Here is a step-by-step guide on how to replace oil level sensor for Mercedes Benz.If you found you have a fail oil level sensor,just buy new one,then follow this guide to do it by yourself.
It will take you about 3 hours
Tool you need: 13mm wrench, 8mm socket, E10 Torx, extension, floor jack, jackstands, wheel chocks, safety glasses, torque wrench
And for more Benz project you can check here:Mercedes Benz Projects
Applies to: C350 (2007-14), SLK350 (2004-14), CLS350 (2004-14), CLK350 (2005-14), E350 (2005-14), S350 (2005-14), SL350 (2005-14), R350 (2006-14), ML350 (2006-14), Viano (2005-14), Sprinter (2006-14), CLC350 (2008-14), GLK350 (2008-12)
With the vehicle safely lifted and supported remove the rear engine/transmission cover by removing the six 8mm bolts(red and yellow arrows). The forward bolts also help hold the middle engine tray in place (yellow arrows).
Use 13mm socket and remove the drain plug and crush washer (red arrow).This bolt does not need a lot of toque but for some reason people really tend to over tighten the drain plug.Use care,as oil should be quite warm.
The flow of the oil will change as it starts to empty so don’t just put your drain pan underneath and walk away.
When all the oil has drained install a new drain bolt and crush washer and torque to spec.I do this now so I don’t forget.
Remove the sixteen E10 Torx bolts (red arrows).Unless the sealant has completely failed the pan will stay firmly affixed to the engine.
If you do not want to install the drain plug and washer at this point at the very least install the old one (red arrow) to prevent accidental spilling of oil out of the plug while you are removing the bolts (yellow arrow) and pan.
With all of the bolts off you will need to use one of them and screw it into the forcing bore,which is located on the front of the pan(red arrow,looks like a small nut welded on to the pan).This will force the pan away from the motor and help break the seal.
Use a series of wedges (red arrow) once the bolt has started separating the pan from the engine.The factory sealant has quite a bond so you may have to use a little heat from a hot air gun to help if you have one.Whatever you do,do NOT place anything metal between the pan and engine that could scrap or mar the mounting surfaces.Once the pan lets go be prepared because there will be a little oil left in it.Carefully and thoroughtly clean both mounting surface on the engine and pan.Also if sealant has gotten into the bolt holes in the bottom of the engine carefully clean these out.
With the pan off you can see the two parts to the oil level sensor;the connection to the wiring harness (yellow arrow) and the level sensor (red arrow).You can see in this image that the mounting surface of the sump has not been cleaned yet(green arrow).Do not reinstall the pan to a surface that looks like this.
Disconnect the wiring from the sensor by reaching up between the left catalytic converter and unplugging the sensor (red arrow).Try and clean this area,because once you pull the connection out anything around the sensor will fall through on you.
There is a small wire that runs from the sensor to the connection.This wire is clipped in place in the sump area.Use your fingers and unclip the wire from the mount (red arrow).
Use an E10 on an extension and remove the single blot for the connection piece (red arrow)
Push from above and pull the sensor out from bellow.Never pull the sensor out by the wire if you are replacing the connection for some reason always install a new O-ring (red arrow)
Use your E10 socket and remove the two bolts holding the sensor in place (red arrow)
The sensor is actually two pieces connected by a wire.Your replacement part should contain both pieces.Installation is the reverse of removal.
With the new sensor installed and everything clean and dry apply a small bead of sealant to the pan and install it.The torque value on the pan is very small so you do not need to worry about torqueing a crisscross pattern but I doesn’t hurt.I recommend Drei Bond.I have used this for years with great result,and it is available at Pelican Parts.Make sure to carefully follow the instructions on the sealtant you choose to use and allow it to dry and seal completely.
Also you do not need to use a lot of sealant.All the extra will d is squeeze out and make a mess outside and inside the cover.Installation is the reverse of removal,and do not forget to refill your motor oil!