a whole lot better.
      HouseCallAuto
      2/9/2014 HouseCallAuto
      Defective battery is rare but has to be considered. It always turns out to be something else more than 90% of the time. I guess this is in the 10%. Stay well.
  • davidriewer
    davidriewer - 1988 Mercedes Benz 260E - Engine - 2/2/2014
    Wont start unless i pour gas down intake.
    unless i pour gas down intake, the car wont start. has plenty of pressure to throttle body but none at injectors.
     
    • HouseCallAuto
      2/2/2014 HouseCallAuto
      Remove the air cleaner, disconnect the connector at the Idle Air Control valve (IAC) and test using a digital multimeter for presence of battery voltage (B+) at the Red/Blue wire at the IAC. Switch the ignition on. Also check the reading with the key on engine cranking. If the reading is less than B+ by more than 0.4v, replace the overvoltage protection relay.
  • AutoMD Member
    AutoMD Member - 2000 Mercedes Benz ML320 - Engine - 1/29/2014
    Oil filter assembly threads damaged
    where the oil filter cap screws in to the engine, is that called the "oil cooler"? and can it be removed? threads damaged!!!
     
    • Jimm
      1/29/2014 Jimm
      Need more information - are you referring to the oil filler cap on the valve cover - on top of the engine? Or are you referring to the oil filter housing for the oil filter element that is replaced when changing the engine oil?
  • AutoMD Member
    AutoMD Member - 1989 Mercedes Benz 300E - Engine - 1/21/2014
    Transmission oil is getting into the radiator coolant
    have replaced the radiator as advised to is there another reason this is occuring
     
    • HouseCallAuto
      1/21/2014 HouseCallAuto
      I can't think of another way tranny oil would get into coolant except for the internal radiator cooler. I assume you are asking this question because the problem did not seem to resolve after replacing the radiator? Is it possible that it is engine oil and not tranny oil?
  • dennis
    dennis - 2002 Mercedes Benz CL500 - Engine - 1/17/2014
    How to replace a vehicle speed sensor
     
    • wbrockstar
      1/17/2014 wbrockstar
      Its usually mounted on the side of the transmission.It takes the place of or does the same job that a speedometer cable does.Its electrical though instead of being a cable that plugs into the transmission,,like a mechanical speedometer cable does