occasional long crank time to start
 

My car generally starts without issue or drama. However, on a few occasions in the past few months (very rare), it will crank several times before it roars to life. The CEL does not come on at all. All the other times, it cranks once and fires right up.

For example (and this is the most recent one since it just happened this evening), the car started at home just fine (first crank today) and then took a short drive (10 minutes) to local shops. When I got out of car I noticed I had pulled forward too far into the next space (360 is on wish list for next car). So I jumped back in to restart the car and reverse a couple of feet and it took a few seconds (maybe 4-5) to crank. Other times it's happened that I can recall were in the morning after a short trip and then restarting the car about an hour later. However, more times in the same situation (short drive, an hour later) it starts right up with no delay.

Again I should stress that this rarely happens so it is just something I am keeping an eye on for now. Any advice?

Possible crank position sensor going bad.

+1
Same thing here , even tho i got a new battery and had my starter replaced couple years ago.
makes me wonder if the new starter is going bad or something else is up.
would be nice to figure this one out.
also noticed i had that happening more often with bosch spark plugs. (Probably not related anyhow but is what i have observed)

Thanks for the feedback. So if it's a sensor then the problem would become more common before it fails. I still have a couple of years left on my extended warranty (non MB ELW) but without a consistent, evident problem there is no claim.

Did you check to see if the CPS has thrown a code? When my CPS was failing in the W211 it had thrown an error code that was logged on the times my car failed to start normally. It is a cheap part, but placed in a rather difficult spot to achieve easy access. I had bought the sensor and had my indy replace it.

I will check to see if my reader picks up a code. Doubt it - I think it only does CEL codes. I think I would need the MB diagnostic system to read any logged error codes.

If it doesn't show up with my device, I will have a chance for indy to check when I get my brakes done. It will be interesting to see if it shows an error for that.

The good news is that the problem didn't occur at all yesterday or today. About 10 starts since it last occurred with many just a few minutes to an hour apart.

Mine was doing the same thing last year and the battery was the culprit. Every now and then it would take a few seconds of cranking to start the engine. One day after 5 or 6 starts and stops in less than 1 hour while running errands around town, it wouldn't start at all. It didn't throw any codes, not anything a generic scanner would see anyway. The cure was recharging the battery with a Ctek smart charger. I used the battery "rejuvenation" program these things come with for a few days and it's been fine ever since. I occasionally top off the battery every couple of weeks, especially when I only drive locally very often. The W212s have a dumb charging algorithm which will kill the battery if the car is driven short distance with many engine start/stop sequences frequently.

My battery is about 3 years old and perhaps it's getting a little long in the tooth for Florida. My Honda goes through batteries every 2.5-3 years down here like clockwork and that car's alternator always puts out 14.7v unlike the MB. Unfortunately because this long crank issue isn't happening consistently, I can't just charge the battery and see if that fixed it. Maybe if there are no stored error codes for the CPS then I can focus more on the battery. Or wait until there are more consistent starting issues or other signs of a fading battery like short convenience time after the engine is turned off.

I do love my ctek 4.3 charger so I am ready if the battery is an issue. I do a 'normal' charge cycle with the ctek every 6 weeks to try and compensate for the smart alternator. The last time was 4 weeks ago. I haven't done the 'recondition' cycle on the battery as it is best to remove from the car for those due to the higher voltage used.

Mine was 2.5 years old as well( manufacturing date July 2015) when it got discharged and wouldn't start the car. I wasn't charging it at all before it died on me because I didn't have the Ctek at the time. After running the reconditioning routine a couple times ( negative and positive cables detached but battery still in vehicle - a dumb practice because it could potentially spill its guts when it gets hit with 15+ V) and regularly hooking it up to the charger I haven't experienced the delayed start at all. It's been 5 months now. At first I was looking at the fuel distribution system as a possible culprit or some sort of electrical gremlin but couldn't find anything due to occurrence inconsistency or any sort of obvious fault. The battery for me was the last place I would have looked, I thought it was cranking just fine.
I didn't know heat kills batteries, I always thought it was the cold that gets them faster. I always lived in colder climate areas though so I have 0 experience with how heat affects accumulators.

Need help
 

did you ever figure out the issue my Mercedes does the same thing and it’s driving me nuts

I think I ended up getting a new battery and it solved the issue. Could be the starter getting old and need more amps to crank, but it worked fine after a fresh battery.

I had a similar issue too - I ended up with a Oddessy Battery and 16oz of MotorKote...starts awesome now...
I have the starter ready if needed - but my car is still under a service contract so figured i'd do things they would tell me first might be bad...

Good luck with your fix...
Cheers
JPC

Here's a previous thread on this topic - https://mbworld.org/forums/e-class-w...2010-e550.html

My second starter recently began giving problems (car is now 11 years old, 125k miles, e550 NA), in this case it turned the engine over just fine but occasionally the engine wouldn't start. The starter is inexpensive (this time I bought with lifetime replacement) so I bought another and replaced it. The new one really kicks the engine over and it starts way better, I don't think the previous two starters were ever this good. While a stronger battery helps for me that was not the root cause.

Peter

Yes, it is not the battery though fully charged battery helps.

The problem is the starter that robs too much amps when cranking the engine and there is not enough battery power left for the other needed functions to get the engine running.

I’m having similar issue in my e550 coupe 2010. Every mechanic I ask says it can’t be the starter because a starter would not cause long crank it would just click. The dealer has no clue and keeps saying I need to put an mb brand battery in the car even though the battery is like 4 months old. The battery does read low voltage sometimes however but so did the previous battery. I am convinced it’s a bad starter because they put a remanufactured one in my car and this problem started shortly after. It gets progressively worse. But I am always able to get it to start by tapping the gas pedal during long cranking.

Do a simple troubleshooting step. Charge the chattery full, I mean full or use another car with full battery running to jump yours and see if it makes a difference. If it starts better with totally full battery it most likely is the starter.

I had long crank issues with my 2010 E550 and it all got fixed after I replaced the starter and yes, it cranked just fine with the faulty starter but had trouble firing up.

I probably mentioned in my earlier post how I replaced the battery twice before replacing the starter. Each battery change helped for few weeks until battery charge went down under the smart charging system in the car.

im on battery number three as per dealership request, luckily they were all replaced under warranty but I’m fairly sure that is not the issue. My story sounds a lot like yours but my issue always presents itself with long cranking… you had hard starting or long cranks as well yes? Everyone seems to rule out the starter because of the long cranking symptom. I am suspecting it mainly because they put a remanufactured one in and I feel it has never been good. Even the starting note it makes is very weak although it sounds better after a battery recharge.

Arrie is right, it's the starter. For mine I ordered a rebuild kit from the dealership (~$40) and repaired it myself. I cleaned the commutator surface with 600 grit sandpaper and the grooves with a pick, installed the new brushes and it made a huge difference in how the car starts. I had previously replaced the battery thinking it was the culprit but it turned out it was the starter all along.
It's been 2 years since I've done that and I have no issues, and I'm still using the old battery (3 years old now).

Is there anyway to test the starter? I feel like I may have to prove to the dealer it is in fact the starter for them to change it.

I don't know of any procedure that would definitively point to a faulty starter. There might be a way to measure the resistance over the brush/commutator ensamble but I don't have reference values for comparison. You could measure the voltage drop when cranking, Amazon sells a few nifty tools which can test your battery capacity but also perform this measurement. I tried it on my Ford and saw that it drops to around 8V as the lowest value during cranking. It has a waveform function which does this. Mine is a Konnewei KW681. You could measure with 2 brand new batteries, if the drop is lower than 6V both times then you know the starter is drawing too much power during cranking and that's more likely your culprit. I can get a baseline on mine if you need one.

thanks I will try this. I know there’s a special mode on the cars dash screen that lets you view battery voltage. Not sure if it allows you to view it while cranking though.

Why would you need to prove your dealer anything? If your car is 2010 model it is not under their warranty so you will pay for the repair, right? Just tell them you want the starter replaced, period.