So today i go to start my car and it just turns over for a period of time and then won't start. I try again and again.. Finally the car starts right up and runs fine.. I was a little concerned, but not too worried. Then this afternoon in the heat of the day, I tried to start the car at a friends house, and it would not start.. It turned over but no start. I tried over and over. Finally it started and i was able to leave...
Then it performed correctly until tonight when i was backing into the garage, it did it again. I must say that when i open the car up the temp rises to the 3rd mark ( the mark above the middle) and stays there for sometime until it finally falls. I have bought a PTE thermostat and plan on installing it soon. I never had this problem in the winter. Could this be a heat related issue?
What could cause this. There are no check engine lights, and i am seriously frustrated.
Anyone else had this issue..
Even though it hasn't happened yet, i am worried about if it shuts off while i am driving, and i loose throttle/braking capabilities.....

Thanks for any and all input..
Nick

 

It could be a faulty fuel pump. My car was doing the doing the same exact thing. It would crank but would not start. After 2-3 tries it would start and run like a champ. Took it to the dealer and they said it was the fuel pump. Replaced it and never had another problem. Hope this helps.

 

So today i drove the car to get breakfast and back home and didn't have a problem. Then i went to leave the house and the car won't start. I tried and tried, waited, and tried some more. When i turn the key over, i can hear the fuel pump turn on for a sec like normal. Also, i have checked both the fuel pump fuses and they are ok. When i have the fuse door removed from the storage compartment behind the pass seat, i can hear the fuel pump relay click on and off with turning on/off the key, so i think the relay is good also. If i had to guess, i would say that i have fuel delivery problems somewhere though.. Could it be a dirty or clogged fuel filter? I have no idea when the last time it was changed, but it has been a long while for sure....
Also, i now have a check engine light, but i am sure it is going to be something like the car turns over and fails to start, so i am not sure it will help in figuring out my problem...
So unless someone comes up with some other ideas, i am going to start with replacing my fuel filter first...
Thanks again for any and all input..
Nick

 

Sounds like the crank positioning sensor is failing. Same thing just happened to me. We left the restaurant after about 45 Min, and it wouldn't start...just cranking...Called roadside service, 30 Min later, he gets in, and it fires right up! He tested both battery's, and they were OK. Thats when he mentioned the crank sensor. When it starts failing, it does it when it gets hot. (as you know, the engine will get hotter after you shut it down) After it cooled down, it would start. From what I understand, if it doesn't sense TDC, it won't initialize the fuel pump or the coil pac (pacs?) Although kinda strange, 'cuz I could have swore I heard the fuel pump energizing...
Replaced for $300 P&L...starts every time now...

 

Thanks very much..The part is very cheap, and i have heard the install takes about 5 min or less so i will go ahead and order one...The exact symptoms to refer to are what i am dealing with...Thanks very much..
I hope this may solve my problem...
Nick

 

wow good to know for future reference...thanks for the tip on the crank postioning sensor. If this part is going bad does it throw any code at all?

 

Yes it will give a code. (my CEL would sometimes be on then off) When I brought it to my mechanic, he immediately hooked it up to what I assumed was a "star" diagnostic "box", and after about 5 min or so, the display said something about the crankshaft sensor being "bad". He said he's seen them last 100K miles without fail, or fail @ 30k, just the luck of the draw I guess. I'm sure I can ask him what the specific error code was and he'll tell me. I wasn't planning on coming across someone having the same symptom's @ the same time I did I'll have to pay more attention next time! I'll follow-up shortly...thx

 

Sorry to hear that...a 2008, and it already needs a fuel pump?!?!!?

Darn "Chrysler's"!!!!!!!!! (glad your up and running)

 

Well i replaced the fuel filter (Holy **** what a pain i the ***> It is on the drivers side rear ABOVE the differential), and went ahead and installed my PTE thermostat. It runs a little cooler, but i was expecting a drastic change. The temps stays directly in the middle of the 80C and 100C mark after wide open throttle (It used to stay on the 100C mark). It does come back down to the 80C very slowly after a long period of cruising.
Does anyone know at what temp the fan is supposed to come on? Mine would get to the 3rd mark before the PTE thermostat and the fan still wouldn't turn on. In fact, i thought the fan had a blown fuse or something until i noticed it runs when i turn on the climate control system. Could a fan turn on sensor be bad? and why wouldn't i get a CEL code for it? Also i have heard that these radiators get clogged with higher mileage cars. Do you think i should replace my radiator?

On a separate note, i ordered the Crankshaft sensor it was only 40.00 shipped online for a Bosch part. Also i don't believe it will be difficult to install. I found this online>
"To anyone wondering, installing a crank position sensor on the SL55 is easy as cake. 5 minute job, driverside behind the valve cover near the firewall. E8 Torx Socket."

 

OH yeah, about the fan, just thought i should mention the last time i was at the dealer i asked them to do the fan mod with STAR to make it come on 10 degrees cooler. They said they did..

 

Well i think i may have spoken too soon about the PTE thermostat not having a drastic effect on my operating temps. I think the system just needed to be burped a couple of times after installing the thermostat. This morning it took longer to reach 80C and then stayed there. I made several WOT runs and the temps didn't rise considerably at all. Pre-PTE it would have risen to 100C in no time. So it is definately working much better than stock (I didn't notice the effects of heat soak at all >It was very prominent before)...
Anyway, just thought i should let everyone know...

Nick

 

Just thought i should post a follow up....
Today after working out, i tried to start the car and it wouldn't fire. Just turn over and over...
What's ironic is that my new Crank Position sensor just came in today... I decided i would just let the car sit up at the gym and cool for a few hours so i called a ride. That way i wouldn't have to install my part in the gym parking lot, but instead later tonight in my garage after the engine cooled... So i wait 3 hours and go back to the gym (with the new crankshaft sensor and tools needed just in case >Pliars, various extensions, universal joint, socket wrench, and E8Torx socket). The engine had cooled considerably when i got there so i tried to start the car... It wouldnt start. Tried several more times and no fire... I decided i would have to be a parking lot mechanic and so i took off the engine cover, drivers ram air duct and filter assembly.. I looked behind the drivers valve cover and couldn't find anything. I looked all over that engine and couldn't find a sensor anywhere. I decided to button it all back up and come back later when the engine had further cooled, but i decided to try it 1 last time.. To my surprise it fired up. Well i was on my way home to post the question of where the sensor is actually located, and the car died in the middle of the entrance to my neighborhood and wouldn't start back up... Now i began to get upset. I removed the engine cover and ducting again and looked for anything that had wiring going to it behind the valve cover. I couldn't see anything. In desperation i stuck my hand carefully behind the drivers valve cover (while the engine was still hot) and i could feel the sensor and connector. FINALLY, i was getting somewhere. I got the harness unsnapped and using a series of extensions and universal joint, i was able to get the torx bolt out and swap out the old sensor for the new. This was much more difficult than i expected, but do-able on the side of the road. I got everything buttoned back up and the car fired right up.
I don't want to get too excited, but the car starts up just fine now, so i think i finally got my problem sorted (knock on wood). Anyway, to anyone having these starting issues, buy a new Crank position sensor and swap it out before you get stranded ( the car will cut off while driving).. Also, do the swap on a cold motor...

Nick

 

Nick...excellent write up...very insightful and informative...and scary at times (stranded...nobody wants that!) please give us an update after a couple of weeks of driving so this symtom can be linked to it's fix without any doubt.

 

hmm,,,,it's my turn,,,the car wont start,,,,,i tried to start over and over again,,,,,but all i hear is a few click,,,,,,and nothing happen,,,,,,all the light turn on as usual, but car won't start,,,,,will have mercedes check tomorrow

(would the dash diplay some sort of message about the problem)??????
could it be low battery???? starter problem???

 

Its got to be a low battery or bad starter solenoid.. I would check the battery 1st and charge/replace if neccesary.. Then move on to starter solenoid..

My problem was definately the Crank position sensor. In my case the car would turn over fine, just not start up...
Good luck..
Nick

 

can i ask what do you mean by "car turn over fine"? i was thinking low battery too, but all the interior lights came on though

i think i am the one sold you the pte thermostat

 

By turn over, i mean when i turn the key, the starter motor would begin spinning the motor as if to start the car. However, i wouldn't get ignition. The motor would spin and spin and not fire...

And yup, I got the thermostat from you...

Nick

 

Found the problem, it's the starter battery,,,i am feeling relief,,,,,I thought it might be something more complicated than that,,,,,,,,,shoulda replace it myself though

 

No problem...my mech made it sound like it was hard to get to...$200 later, and all is back to normal. Next time I'll check-in here first! Glad that was all it was

 

Pretty sure I just got this on my new SL55. I have been noticing noise from the fuel pump as well which sounds nothing like the SL55 I swapped out of 3 weeks ago.

Anyway I was stranded on the side of the road for 10 minutes tried starting the engine about 10 times. It turned over and over but didnt start. After a last ditch attempt it fired up and I had a check engine light as well. Drove the car 2 miles home keeping her under 1500 rpm and parked her up.

After 1 hour I came back out to start it up and it started fine and the check engine light went out! I HOPE that it logs the fault so I can take it to Merc and they can find out what the issue is tomorrow.

Is replacing a fuel pump on these cars a big deal?

 

I had the exact same problem yesterday with my 03 sl55. i did a quick search here and did not find this thread...I towed the car to my mechanic and he mentioned the crank sensor....he is replacing it tomorrow.....If I found this thread yesterday I would have done it myself...now looking at $180 for the part, add tow and labour...so hopefully it will be less than 400

cheers

Paul

 

Too bad you found the thread a day late. CPS failure is very common. There is even a good DIY on replacing it here. Sounds like you will be up and running tomorrow it is just going to cost you a bit more.

 

Mine was also the Crankshaft Position Sensor. I watched a DIY video (slightly different procedure for my car though as it's a different model) at
I ordered my part for about $20 after Googling to find the best price.

It's been about 3 months now, and the car starts every time.

 

cool! Glad you got some value from the boards. By the way, I was talking to an MB tech the other day about CPS failure and he said the newer design, which you undoubtedly got, seems to be bullet proof.