AMGCurious_702

So 6 months ago, I pulled the trigger on a 2017 C43 that has overall been a BLAST to drive. A few weeks ago I noticed the car was taking longer to crank after sitting overnight. I assumed it was the battery because the manufacture date on the battery said “10/19” and I live in a hot desert Climate were batteries Don’t normally last any longer than three years. So I bought a brand new battery from Interstate and changed the battery myself (not as hard as I thought it’d be)

After installing the new battery, the car STILL has a long crank when cold. Once it does get running and I drive it around, it cranks perfectly normal. Someone in a Facebook group suggested I “prime” the fuel pump which I did. And on a cold start, it cranked perfectly fine. I’m guessing something fuel system related? I’m trying to be proactive and not reactive so I don’t end up stranded somewhere.

Has this long cranking issue affected anyone else? 2017 C43 with 71k miles on the clock

C43Mike

This sounds like the anti-drain-back valve in the high pressure pump (or possibly both pumps) has gone bad. This used to be a common issue with BMW's that had the n52tu engine (twin turbo direct injected i6). I know it is the enemy brand but the direct injection functions the same and the symptoms match up exactly.

Whenever something goes out after the warranty period, it is time to upgrade. It sounds like you need a pair of e95 compatible HPFP's and a LPFP along with a high boost tune 😁

W205C43PFL

OP, can you film the crank and time it too for us to see to determine if it is normal or not?

AMGCurious_702

Yes. Next cold start I will do that

W205C43PFL

Let us know what is the outside temperature is when you do the start, is the vehicle parked outside a garage. Is the vehicle parked at an incline, etc.

AMGCurious_702

Current outdoor temp is 91 degrees F, parked outside, flat surface. Car has also been sitting for about six hours, made a short trip to the supermarket early this morning.

W205C43PFL

Hmmm that does seem longer than usual, when did it started? I was going to say when temperature's are colder it does crank longer that is normal but what I mean by that is when it is below 0 degrees which I mean. but... then I realized you said you live in desert climates.

W205C43PFL

Another thing is... does it long crank every single time after sitting overnight or only occasionally? You also mentioned priming the fuel pump, did it help at all or same thing and by priming the fuel pump you have keyless go and start right, so you just press it twice until all lights turn on and wait then foot on brake to start engine, right? If so, that procedure to prime the fuel pump is correct.

AMGCurious_702

started doing this maybe a month or so ago. As I think I said in my original post I thought it was the battery. When I replaced the battery and started it up, it cranked up and started quick no problem, but then after sitting awhile it started doing it again

AMGCurious_702

Before I replaced the battery it was only cranking long when cold (after sitting 8 hours at my job or overnight) once warmed up it was fine. Since replacing the battery, long cranks still occur but less frequent. Priming the fuel pump before starting the car makes it crank/start just fine as normal. The car had been sitting maybe 6-7 hours when I posted the vid earlier. I’m currently at work and will post another after sitting for a full 8 to see how it goes so you can see

W205C43PFL

My bad I must had missed it from your original post. Sorry about that.

W205C43PFL

hmmm, did you plug a scanner in and see if there are any codes, did you also ask your independent shop (if you have one) what it could be?

W205C43PFL

I read your original post before replying but I might had missed part of it for some reason, sorry about that, I went back and read it again.

That said, you made the right decision to check and change the battery first. I think it was a good start and if it happens less frequent after the replacement and it is not in your head then it (hopefully) might still have to do with the battery.

What is the voltage on the new battery when not driven for a day, what about after cranking and what about after 30 minutes (highway?) driving, etc.(asking because there is a possibility it might be a bad battery despite being new, it happens like bad batch) and is it getting fully charged or charged properly, everything good with the alternator right? What is the manufactured date on the new battery? Are you aware of any parasitic drain, do you have a hardwired dashcam, do you use a/c rest (residual heating). Confirm if the battery drained a lot of overnight in the morning.

What battery did you replace with (type etc. AGM, you got group H6 or H7 right? ) or is it an OEM MB battery? Although not always necessary, did you teach in the battery in Xentry diagnostics (doing so tells the car that a new battery is installed), this is not a must do step as we forum members changed batteries on our W205s without having to go through that step but WIS (workshop information) calls for it. What is the condition of the auxiliary battery? Let me know if your scanner picks up any codes. Check the fuses as well. Hopefully us forum members can help you figure it out.

White One

Umm, are the spark plugs, filters, etc original?..I have an '016 with similar miles, and it's the exact opposite. I do know my spark plugs were done at 100 km..

AMGCurious_702

You have asked a lot of good questions. I’ll answer the. In the order you asked.

1) When cold, I hooked up my battery tester to both the charging terminals, as well as the battery itself. Car not running. I got 2 different readings

Here is the battery reading when I hooked the tester up to the charging terminals. Car sat all night, engine not running

Here’s the battery tester reading when hooked to the actual battery. Cold engine, not running

EDIT: Will test the battery after my drive home from work tomorrow (30 min commute) and get back to you on how everything tests

2) This little $10 Walmart battery tester tests the alternator also. Pic below

The car was running here. The alternator read the same both on the charging terminals and the actual battery itself

3) I don’t know the mfg date on the battery. I didn’t think about that when I bought the battery. I bought it from directly from Interstate. 36 month warranty. Will check next chance I get

4) No parasitic drain that I know of. No hardwired dash cam. No residual heating as far as I know. Never heard of ac rest? What exactly is that and how can I tell if my car has that?

5) It’s an H6 battery I purchased directly from Interstate

6) I don’t own any Xentry equipment but I did use an OBDII reader made specifically for Mercedes-Benz called Autophix 7770 and programmed in the new battery via the front SAM

7) I did a full health scan with the Autophix 7770. Nothing battery or electrical related came up. Car had a clean bill of health.

8) As for the aux battery, I don’t know what kind of condition it’s in. I actually didn’t know AUX batteries were a thing until I bought this car. It’s my first MB and my first AMG

i don’t think I missed anything you asked. Please let me know if I did and I’ll give you an answer. Btw, you’ve been awesome, super appreciate your help/advice

W205C43PFL

Yup you answered everything I asked except fuses, just want to make sure, did you check those by chance? Sometimes, fuses that blow don't really show up as codes in the ECU, at least that is my experience. For the W205, I remember there were fuses where the front passenger footwell is and there are another set of them in the trunk beneath the floor cover, I forgot if there were some in the engine bay under the hood, there might be. If you are stuck, there are fuse diagrams where the fuse box is in the trunk.

I am sorry, I should had put those questions I asked in point form as reading back what I wrote, I realized it is all in one big clutter of sentences. Glad you still were able to answer most of my questions, thank you as that will help us help you.

Yes the residual heating is basically the a/c rest thing (it is actually separate, meaning the residual heating is really called "Rest". Sorry for the confusion as what I mean by "a/c rest", I am referring to the button. Further to that though, I do realized it is not available in your car, it is more like an European market feature, but essentially, it is a feature you activate to allow the vehicle to use the residual cold air (during a hot summer from the a/c) or heat (during a cold winter from the engine) from the climate control system to maintain the vehicle temperature or at least slow the rise/drop of the cabin temperature for 30 minutes (and of course the actual a/c isn't going to be running but it is better than nothing), then it will turn off, that however drains the battery quite a bit. Image of the button I am talking about: https://cdn-ak.f.st-hatena.com/image...1123184721.jpg

As for battery voltage, hopefully this chart I found shared courtesy of another forum member helps: https://mbworld.org/forums/gle-class...ml#post8745111

For battery voltage testing, did you try different meters just to make sure the voltage that it is reading is accurate? You could also use the built-in one in the vehicle.

For checking the voltage by reading the information built-in, there are three ways to do it.

First way applies to a regular W205 C 300, for example, you can go to DYNAMIC SELECT and under Vehicle data there will be a battery voltage screen.

Our cars on the other hand, has that replaced by the transmission fluid temperature. So you need to try the second way, which is to call up the workshop menu (same menu that allows access to service interval/reminder reset and rear brake pad change. For our cars, to enter the workshop menu, you need to be on the TRIP screen (showing the odometer etc.) and in position 1 (key position one if using the key, otherwise keyless start button foot off brake and simply press once, it won't work in accessory mode which is the double press) hold the phone button and then OK.

Should be pretty straightforward but if you are stuck, no worries, I will link you a video. Follow the steps up to the 0:34 second mark, and do not scroll down, enter Vehicle Data instead, press OK when Vehicle Data is hi-lighted, not ASSYST PLUS, you will see UB and IB. I recommend staying in that screen and take out your phone and start recording, one hand holding the phone the other starting the engine and watch the voltage and amperage change, let me know the results if you want or share the video, if you want and forum members who chimes in can determine if thebattery is charging too quick or too slow. The amperage will be pretty high if the battery was discharged a lot, if that is the case it could mean there is abnormal drain overnight or the vehicle has been sitting for more than a few weeks or old/weak battery. Hopefully it isn't the case for you.

If there are any issues with the new battery (like not charging right or charged enough), I recommend trickle charging it to full in case that solves the problem, again not sure when the new battery was manufactured, it might had been discharged too much before you installed in the vehicle and the vehicle haven't charged it high enough. Is eco start/stop (as annoying it is) working or not? This "feature" working could mean the battery is healthy and/or the charge level is correct It doesn't guarantee it but a very good start at least.

One thing to note is make sure you are on the TRIP screen and with engine off otherwise it wouldn't respond to you. Do this and compare the voltage to the meter (is it accurate?), do the same after starting the engine and do the same once again when the alternator stopped charging the battery (the workshop menu hides itself after the vehicle is locked and parked for a few minutes or so, so don't worry about not having access to it after starting the engine again and not able to call up the workshop menu again because to enable it, you need to have the engine off)
Here is a video showing you how to do it (just remember to not go to ASSYST PLUS unless you need to reset the service interval): www.youtube.com/watch?v=ngXQSBzGxqc

Last but not least, third way is to read the battery voltage using the scanner.

Good job doing a full health scan of the vehicle with the scanner, glad everything checks out and everything is healthy.

The aux battery is really just a capacitor on W205, they are cheap to replace and fairly easy to replace (other than perhaps working some back muscles because it is below the front passenger side where the glove box is and close to the activated charcoal cabin air filter, if I recalled correctly)

Do you still have a record of what the values (sitting overnight + fully charged + shortly after cranking) of the old battery as a comparison to the new battery?

You're very welcome. Happy to help. Feel free to ask any questions, more than happy to assist and I will answer if I can.

AMGCurious_702

That YouTube video was quite helpful.

Here’s what the battery tested at before starting the car. Engine however was already warm as I went to cars and coffee followed by the supermarket. However, it reads the same as the tester I bought



Here is how the battery tested after starting the car

forgot to do the third battery test after I drove the car around the block, so I went back and started it up and then turned the car off and this is how the battery tested after shutting it off seen below



I should let you know an attempt was made to locate the mfg date sticker on the battery but I don’t know where they put it.

As for the old battery, I didn’t know the car could test the battery itself at the time, my tester read 12.2 V on the old battery. But I figured it was on its way out due to its age so me being proactive. I replaced it. I still have not had a chance to check any fuses yet.

it’s worth noting I met an MB techinician at cars and coffee today and he said my H6 battery is too small for the car. I just bought what Interstate told me was the battery I needed. It seemed to be about the same size as the old battery (which was an OEM MB battery) but that I should be ok. He also noted my positive terminal was a bit loose so I’m going to tighten that up also.

just curious what is the IB? I’m assuming the A stands for “Amps”? As I drove the car around the block the IB number was ALL over the place

TwoC400s

I'm going to break with consensus here for a second, because looking at the data presented above, I think the charging/starting system is healthy.

Also, I too had a long start issue (you can find my post if you check my profile posts), and it turned out to be something completely unrelated to the engine starter or battery.

The first clue was when I pulled my plugs and had one single black fouled plug.
I changed the plug. No difference.
I changed the coil. No difference.

And then I got creative. I asked myself, "What would cause cylinder fouling?" The answer seemed obvious, too much fuel.

I changed the injector. No difference. I was stumped.

More research ensued which led me to believe it could be the VVTi sprocket on that cylinder head. It is typically the intake sprocket that fails.

That fixed it.
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W205C43PFL

Sorry for the late reply, been busy today I will read your post and try to respond by tonight if not tomorrow morning. Sorry again.

W205C43PFL

Thanks for chiming in with your experience glad to hear it fixed it for you. I will get back to OP tonight or latest tomorrow morning, thanks again for chiming in.

W205C43PFL

OP, I just went over your reply and read all the information you posted and I do apologize about the delay in the reply. I do have to agree with forum member TwoC400s that both starter and alternator and related components are working as designed.

Forum member TwoC400s suggested checking the VVT sprocket, I agree that is a good step to try. As the M276 (used in many MBs, have an infamous issue which is a startup rattle and it mainly happens when warm on quite a bit of units. The cause? Camshaft adjuster failure.

Otherwise M276 engines (3.5 NA or the 3.0T of which are one of the most reliable engines MB created.

I sincerely apologize I have nothing else to add (at least right now) and I wish you all the best in figuring it out hopefully forum member TwoC400s' solution is what you needed, if I do have a suggestion to try something I will for sure post it, until then, I am sorry for the disappointment that this response brought. I wish I was able to be more helpful.

Here is more on our engine: https://mbworld.org/forums/c450-c43-...ispreloading=1
Here is the tech paper courtesy of another forum member: https://mbworld.org/forums/c450-c43-...ml#post7722557

Forum member TwoC400s, do you mind posting the procedure for OP to inspect the sprocket and also the steps on how to change it including the part numbers, the tools, etc. if you don't mind? Thank you!

OP, best of luck with this issue! Sorry again I wasn't able to help out.

W205C43PFL

So turns out I do have something to add. Check the engine oil level using the method shown in the owner's manual. I just recalled someone having long cranking issue although it was a 2016 C 450 but same engine as our cars and for some reason (not sure it was a coincidence or not) their oil was on the lower side and pressure build up timing was affected.

Yes it doesn't sound related and I was surprised too, wish I can find the thread again but doesn't hurt to check and when did you last did your oil change? How many months or miles ago?

Other than that, check the sprockets forum member TwoC400s mentioned and recommended.

W205C43PFL

OP, any chance you got to check the engine oil yet, is it the correct level? What oil spec, viscosity and brand was used and when was oil last changed? In case you haven't, the proper way to do it on these cars is pull the dipstick out and wipe then insert and slowly pull out again, don't worry if it was dry at first pull as that was due to the airtight seal. Of course there are the basics like check the level at a level surface, engine switched off at least 5 minutes at normal operating temperature. If the engine wasn't at normal operating temperature leave the car switched off for 30 minutes, that sort of thing I think you already know already but I want to make sure so you get an accurate reading.

nishalp

Just my inputs. I agree it’s not charging or battery. Reason is you said if you prime the fuel system is works fine. I am not sure how you did that but usually that means you have pressurized the fuel system. Since it starts right away, battery is unlikely. Once you drive the car two things happen. The fuel system is pressurized and engine is warm. So restarts are easier. When you let it sit, engine gets cold and fuel system depressurizes usually. When you turn on the ignition after sitting it needs to pressurized it again and could be taking time. Some quick cheap changes and things that should be done is fuel filter. If dirty or clogged it will slow the pressurization. I am not an expert in these modern cars but I think this part should be the same. Not sure what others think. Also when last did you change the fuel filter?

AMGCurious_702

Thanks for all your help. Don’t apologize if you’re not able to. It’s all good.

I’ve been driving the car daily to/from work the last several weeks. Yesterday and the day before, car cranked normally with a cold engine. Today it did the long crank again.

I’ll check the oil level tomorrow (yes I do know how to do this haha) and will make add more oil if needed.

It’s also worth noting, after a rather spirited commute home from work in Sport+ Mode (had a bad day and wanted to get home quick) I smelled fuel, I kinda sniffed around and got a strong whiff of fuel near the rear passenger tire. Considering the long cranks, it’s leading me to believe this is fuel system related in one way or another. I’ve got a lot going on between work and personal life but I found a good Indy shop who’d be happy to take a look for me