My engine turns over ok but wont start

[neiledgar]

Hi guys, thanks to those who answered my last shout for help!! i took your advice and searched for help by local engineers etc, but there are none locally that know anything about Mercedes Benz!! the curse of living in the sticks!!

But after searching through my repair manual it shows how to change the sensor(crankshaft position sensor) that you recommended was at fault, but it then says that WARNING if the sensor is not set re-initialised by a Sun Diagnosis centre, that the car may start but not run correctly? Now ive searched many forums, and posts, and no-one has mentioned this before. Are they just making me go to Mercedes for repairs, or can this sensor simply be fitted at home with no need for diagnostic resetting, has anyone done it at home without any issues??
I appreciate all the advice and help you have all given, i feel a bit on my own with this, when fit i used to be a motor engineer, but now disability and age are taking their toll and i dont have a lot of ability these days. The sensor on the 320 is supposed to be hard to get to, anyone got any advise or tips as to whether i should attempt it or not. Sometimes these books scare you with their warning signs, when really its not that bad, i just hope some of you guys have experienced this sensor and can shed some light on my situation. Once again, THANKS, id be lost without the MBclub and its trusty members!!

 

[AMGeed]

I understood these sensors to be plug and play. No need for additional diagnostics afterwards but I stand to be put in my place

The CPS is in a bit of an awkward spot, on top of the gearbox bell housing on the passenger side of the engine. I think its only a torx screw to undo, but there have been instances where the sensor has been difficult to remove.
Have a look and see if you can see it and decide then if you want to try it yourself.

It is something that should be done sooner than later as my experience is the cutting out gets worse if you leave it.

These two videos show how its done.

[YOUTUBE]/watch?v=2cYAVn639Pg[/YOUTUBE]

[YOUTUBE]/watch?v=JLOweWeLSYQ[/YOUTUBE]

 

[neiledgar]

Thanks for that, i understood that they were "plug and play" as well??? so we will see if anyone knows different! But i will have a look tomorrow, and see if i can get to the sensor ok. Its not to hard to remove all the top end covers and Maf sensor, and if i can bend to find the sensor it may be possible for me to do it, I do appreciate your input, its good to have someone to bounce ideas off!! Thanks

 

[AMGeed]

No problem Neil. Hope you can manage it.

Did you try to start the car from cold without problems?

 

[neiledgar]

Yes the car starts ok, about five minuets after it failed to start, it started up fine and has not done it since, ive run the car as normal and various stops and starts for three days now without fault, but, i do feel as you say it will only get worse if a leave it. Having checked things out, this fault is the most reported fault on this car and many others, so have taken your advice and ordered a new part. I will continue to use the car, all be it with worry incase it happens again, thankfully she has not started cutting out, she just failed to start that one time.

 

[optimusprime]

info

If you dont realy know whats wrong with your car .Get an Auto elec out to check it over first .I had all this and it turned out to be alarm problem .

 

[markmifsud]

The CPS is quite a common issue, and not just on MB. Normally fails after it gets warm, and stays failed until cooled down. To test you could give it a squirt of freezer spray once failed to see if it then works.

As has already been said, its plug and go. remove the single torx screw and the electrical connections and its job done. The only difficult part is getting in a position to work in the area.

 

[IanW]

I replaced the CPS on my CLK500 about 6 months ago. I can confirm that no coding/diagnostics was required at all. If it hadn't been for the swine of a location, it would have been a 5 minute job.

However, mine was retained by a reverse Torx bolt - Reverse Torx Single Socket E4 1/4" dr SKT-42604

A 1/4" driver with a flexible shaft also proved essential.

While I was there, I covered the sensor and wiring with a thermal tube to try to keep it a bit cooler.

Ian.

 

[neiledgar]

Thanks to all who have helped with advice, i agree about the thermal tube and i will follow that lead!!! Today i tried to access the sensor, my oh my she is in a difficult area, with my disabilities it is going to be impossible for me to get to it, and be successful in replacing it, but, ive located an engineer who says he can do it for me very cheaply, so all seems to be going ahead ok. It is in a very awkward place and would never have found it if AMGeed had not sent me the video links, they were fantastic and think everyone should get a copy of these on file, they are far better than the repair manual. I did cool the sensor down, and it worked quickly again, like markmifsud suggested, as you know the car wont start when its warm, but will start after it gets cold again, but cooling spray did make it start right away. Thanks to everyone, you have all been a great help, and now itrs on its way to being permanently sorted. By the way ive found a source for the sensor, came delivered at £34.96 and its a genuine same maker part, just ask for details if you need one. Compared to Mercedes at £119.00 plus vat and them £8.99 delivery, i think i got a bargain. But i will post on here to let you know if the new part does the trick, but im sure it will. Thanks guys!! the MBclub is a great community, and proud to be associated with you all.

 

[neiledgar]

hi, appreciate what you say, its always best to get things checked. This is such a common fault on these cars, (at least i found it out eventually) that it was safe to take advice from other members in this case, although, i whole heartedly agree with you, that everyone should get the motor checked diagnostically, as it could save you hundreds in the long run and loads of heart aches. Thanks Optimusprime for taking the time to answer my post, much appreciated, and your comment was worthy!!!

 

[neiledgar]

Hi Guys, just a quick follow on to my sensor woe's, I got a fantastic engineer who replaced the sensor for me, in double quick time. Ive now done 2,000 miles since it was fitted and the car is running a treat!! Im always a bit worried about OEM manufacturer parts, but in this case the item is fantastic!! I didnt realise how much the car was being affected by the sensor not working properly, by that i mean the car is running very smoothe now, loads more power and very responsive. The sensor must have been reading badly when it was on its way out giving me poor running. I did not notice it at the time but now that the new sensor is fitted it like a sports car!! My engineer did a little conversion for me while he was fitting it, after some advice from an MB club member, he made up a tube of heat resistant material, and attached it around the sheathe of the sensor wiring loom, and bunched it around the top of the sensor, and hopefully this may help in too much heat getting thrust upon the sensor. But anyway, thanks for all your help and advice guys!! but for now my C320 is 100%

 

[ALFIEBEARD]

If you want to locate a very good Mercedes Indie near you just nip to Carlisle off at junction 44 of the M6 right onto Kingstown Trading Estate then 2nd Right and 100yds on your left you will find Autotech they are Mercedes trained mechanics and have done a few very good jobs for me, at reasonable prices.

Alfie

 

[ALFIEBEARD]

Hi Guys, just a quick follow on to my sensor woe's, I got a fantastic engineer who replaced the sensor for me, in double quick time. Ive now done 2,000 miles since it was fitted and the car is running a treat!! Im always a bit worried about OEM manufacturer parts, but in this case the item is fantastic!! I didnt realise how much the car was being affected by the sensor not working properly, by that i mean the car is running very smoothe now, loads more power and very responsive. The sensor must have been reading badly when it was on its way out giving me poor running. I did not notice it at the time but now that the new sensor is fitted it like a sports car!! My engineer did a little conversion for me while he was fitting it, after some advice from an MB club member, he made up a tube of heat resistant material, and attached it around the sheathe of the sensor wiring loom, and bunched it around the top of the sensor, and hopefully this may help in too much heat getting thrust upon the sensor. But anyway, thanks for all your help and advice guys!! but for now my C320 is 100%

Hi Neil,
Thanks for the e mail, my car is a Mercedes S350 CDI Bluetec its my 5th Mercedes and I love it, I tried to reply to your e mail but it seems you have set your profile so you don't want to receive e mails lol. glad your car is now fit and well and you are again enjoying it.
Kind Regards
Alfie

 

[neiledgar]

hi, dont know what happend as it is set to allow emails and PM's to come through, so dont know whats going on so no matter, thanks anyway, pleased your close, makes it a wee bit more real than just internet based. There are loads of merc owners in this areas, we should arrange something and get together sometime!! have a drive out to a local watering hol;e or something!!

 

[neiledgar]

Just met a few other Mercedes owners who live locally here in Lockerbie, and everyone of them are interested in a regular meet, if any other people on here, within easy reach of Lockerbie, and would like to have a regular say....monthly meet at a local hostelry!! please message me!!