R170 (3.2 SLK) Alternator question....
07-03-2006, 03:36 PM
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R170 (3.2 SLK) Alternator question....
I was driving home today and the BAS and ESP lights came up and I noticed the car running a bit rough.
I pulled over and turned off the engine and then tried starting again to see if that cleared the lights but she wouldn't start, just kept clicking, like a flat battery.
I left it 30 mins and re started and limped home slowly.
Putting a meter on the battery (with the engine off) only showed 11.2v
When I start her she still shows less than 12v and when you rev her then she actaully drops a little to 10.8v ?
I am guessing the alternator has given up but before I buy one anything else to suggest ? - Wires off ? - Fuses ? - Special Relays ?
Have they not got charging lights like in the old days
Any advice anyone ?
I pulled over and turned off the engine and then tried starting again to see if that cleared the lights but she wouldn't start, just kept clicking, like a flat battery.
I left it 30 mins and re started and limped home slowly.
Putting a meter on the battery (with the engine off) only showed 11.2v
When I start her she still shows less than 12v and when you rev her then she actaully drops a little to 10.8v ?
I am guessing the alternator has given up but before I buy one anything else to suggest ? - Wires off ? - Fuses ? - Special Relays ?
Have they not got charging lights like in the old days
Any advice anyone ?
07-03-2006, 05:04 PM
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03 E320 -wife's car now; 07 Porsche Boxster S - my toy
Justin,
Did you try charging the battery to see if it would come up to, and hold at 12.6volts? If you've done this, and started the car, what is the voltage with the car running (alternator running)? It should be at least 13.5 volts. Is there any shop near you that has a Midtronics battery tester, as these can also test the charging circuit?
When you rev the engine, and the voltage at the battery drops to around 10.8 (or anything less than the 12.6) this is an indication that the battery is not charging.
Is your model included in the alternator recall because of bad regulators? This is particular to the W211 family (E-class).
Regards,
paul...
Did you try charging the battery to see if it would come up to, and hold at 12.6volts? If you've done this, and started the car, what is the voltage with the car running (alternator running)? It should be at least 13.5 volts. Is there any shop near you that has a Midtronics battery tester, as these can also test the charging circuit?
When you rev the engine, and the voltage at the battery drops to around 10.8 (or anything less than the 12.6) this is an indication that the battery is not charging.
Is your model included in the alternator recall because of bad regulators? This is particular to the W211 family (E-class).
Regards,
paul...
07-03-2006, 05:53 PM
#3
MBWorld Fanatic!
With Mercedes/Bosch systems it's probably 95% likely the battery and 5% likely the alternator.
If it is an alternator problem, it's probably the regulator, which may be separately replaceable on your model. Lot less expensive if it is.
Your owners manual will detail where the charging light is. They don't illuminate when it's a bad battery.
If it is an alternator problem, it's probably the regulator, which may be separately replaceable on your model. Lot less expensive if it is.
Your owners manual will detail where the charging light is. They don't illuminate when it's a bad battery.
07-04-2006, 07:42 AM
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05 ML350, 85 300D
There is a little box in front of the battery that is a fuse unit for the alternator( actually, its a safety shutoff if the SRS deploys, but it acts like a fuse)- check the voltage on the alternator side of it- if it's blown, it will be way high- like 18 V- the alternator is trying to charge the battery, and it can't get there... Very common on 170 cars
