51 plate c200 kompressor coupe

jungleboy

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Just when i thought nothing else could go wrong with "mary" i recieved a delightful message regarding "undervoltage, consumer defective" . I know i'm defective , i don t need the car to tell me.

This changed today to a nice red message saying "alternator/batery , visit workshop"

I already have a mortgage so i ll not be going to any workshops

I ve put a meter on the battery (which looks nice and new) and saw that after starting the voltage is steadily dropping , which makes sense , there is no warning message for the first 5 miles or so

So alternator right? Please can someone tell me you can buy new brushes for the alternator for 50p and its a common fault or the like. Just something to cheer me up

thanks in adavnce
 

television

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The battery should be around 12.5 volts with the engine off,,when running it should be around 13.8volts. the thing to do is to check the voltage when the fault comes up.

Batteries can behave in different ways. In this case is a cell partially short circuit, this could pull the running voltage down.

You do need to know the above 2 figures.

Yes reg pack are available at around 20 x 50p
 
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jungleboy

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I ve now had a bettery tester on which indicates that the battery is fine.

I ve also measured the voltage when the red message appears and i m reading 11.4V steady.

My local garage (not merc garage) hopes to get the car in and measure teh output from the alternator.

Am i right in saying that it is likely the regulator on the alternator is likely to be the problem? Is it replaceable?

Thanks very much for your promt response Malcolm
 

television

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You have no charge with that voltage,,the reg pack cost around £10 from Bosch
 

Alex Crow

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W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
I ve now had a bettery tester on which indicates that the battery is fine.

I ve also measured the voltage when the red message appears and i m reading 11.4V steady.

My local garage (not merc garage) hopes to get the car in and measure teh output from the alternator.

Am i right in saying that it is likely the regulator on the alternator is likely to be the problem? Is it replaceable?

Thanks very much for your promt response Malcolm

as mike TV says, 11.4v = no charging at all, suggesting alternator fault. but if you meant to say `reads 14.1v steady with warning on` then alternator is fine but for some reason front sam is telling instrument cluster to display message.

alternator testing is all about measuring voltages really, anything over 12.8v under any conditions is ok as this shows positive charging, but ideally you want to see 13.2v or more under all conditions. maximum allowable is somewhere around 14.6v. the biggest load on your alternator is at tickover with heater blower, rear demister and all lights on. also heated seats, electric windows and some other consumers take a whack.
 
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jungleboy

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Definately an alternator fault , i found out when trying to limp home last night and broke down.

So i guess my questions are now as follows:
Anyway to find out if the brushes or regulators at fault instead of just changing the whole thing?
How hard is it to get in and remove the alternator? A cursory glance looks like its trick and you really want the car up on a ramp...
And does anyone know of any good resources for technical drawings etc? Budget will now not even stretch to a haynes manual

Many many thanks!
 

rpe2

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His: 2018 E220 d; Hers: 2016 SMAX
Where are you located?
 
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jungleboy

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sunny edinburgh, hopefully it ll last as i m now on my motorbike
 

rpe2

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Now, a bit far to have it recovered to Olly or Colin, but the following have been recommended on the 'other' forum:


Deutsch Marque &

Edinburgh Motor Works
137 High St.
Dalkeith
 
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jungleboy

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I got it recovered to my work where it now resides with other broken cars.

Just payed to have the bushes replaced so am keen to give it a go myself. Whilst i m a dab hand with a mk 1 golf (which i now want back) not so sure aboutu getting under this complicated thing. How hard can it be to replace a regulator?
 


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