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Just bought an 2000 e430 and it didn’t turn over from what the guy I was buying it from said . He had it for many years and never had any issue with turning on and off . He returned from shopping to try and start it and it just clicked . He did the normal and bought a new battery and starter to diagnose it . Also a starter and a couple of fuses but no luck . Fast forward to me , I tried the exact same thing but with a platinum battery brand new . And a new non reman starter . Same results . Also cleaned main body ground harness and a couple of smaller ones in the engine bay . I get a loud thunk! Every time and if I hold it I just goes “ thunk thunk thunk ! I tried turning it over with screwdriver and it’s cranks the engine but no start . So I assume that’s fine . But why is the starter not engaging with enough force to turn it over ? I also turned the engine over completely with ease by hand . And no accessories locked up either without belt . Help guys please . Only 140,000 miles
I’m having a little trouble parsing some of your terms.
Let me know if I have this right.
1. Engine will not crank when key turned.
2. Starter and battery replaced multiple times.
3. If you use a screwdriver to bridge main 12V+ on starter to the solenoid, it cranks the engine.
4. If you put a breaker bar on lower crankshaft pulley, you can spin the engine by hand easily.
5. When key turned to start, the starter makes a “thunk” sound but does not spin engine.
Here are some questions, assuming all above correct.
1. If you do the #3 from above while a 2nd person sits in car with ignition to “run” does the car start and run?
2. Have you checked whatever relay it is that sends 12V+ to the solenoid?
If the starter can spin the engine with screwdriver to solenoid, no worries about engine being seized.
Thank you so much for the quick response ! I’m sorry I typed the starter twice . But yeah so I turn the key to on position and when I try and start i get a loud thunk ! Noise like the starter is trying to turn but just freezes up or like it’s not enough juice . I’ll go out side and send a video.. the original owner tried a starter and I tried to install one as well because it seems like the only reasonable issue with the sound it’s making .
I have not tried to jumper the starter with a screw driver while someone attempts to turn it over . I only left it in on position and I went under and tried turning it to see what happens . Also I do not recall checking which relay fuels the starter because I assumed he already replaced every fuse from what he was telling me . from what I understand ,he has quite a few and didn’t want to put anymore money into this one that have now . I believe he was taking it to the dealer and got tired of forking out money . I’m a novice wrencher but willing to learn from anybody . Not stubborn and will do whatever is necessary to get it running because I always wanted a v8 Mercedes that fit my budget .
Ok, thank you. Have you checked the ground straps? As in corrosion at each end. Should be one (or more) to chassis and the engine.
In the video is the screwdriver being used to make the starter go or is person inside car turning key each time?
Also, it sounds like the motor is turning just a little, so it isn’t just the starter gear sliding forward and not turning. It turns for a brief spin or two, it sounds like.
Last edited by MacVidMB-V8; Jun 11, 2025 at 08:35 PM.
Here’s another video from me just trying with my helper leaving it in the on position and no the first videos is how it sounds with only the key trying to turn it over with no help from me
Yes I have checked the grounds and filed them until they’re shiny . One big one from body to bell housing under car . And also power wire going from starter to body . Then three smaller ones inside engine bay . One by each fuse box and one under air box . Also another one attached to secondary air pump .
Also I’m sure you are familiar with Mercedes and hear about the k40 module ? You think that could be the culprit ? I seen it earlier today while messing around with it and it seems pretty fresh no corrosion around it : just throwing ideas out there I really don’t know ..
More likely it isn’t the key but something AFTER the key. Which leaves EIS (ignition switch) or something after. I’m not as familiar with the specifics after the key but typically the EIS & ECU agree the key is good and enable start and ignition.
You are probably going to have to get access to a diagnostic machine that can speak Mercedes.
It would be helpful if someone familiar with the stuff between key and starter chimed in. I imagine there is a relay somewhere along with ECU.
It’s the bottom left key in the picture you showed me . And yeah I think that’s my best option is to get the 38 pin one so I can talk directly to the brain . I only have an obd2 Which shows nothing . I guess I’m kind of stuck until then . I can update you guys after I purchase one . Thanks
Also yes it locks and unlocks but what is a good reader for Mercedes Benz that’s beginner friendly? I’ve surfed the web and seen the autel and carsoft for most of what I need . But the more advanced is the star system . Any help would be much appreciated!
For me and this is for me only, I have Foxwell with 38-pin. I hear Autel is also good, but I have no experience with it.
Bottom line is how comfortable you are with whatever system you go with, and how much can you afford. My Foxwell was somewhere around 200 USD (I could be wrong. Maybe it was little more higher. I bought it from Amazon). All scanner is unique to it's own and will need to get used to operating and reading it.
Just to let you know, I'm still getting to know my Foxwell scanner and I work as GSE mechanic. I mean, how often do you scan the car?
have you tried charging that battery up sounds like lack of power
is there two batteries on that car can’t remember if there’s one in the boot and a larger one in engine bay could be hidden under scuttle panel
which battery did you replace ? Front or back
Originally Posted by JoseE430
Just bought an 2000 e430 and it didn’t turn over from what the guy I was buying it from said . He had it for many years and never had any issue with turning on and off . He returned from shopping to try and start it and it just clicked . He did the normal and bought a new battery and starter to diagnose it . Also a starter and a couple of fuses but no luck . Fast forward to me , I tried the exact same thing but with a platinum battery brand new . And a new non reman starter . Same results . Also cleaned main body ground harness and a couple of smaller ones in the engine bay . I get a loud thunk! Every time and if I hold it I just goes “ thunk thunk thunk ! I tried turning it over with screwdriver and it’s cranks the engine but no start . So I assume that’s fine . But why is the starter not engaging with enough force to turn it over ? I also turned the engine over completely with ease by hand . And no accessories locked up either without belt . Help guys please . Only 140,000 miles
have you tried charging that battery up sounds like lack of power
is there two batteries on that car can’t remember if there’s one in the boot and a larger one in engine bay could be hidden under scuttle panel
which battery did you replace ? Front or back
A 2000 Mercedes-Benz E430 typically has two batteries: a main starter battery and a smaller auxiliary battery. The main battery is usually located under the hood, while the auxiliary battery can be found in the trunk or under the rear passenger seat, depending on the specific model year and configuration.
Hmm did not know there was two batteries on my model ?? I seen the one in the trunk . But I was unaware there is another one hidden . As far as scanning goes I have a pretty expensive obd2 scanner but it’s for every model . Like 300$ from local auto parts store . It’s not reading anything because I can’t get it to crank and no stored codes from what I can see . I was assuming maybe a Benz scanner could pick up more from the ecu .
On your media display in centre of dashboard I think it gives you your 12v actual reading try charging the battery up from under the hood should be a red slider slide it to get access to positive terminal and there is a brass coloured post sticking up that’s where the negative attaches
guy said he had replaced battery in trunk to me that’s the auxiliary battery later models did away with the auxiliary battery and just had the bigger battery under the hood am I correct?
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