I've had the car not start 2 times in the last month. Each time, I've let it sit for 15 minutes and then it starts, but the check engine light then comes on. I then remove the engine cover and reinstall it and the check engine light goes off. Since about 2 weeks prior to the no start issue, when I put the transmission into neutral (I have a manual) it hangs at 1,500 rpm for about 5 seconds and then drops back down. The high hanging idle is also a new issue. Does anyone have any idea what might be occurring?

A little further background, my valve covers (the small upper valve covers) are leaking and need to be removed and resealed and reinstalled. I have not replaced the crank shaft position sensor, nor the camshaft position sensor, and have not re-soldered the RCM yet. I will be tackling these 3 fixes in the spring, but I don't think that these symptoms match any of those experienced with those issues.

Thanks for any help!
Jeff

 

Use a scan tool and pull the codes; When the car did not start was the engine hot or cold. If hot, crankshaft position sensor is likely problem.

 

Hi Zip! It was hot...okay, I'll move forward with replacing the cam and crankshaft position sensors as they need to be done. I will also scan the codes and if there is anything odd I'll update the thread. Thanks for the insight, much appreciated.

 

Hot engine would not start, if that means the starter engaged but the engine did not start - AND the CEL came on - but it started when it cooled off?
Classic indication you have a Crank Sensor going flaky.

If the starter would not even engage - re-solder the suspect points on the RCM.

 

This is exactly what happened. The starter had no problem cranking the engine, but it just would not start. Once it cooled off, it started like normal and the check engine light came on. Thanks so much for the help!

 

Replaced:
1) Crankshaft Position Sensor: Bosch 0261210170
2) Camshaft Position Sensor: Intermotor PC641
3) Re-soldered RCM (three posts)

New Symptoms:
Oddly, the no start problem is now more pronounced. The high idle is no longer an issue and the check engine light does not come on at any time.
The car does start and run, but intermittently will not start. The engine turns over; the starter engages and cranks just fine. It does occur more when the engine is at operating temperature.
When attempting to start, when the the key is returned to the off position it sounds like there is a very subtle back-fire - a very slight puff.
Further information: I replaced the Crankshaft Position Senor first and it started up perfectly (with the old Camshaft Position Sensor). I then replaced the Camshaft Position Sensor and the engine hesitated, I returned the key to off, then tried again and it started.
I don't have an OBDII scanner, so I am unaware of any codes. I will be purchasing one tonight.

I have made a youtube video of the problem which can be found below. It starts fine the first time...symptoms appear on 2nd start attempt. .

Thanks in advance for your knowledge and help!
Jeff

 

1) I'm, not sure you have a problem. There are a number of systems on the car all which talk to each other on the "CANBUS" wiring harness. you many be trying to restart the car so quickly ofter turning it off that the systems are not having time enough to settle back to their starting position. THAT IS JUST A WILD *** GUESS, but if the car is allowed to shut down and then wait at least ten seconds before restarting do you still have this no start problem?
2) Stay with Bosch or OEM Mercedes electronic replacement parts. Other brands have been know to cause problems on our cars. Camshaft part numbers are:
MB A004 153 6928, Bosch 0 232 103 050.
3) A code reader is a necessity with these and newer cars; otherwise you are really just taking guesses, perhaps educated guesses, but guessing non the less.
4) Change/fix one problem, part replacement at a time. Doing several repairs simultaneous just complicates the procedure.

 

 

You arn't kidding! BOSCH are the only sensors to be used.

Thank you Zip439 and onehundred80. It was the Intermotor PC641. I removed it and put back the OEM sensor and everything is now working fine. I will order the BOSCH sensor and replace it in the spring as it was clearly the Crankshaft Position Sensor that was the original no start problem. For anyone else referencing this thread, only use BOSCH sensors and I would suggest following Zip's advice of replacing/repairing each issue at different times so that if something goes wrong you know which component is at fault.

This forum is phenomenal and you guys saved me. Thank you so much everyone for your help.

 

BTW the cheap OBD scanners are just that, Cheap. Many OBD errors say "this just means there are errs in a module" to read the real codes you need a Mercedes scanner. The most cost-effective I have found is the with the BENZ module (not Chrysler) (on sale at the moment) and tell it you have an SLK320 with 16 pin.

 

Thanks for the heads up, Padgett. I was going to investigate what to buy and you took the guess work out of it. I'll pick one of these up.

 

If I were to pick up the Autel DiagLink would I tell It SLK320 for my SRT6 or wold I tell it SLK 32AMG? Is 16 pin the number of pins in the connector? Thanks