DIY- E55 Alternator replacment
Thread Starter
Junior Member
Joined: Dec 2008
Posts: 44
Likes: 0
From: Castle Rock, CO
E55 Wagon-Audi-Land Rover
DIY- E55 Alternator replacment
My alternator went bad yesterday, thought it was going to be the regulator but once I dismantled the regulator I noticed the diode pack had overheated and melted in areas. See attached picture. I read about others smelling a slight plastic/electrical smell and voltage dropping causing the battery errors on dash to pop up. Based on this it made sense to replace the alternator. After a few hrs or looking through the process I managed to unbolt and remove the alternator with only removing the fan housing and a few hose brackets. Bit tricky getting it out but managed to manipulate the hoses with no real problems. ordered a replacement alternator that arrives tomorrow and will document the install with pics including fan housing etc
On the other hand in leveraging the alternator from its mount I broke the plastic idler pulley. The one that has the double pulley just above the alternator .... was not a happy chappy. Anyone know where to get a good replacement? is there an aftermarket upgrade that is better quality than the OEM? I need to order this asap as we are going on a road trip with the family Friday morning and need to get a replacement fast.
Tried to load my pictures of the burnt alternator but would not load, I'll try to load these again later tonight.
On the other hand in leveraging the alternator from its mount I broke the plastic idler pulley. The one that has the double pulley just above the alternator .... was not a happy chappy. Anyone know where to get a good replacement? is there an aftermarket upgrade that is better quality than the OEM? I need to order this asap as we are going on a road trip with the family Friday morning and need to get a replacement fast.
Tried to load my pictures of the burnt alternator but would not load, I'll try to load these again later tonight.
Last edited by rsracing1; Jun 11, 2013 at 09:35 PM.
Thread Starter
Junior Member
Joined: Dec 2008
Posts: 44
Likes: 0
From: Castle Rock, CO
E55 Wagon-Audi-Land Rover
Alternator is scheduled for delivery this morning and will try to document with pictures the install on how I get it in with out removing/draining cooling system
Junior Member
Joined: Oct 2014
Posts: 60
Likes: 2
From: SOCAL
SL55, SL500, SLK320, ML320, CLK 430
alternator diode pack melt down
Anyone know what may cause this?? About a month ago I was driving and smelled an electrical fire I pulled over and it was my alternator. I had my sl55 towed home and replaced the alternator with a new one. Well just last week the same thing happened, dash lights, red battery /altermayor loss of brake power etc. I replaced the alternator again and I'm worried it may happen again. The car drives great just want to take preventive measures, can grounding issues cause this or perhaps a low battery overworking the alternator???
MBWorld Fanatic!
Joined: Nov 2007
Posts: 3,681
Likes: 39
From: San Diego
E55
Anyone know what may cause this?? About a month ago I was driving and smelled an electrical fire I pulled over and it was my alternator. I had my sl55 towed home and replaced the alternator with a new one. Well just last week the same thing happened, dash lights, red battery /altermayor loss of brake power etc. I replaced the alternator again and I'm worried it may happen again. The car drives great just want to take preventive measures, can grounding issues cause this or perhaps a low battery overworking the alternator???
What went out on your alternator? Was it the voltage regular or something internal?
Member
Joined: Jan 2015
Posts: 88
Likes: 1
2006 AMG E55
Thanks for the DIY write up. I had to tackle this on Saturday myself. I replaced the voltage regulator first but my car under full load (100% WOT) would lose voltage and give me the red battery warning.
It was a major pain and i did end up pulling the radiator hose to clear the alternator out.
One working is be mindful of the radiator support bracket. Under the bracket is the wire to open the hood and those clips need to be removed or you can run the wire off track and then the hood does not open.
. Also while you in there get a new belt and tensioner if it's within you budget. I wish I did because now I need to go back in there to replace those items
It was a major pain and i did end up pulling the radiator hose to clear the alternator out.
One working is be mindful of the radiator support bracket. Under the bracket is the wire to open the hood and those clips need to be removed or you can run the wire off track and then the hood does not open.
. Also while you in there get a new belt and tensioner if it's within you budget. I wish I did because now I need to go back in there to replace those items
