Problems starting engine

lordluvitt

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Hello all,

My 1998 C180 estate (W202) has developed a fault. I've not been using the car regularly lately (half a dozen or so journeys in the last month) and in the last couple of days I've had trouble starting the engine.

When I turn the keys, the lights come on on the dash as normal but the engine does not start. There is an initial attempt to turn over that lasts about one second but it does not fire up. I try starting it several times but with no joy. I recharged the battery and then the engine fired up straight away. This was two days ago. Problem solved I thought. But then today, I tried starting the engine and the same problem occurred. The battery is now on charge again before I can test again later. When I used the car two days ago, I noticed a problem with using the electric windows. They would wind down without any fault but would not automatically wind up. To get them up, I had to continually press the button several times for them to occassionally wind up about 5mm at a time, but not every time the button was pressed. This problem was noted on all four windows.

Just wondering whether the battery has had it and needs replacing or whether there could be a fault with the window electrical system that could be affecting the starting (or even shorting out and causing a battery leak)? However, the battery is not completely flat - the lights and radio work okay but not the engine.

Anybody with a similar experience or that can point me in the right direction for a cure?

Thanks.

Dylan.
 

Alex Crow

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hi dylan. you describe flat battery symptoms, possibly an old battery, possibly poor charging or maybe excessive quiescent current draw. check the age of your battery first, if it is an MB batt then there is a date stamp on one of the battery terminals in week/year format.

your windows have automatic and manual functions - the switches have two stages (two `clicks` in each direction) first is manual, second auto. wind them all down, then press each switch gently till the window starts to move, then keep it pressed for a couple of seconds after it reaches the top. repeat for the other windows. your flat/disconnected battery has caused this as the DCMs memories of basic position has been lost.
 
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lordluvitt

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Thank you Alexander. You are spot on about the battery. Having had it on charge for the best part of the day, I ran a voltmeter across the terminals and it read 14.74V with the charger connected. With the charger removed, I immediately tested it again and the reading was 13.00V. The reading then dropped by .01V every 30 seconds or so and after about 45 minutes, the reading was 12.63V. These tests were done with the battery on the bench so it was clearly the battery itself that was not holding the charge and not the result of a drain from a circuit. The label on the battery suggested that it was 8 years old - definately time for a replacement I think.

I'm intrigued by the functions of the window switch. In two and half years I have never noticed that they have two stages. I will play with these when the new battery is fitted and hopefully reset the memory for the basic position. Thanks for the advice.
 

Alex Crow

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that 12.63v is fine and dandy, not indicative of a problem. however if it is 8yrs old it has done very well indeed - when you reconnect the batt, have the volt meter connected too. watch the voltage when you start the car and see how much it dips, then leave the headlights on for 10 mins and do it again. if it drops to 9.5v or lower then it`s definitely u/s, but at 8yrs old it needs replacing whatever the result. with the engine running check the charge rate, should be at or over 13v at idle with lights, rear screen heater and blower motor on.
 

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Just adding that when the battery is flat, you will have to re set the windows and roof by holding the switch in the closed mode for a few seconds with the key turned to 2.

You could have a battery drain fault.. you can either test with an ammeter or charge the battery up while disconnected, then join up after a couple of days, if it starts that way round,then a short on the car
 


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