sukid35

I've got a problem that has stumped two dealerships so far, so I thought I'd see if anyone on the forum had any ideas. I have a 2003 SL55 with 28K miles and covered with a Fidelity Warranty. I've owned the car for about 5 years and it's been a great car. It's got every option I'm aware of for that year, including keyless go, distronic, etc. I had the starter battery replaced at the dealer's recommendation back in 1/2011, although it never gave me a problem. The car spends a lot of time hooked up to a trickle charger for the aux battery because it's a 3rd car and doesn't get driven regularly (but at least every week or two). Last summer, I went out on a Saturday afternoon to drive it to run some errands and it wouldn't start. I would get like one turn of the engine, but no start. Did not seem like a battery issue. It continued to do this many times over several hours. I used both the key card and the regular key and the outcome was the same. I called MB roadside and they came out and confirmed it was not battery-related, and recommended I have it towed to the dealer on Monday. On Sunday morning, I went out to the car, and it started right up. I drove it to the dealer that week and left it for a week, asking them to check it out. They did many tests, including fuel pressure, and changed the fuel filter, but could not recreate the problem or find any issues whatsoever. That was maybe 9 months ago. I've driven the car many times (weekly) since then and have no problems. Two weeks ago, I decide to drive the car to a work event, about 35 miles from home. It was again a pretty warm day, and they car sat in the lot for about 8 hours, until I was ready to go home in the afternoon. Car won't start. Same symptoms as last summer. I tried several times over the course of 1/2 hour or so, and finally called MB roadside for a tow. It ended up having to wait for 4 hours for the tow truck to arrive, and I tried starting the car at least a few times every hour. The next morning, the service advisor called me (different dealership than when I took it in last year) and asked me what was going on. I gave him the details and he called me back a short time later and said that the car started with no problem. They kept the car for two days and said they could find no problems (there were no codes set either time) and asked me to come get the car. I've driven the car 5 or 6 times since this last occurrence and no problems yet. But I'm having a hard time enjoying the car, with the constant worry of when this will happen again. Any ideas out there? I know the crank position sensor was a problem for some, but that's typically a problem with a hot car, and both times this has happened when the car has sat for 8 hours or more (although the exterior temps are probably 80-90). Thanks for any advice!

alx

you said when it happens it cranks once over, but no more?

or it cranks alright (a few times) and then when it starts it kind of turns over once and stalls?

when it happens does it throw codes?

sukid35

No matter how many attempts to start, it just does a semi-revolution of the engine each and every time. It doesn't grind or linger, and the attempts don't get more feeble with repeated attempts (like with a weak battery). And no, never any codes which is really frustrating.

carlsturm

This could possibly be starter motor problem. If armature has a worn spot and previous start positions the dead spot so it can't make electrical contact then starter won't crank.

This was my problem on previous car. Striking the starter motor with hammer would eventually orient the armature just right and car would start. Hey, nothing impresses your date like pulling out a hammer to discipline your car.

B R

This is true, I had some intermittent starting problems with my Qvale, so I changed the starter out & never had that problem come back.

alx

There is an electro magnetic clutch on your starter. It is possible that it is dirty and gets stuck every now and then.

Also check/ clean/ tighten your starter battery terminals.

Lastly it is possible that your key module is going bad.

Those are the options that come to mind.

sukid35

Thanks for the great advice so far. Next time the car goes in, I'll ask that they check the starter, check or clean the clutch, or even change it if it's practical. I'd feel better having done something that gives me hope than just waiting to be stranded again. I have checked the battery terminals and made sure everything is clean and snug. This most recent dealer did suggest that the problem is possibly tied to the keyless go, but I really pray that it isn't. That doesn't sound fun to troubleshoot, especially when the problem is intermittent.

alx

Humor me- use your other key for a while and replace its battery.

Just another random thought.

sukid35

When I took it in last year, my advisor told me to take the card and key I had been using and put them away, and use the spare ones. I'm pretty sure I did that. I did it again last week after this most recent occurrence, and right after that I got a message on the dash that told me the batteries in the card were weak. So I swapped them. I just ordered more of those batteries so I think I'll change the ones in the key right now....

cal1

I would still be suspect of the CPS especially in a 03. I am not sure when, but the CPS had enough issues that it was redesigned. Maybe alx knows. I just replaced my CPS a few months ago. More often than not, it will not fail for the dealer when they have the car.

alx

Cps act ups are common when engine is heat soaked.

Anyway, they are cheap to replace and you have an old car so you mIght as well have it replaced and get it out of the way.

My vote is either starter relay/ clutch or ignition key module.

sukid35

Thanks for all the advice, can't tell you how much I appreciate it. I have a nice list now for the next trip to the dealer. Whatever the problem is, it is so far always rectified by an overnight rest, then the car starts fine the next day. Dealer says they can't help me much unless they can observe the problem in action, which I never seem to be able to make happen. By the time it gets to them, things are working perfectly. At least now I have a few things to ask them to check/replace.

alx

i hope your dealer is doing it anyway, but ask them to run a full "quick" test on all modules. those cars have dirty minds and log a lot of problems (soft failures "-f-" (largely unnoticed) as opposed to hard failures "-F-" which usually trigger indication on dash board).

something must be logged somewhere. hell, they log things even when they work just fine

sukid35

Thanks alx, I've added that to my list!

sukid35

One other thing I should have asked up front is if there is anything I can to work around or troubleshoot the problem if this was to happen again. I believe a hammer was mentioned? I'd be interested in there was some rudimentary testing I could do (to pass info along to the dealer), and I'd also be interested in a workaround that might allow me to get the car started and get home. I'm willing to leave a hammer in the trunk as long as I knew what to pound on (besides my head).

alx

please do not hammer anything...

disconnecting and reconnecting one (or both) batteries is the only thing that comes to my mind in trying to unstuck the car.

CHP_H8_ME

Sounds like what happened to mine, very frustrating. Crank sensor fixed it...

cal1

There have been times when I thought carring a sledge in the trunk would be a good idea.

One more thing to add on the CPS. I know of at least one dealer that is willing to apply heat to the CPS to create a failure. They then have the info needed to show a warranty company why it needs replaced. You might consider mentioning this to your SA. We all know they fail often, just never in the shop. If the CPS is not your current problem, there is a good chance it will raise its ugly head at some point and you will most likely be in BFE when it happens.

sukid35

Excellent advice, thanks. I almost disconnected/reconnected both batteries when this most recently occurred, but I wasn't sure what other types of problems I would cause myself with the radio, etc. On the CPS note, I do have an SA at a dealership about 1.5 hours from here that treats me very well. I'll bring up the CPS heat idea. I avoid the local dealerships as much as possible, for too many reasons to go into here (Austin, TX).

damian155

Just curious if you ever found the reason for the starting issue. Im having similar problems now.

tthorne

Replace the crankshaft position sensor.. 35 dollar 30 minute do it yourself if you have any skills causes intermittent start conditions.