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Mercedes-Benz engine repair questions and answers

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  • JIm Mathews
    JIm Mathews - 1988 Mercedes Benz 420SEL - Engine - 5/7/2014
    Purchased this car with retrofitted R134 AC. Brought to local Shop. They put 2 pounds 134 in and cannot get AC cold
    Car does not get even slightly Cold. I was told maybe mono valve, etc. Blower motor works fine. Just no Cold AC at all!! They want to put in a new compressor, drier, etc!!
     
    • GT500Knights
      5/7/2014 GT500Knights
      Did they also include the necessary oil into the system? Without the oil, the compressor will fail. There are many things that can go wrong with the ac system, and it is very prone to leaks. Even the smallest leaks can cause the refrigerant to leak from the system within a weeks time, preventing the system from turning on (safety feature for compressor if refrigerant level is too low)

      Also I just looked up your car on alldata, 2 lbs is too much refrigerant. It's actually supposed to be about 1 lb 12 oz.
  • AutoMD Member
    AutoMD Member - 1994 Mercedes Benz C280 - Engine - 4/21/2014
    Why does the heat come on when I turn on the ac. and some time s when there's nothing on..
    The heat comes on when I turn on the ac, and sometimes when nothing is turned on..
     
    0 answer
  • AutoMD Member
    AutoMD Member - 2000 Mercedes Benz E430 - Engine - 4/15/2014
    Car starts right up, drives very good, then after about 10-15 minutes of driving the car shuts down while driving
    it will not restart for about 30 minutes.
     
    • Pepe
      4/15/2014 Pepe
      Sounds like the crankshaft position sensor or engine coolant temperature sensor... Check the PCM for any codes, that should point you to the right direction.
  • AutoMD Member
    AutoMD Member - 1998 Mercedes Benz S320 - Engine - 4/7/2014
    Leaking reservoir who to approach initially
    how does one start off,from under or what? can it be repaired or replaced?
     
    • Jimm
      4/6/2014 Jimm
      First question - is this referring to the coolant system reservoir? If yes, the reservoir tank is easily replaced - utilize these on-line resources and guides; www.pelicanparts.com/techarticles/MBZ_Tech_Index-W203.htm

      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, www.partstrain.com - to list only a few possibilities.
      In fact, they (RockAuto) list the coolant reservoir (coolant recovery / expansion) tank from around $39.70 for your vehicle. Use the Uro part # 1405001749 - or equivalent.

      Here are the details and replacement steps involved;

      Over time, the coolant expansion tank tends to turn yellow with age, become brittle forming micro fractures and sometimes leak. When the car warms up, both the heat and pressure of the coolant starts to attack the weakest point of the tank, eventually causing it to fail and the car starts leaking coolant. The good news is that the replacement tank is relatively inexpensive and can be changed in less than an hour.

      Take a look around the coolant tank. In some instances, you can instantly see it has been leaking. In others, you may only see a faint trace of coolant weeping/staining the crack or seam. It's important to tackle this problem as soon as possible. Warning: Failure to repair or replace a leaking cooling system component can potentially cause a catastrophic failure damaging the engine.

      A couple of safety precautions / instructions you may want to observe before beginning:

      1) Allow cooling system to cool down to a coolant temperature of less than 90°C.

      2) Open cap of cooling system slowly; turn a conventional coolant cap as far as the first detent and turn a screwed coolant cap approx. 1/2 turn and release the pressure.

      3) Wear protective gloves, protective clothing and eye protection.

      4) NEVER pour coolant into beverage bottles, cups, etc... Someone might accidentally pick that cup up and start to drink.

      5) If you are going to be replacing the tank you might as well replace the coolant as well, as there may be the chance contaminants got into the tank and fluid. If it is an emergency and you need to get the car right back on the road it is possible to remove the coolant from the tank with a turkey baster and just replace the tank and lost coolant, but I recommend doing it right and draining the coolant. Even with the coolant drained you should expect a little spillage when removing the hoses, so be prepared for it.

      Step1) Begin by safely jacking up and supporting your car. With the car safely off the ground you will need to remove the engine tray. There are six 8mm bolts holding the tray on, the rear two also help hold the transmission tray. If you are going to leave the transmission tray on, remove the rear two bolts first, lower the engine tray, reattach the transmission tray bolts, then remove the remaining four bolts on the engine tray.

      Step 2) With the tray removed you will see radiator drain plug on the lower left front of the car. Place a catch bucket or tray under the plug and use a large flat head screw driver to open the drain plug. The fluid will come out slowly at first so open the tank cap to break the vacuum and help speed things up. The fluid drains out a small spigot facing rearward and not through the red plug.

      Step 3) From the top of the tank you will need to remove the 10mm nut on the upper right side. The tank sits in a plastic slot in the firewall that helps support it.

      Step 4) Remove the right side air intake to give you more room to work on the hoses. It compresses in towards the engine then slips off.

      Step 5) With the air intake removed you can now pull the auxiliary water pump from its mount on the tank (it just pulls straight out) , remove the coolant level sensor plug along with the wires for the pump and sensor from the bracket on the front of the tank. Next, you want to remove the hose connected to the bottom of the tank. If the hose is original it will have a compression clamp on it, simply squeeze it together and you may have to use a small screw driver to help break the seal between the hose and tank. Be prepared to catch the small amount of coolant that will spill out.

      Step 6) Pull the tank straight up, it may take a little force as there is a small rubber grommet it sits in on the bottom.

      Step 7) Take the old tank to your bench and if you where not having problems with the level sensor remove the old one by turning it 45 degrees and install it in the new tank.

      Installation is the reverse of removal
      Jimm
      4/7/2014 AutoMD Member
      great commentary unfortunately it was the windshield wiper reservoir is leaking and I have had estimates of 260$just to start and removing the front fender!!
    • Jimm
      4/7/2014 Jimm
      Did you access the website (www.pelicanparts.com) referenced previously - they offer many MB specific repairs and detailed steps; including the wiper washer reservoir replacement steps.

      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, www.partstrain.com, www.fcpeuro.com - to list only a few possibilities.
      In fact, they (FPCEuro) list the washer reservoir container from around $82.90 (genuine Mercedes part # 1408600260)
  • 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.