[dbmoylan]

Would anyone have personal knowledge on the procedures to replace a M104.990 engine camshaft position sensor?

Specifically, if just replacing the sensor, does it require resetting the air gap w/ the camshaft (which requires taking off the valve cover I believe?

Also, does the new camshaft position sensor have to be aligned w/ a particular setting with the camshaft when installing, or will replacing and using the factory supplied shim on the engine already be sufficient (provided the replacement sensor is exactly the same as the one being replaced)?

The camshaft position sensor has 2 5mm hex bolts holding it on the left front top of the engine, and is simply a magnetic sensor.

Thanks!

 

[dbmoylan]

Dietrich, thank you for your post. I am looking at changing because I've addressed almost everything else in the LH system that feeds my computer w/ info. I am trying to stabilize a condition which sometimes I have good acceleration & other times not. I noticed also a slight rpm drop while in gear and stopped that occurs w/in 15 seconds, then every 30 seconds therafter.

The car is a 1993 300SE/W140 chassis/M104.990 engine. For the past 2-3 years I've changed many small items like the MAF, O2 sensor, spark plugs, wires, rotor & distributor, fixed vacuum leaks (i.e. purge valve recently), checked other systems for leaks, replaced oil breather hoses, replaced the electronic throttle actuator, fuel regulator, wiring harness & had injectors tested & cleaned. Recently also changed the fuel filter & 2 pumps, and confirmed 48psi fuel pressure.

I was reading that a failing camshaft position sensor could give bad readings to the computer as it helps to control fuel injection timing. The crankshaft sensors I understand are more towards a start/no start situation, which is not a problem I'm having.

I recently spent an evening trying not to damage the 2 5mm hex bolts that sure as heck did not want to loosen. Luckily I was able to do so after much effort & patience. I did not know how to test the camshaft sensor, and decided to eliminate the problem by replacing it, hoping to improve the up & down performance.

Upon looking at the sensor, it looked OK, and not broken at the measuring end. When I get my replacement part I will do as you recommend. Understand that I don't have to align anything in particular when I reinstall, just be sure to replace shim (for air gap purpose) and o-ring for oil leakage & tighten 2 mounting bolts.

I appreciate your thoughts. Thank you.