bbirdwell

Happened yet again. First Crank Position Sensor went intermittent the first day I owned my car (77K miles). Last year I replaced the factory CPS with a Bosch sensor while cussing at the MB engineer who designed the CPS to install with the bolt downhill from the sensor!


Today, at 92K miles, engine quit going down the highway at 65mph on the outer loop. Thank God it wasn't in the midst of downtown traffic with no shoulders! Waited 10 minutes on side of road (just like the first time), engine cranked, drove it home, and pulled a new Bosch sensor out of the trunk. Less than 8 minutes to pull the suspected intermittent sensor and then approx. 30 minutes to get the E8 bolt started in the replacement sensor!


How hard would it have been for some MB engineer to say, "Gee, how about we rotate the sensor 180 degrees so the E8 bolt is on the uphill side, easy to see, the bolt won't fall under the car if dropped, and the sensor literally guides the bolt into the tapped hole!". Give the engineer a raise and a promotion! This M113 sensor location is poorly engineered but easily corrected if anyone at MB actually cared. If I ever have to pull the transmission this will be one thing I will modify at a machine shop.


FWIW, I replaced the Cam Position Sensor (factory OE) "just in case" it was the culprit and not the Crank Position Sensor (only 8 months and 15K miles on it). Belts off, supercharger idler pulley off, pulled I/C lines out of the way, replaced sensor, reinstalled everything. Call it 20 minutes start to finish for that sensor.


Another FWIW, Xentry showed no codes current or stored and the pathways to each sensor tested good.


I'm beginning to be disappointed in the vaunted MB engineering...I'll cut some slack as it could have been the Cam Position Sensor and not the 8-month old replacement Crank Position Sensor. I'll give it another year and reevaluate then. Nonetheless, this is the kind of thing that sours me on a vehicle.


Cross-posted at the other forum.

MiamiVice

MB is the only car Ive ever owned with this CPS issue and it is ridiculous. Assuming my engine is cool I can replace one in less than 10 minutes but WHY should I have to? BMW, Volvo, Chevrolet, Dodge, Porsche Ford, Nissan, Mazda, Honda! I have never had this issue with any other car. One thing I do know is you always buy the OE CPS--Ive had nothing but problems with aftermarket.

kponti

Considering that other manufacturers use very similarly spec'ed bosche sensors, I'll say the problem is the way the demands MB cars put on the sensor is to blame (engineering design). Just about every MB that has graced my family, immediate and extended, has had CPS failures while with us (and there has been a lot of MBs).
I compare it to the MB fuel pump issues of the late 1990s. Toyota used that same pump, MBs however managed to fail the pumps pretty consistently especially in the MLs

jmb614

You could put some tape on the socket to hold the bolt in while getting it started.

mkiv_tdi

Agree 100%. Almost the entire reason this job is so frustrating and takes more than 5min is due to the location of that dumbass E-Hex bolt beneath the sensor.

Also, for you guys that this has happened to.... what's it feel like??? What should I keep an eye out for when you're cruising at 75mph and your engine dies on you? Is it just like coasting and you're gliding to a stop?

Do we lose power steering and brakes??

2000UZJ

Power steering and alternator yes. Since the key is still in the IGN position the SBC should remain on since it's on it's own battery so no brake loss there.

I did 50 miles with no serpentine belt (it was pretty ****ty) and had brakes up until the SBC battery went dead.

Denroll

If you ever have to replace the MAP sensor, you'll face more frustration. Two bolts, but not enough room to get straight at them with a socket. A ratcheting box wrench would be ideal, but the bolt is too close to the sensor to allow the thicker wrench around it. Not enough room to get your hands down there to do anything. Doing this job was the closest I've ever been to throwing tools in frustration.

Or you can pull the supercharger and change the sensor in 20 seconds.