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Matt
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 21725
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Mercedes A140. Reg 2000. My wife's car is having starting

Customer Question

Mercedes A140. Reg 2000.
My wife's car is having starting problems. It will be OK for a few weeks then the starting problem will occur. She has now lost all confidence in using it.
When turning the ignition key to start the car there is a clicking noise & at first I thought the battery was flat or no good,whowever the battery is a new one.
The car has just done 43k miles and is in pristine condition & my wife really loves it.
Can you please HELP.!
Submitted: 10 months ago.
Category: Mercedes
Expert:  Shantal-Mod replied 10 months ago.
Hello,
I'm Shantal and I'm a moderator for this topic.
I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.
I was checking to see if you had already found your answer or if you still need assistance from one of the Professionals.
Please let me know if you wish to continue waiting or if you would like for us to close your question?
Thank you,
Shantal
Customer: replied 10 months ago.
Still need assistance,so please keep looking. I was very upset & disappointed with your original reply.
How can you possibly tell me that you could not find anyone to answer my question with regards ***** *****
wife's car problems,but you would give me a 10% discount on any other problems that I requested.
When I pay up front for a service,I expect your company to honour it's promises as advertised.
Expert:  Matt replied 10 months ago.

Hello

Apologies for the wait

I'd say that you may have a battery drain that's flattening the battery overnight so

I'd first check the easy things like is the boot light or any other interior light staying on then check that the main battery connections are tight and in good condition also check the earth strap to the engine / gearbox.Next I'd check the current drain aspect, the best way to find what circuit is causing the excessive currant drain is to fit a current sensing multimeter in series with the positive battery lead on the car and the battery, or use a current clamp meter on the battery positive cable.

A typical current drain with everything off and un-alarmed should be around 0.05Amp and if its higher than this remove a fuse and re-measure, if measurement doesn't change then replace the fuse and remove the next.

Once you've isolated the circuit with the excessive drain check the wiring connections and plugs to components and the wiring harness that runs by the engine bay fuse box - the wiring harness chaffs / rubs through and gets damaged - but its not always easy to see so be careful when checking..

Also check that the alternator is actually charging the battery in the car by taking a battery voltage reading with the engine off then another with the engine running. The 2nd reading should be higher than the 1st and climbing steadily. And also check that the alternator is secure to the engine as this provides the ground for the charging circuit and make sure that the engine / gearbox earth strap is secure and the contacts are clean and bright.

if the alternator appears not to be working - take it to a electrical specialist and ask them to test it as sometimes you can replace just the diode pack and this will repair the alternator without requiring replacement

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