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1994 Mercedes-Benz S320 SWB
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93 Posts
Discussion Starter #1 (Edited)
I just had my head gasket done for the second time on my 1994 S320.. The engine works just as it should after the job but now I am having electrical problems. Heres whats happening...

After driving for acouple minutes the Battery, Check Engine, ABS, and SRS indicator lights will start blinking, the head lamps and gauge cluster lights illuminate very brightly then go back to normal. The radio also shuts off and On.

Once it starts happening it wont stop until I come to a stop and put the car in park.

The engine runs fine while all this happens but there is a serious electrical problem going on, Anyone experienced this?
 

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1994 Mercedes-Benz S320 SWB
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93 Posts
Discussion Starter #2
bump


anyone? i have videos of the engine and the gauge cluster if anyone would be interested in seeing them.
 

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1986 560SEL, 1986 560SEL, 1992 500SEL, 1999 S500
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473 Posts
You may have a deffective voltage regulator or wiring problems in the alternator circuit. I would check all cabling coming from the alternator for proper connections, especially grounds as they may have been removed during the head removal. Also I would check the voltage at the nattery with a meter when this problem occurs.
 

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1994 Mercedes-Benz S320 SWB
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93 Posts
Discussion Starter #4
I just got a volt meter and check the voltage while the car was running and the problem was happening... 17.4 Volts!

With car off and the battery voltage was 12.4


Could my voltage regulator in the alternator went bad and the high voltage throwing everything out of wack?
 

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2011 GLK,2007 S550,2003 S55,2008 CLK,2009 C300,1996 E300,2005 E320,2002 E3
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1,355 Posts
yeah you have something really wrong...you shouldnt be anywhere near 17 volts...mid 13's maybe
 

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1986 560SEL, 1986 560SEL, 1992 500SEL, 1999 S500
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473 Posts
Again, check all wiring from the alternator and any near the head, looking for anything disconnected--like ground straps to the engine or head. This is too coincidental and points to something being disturbed during the recent work.
 

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1994 Mercedes-Benz S320 SWB
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93 Posts
Discussion Starter #7 (Edited)
I assumed it was the mechanic at first and I will double check all the ground and connections but before the job was done my front cover would leak oil onto my alternator, 2 have gone out that way before this head gasket job so that also seems possible too but Im going look into it more.. thanks
 

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1994 Mercedes-Benz S320 SWB
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93 Posts
Discussion Starter #8
A faulty wire harness could not make the voltage spike to 17 volts right? it has to be the alternator regulator failing and sending too much voltage to the electronics and throwing them out of wack?

Do you guys think I could be right?
 

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1994 Mercedes-Benz S320 SWB
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93 Posts
Discussion Starter #9
Bad alternator or voltage regulator

I took the serpetine belt off to troubleshoot the problem.. Once the belt was off and the alternator wasnt charging all the problems dissapeared and the idle was perfect. No dash lights and everything was good so I am happy!

I got a warranty on the alternator so im getting my replacement on the 29th.
 

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1997 S600 (sold)
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4,660 Posts
Check your battery just to be sure. An overcharging battery can cause the battery acid to "boil" over. It's not really boiling, just producing H2 gas which can cause the viscous battery acid to spew out the vent and into the battery tray area. That acid can wreak havoc on the metal. If there is evidence of "boiling over," neutralize with sodium bicarbonate solution (baking soda) and check the battery cells for electrolyte level and add distilled water as necessary.

Brett
 

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1994 Mercedes-Benz S320 SWB
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Discussion Starter #11
I checked the battery before the alternator.. Its 12.4 Volts and starts the car up everytime..

Its a very nice mercedes battery and its the kind you cant add water too. I checked it and nothing leaked out and I also was listening to it for boiling while the alternator was charging at 17 Volts for just a minute and nothing seemed to get damaged so the battery is good.
 
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