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Discussion Starter #1
Left home on Oct 24 to go to dealer to pick up some trunk lid parts. Battery Light was on, turned off a couple of times, but mostly stayed on (18-mile one-way trip to dealer). Ordered voltage regulator. Drove home, and engine quit half-way home. Started engine once, then after 5 minutes the radio quit, transmission stuck in 3rd gear I think, and power steering assist was reduced by 20%. Then engine quit for final time. I called for tow truck. I was able to re-start the engine, and "maybe" I could have made it part-way home, because battery was able to collect enough current (as batteries tend to do), but I figured the tow truck could find me easier if I stayed in one place. Tow truck finally arrived and towed car home.

Yesterday I used daughter's truck to pick up the regulator. Today I changed oil in another vehicle and read how to change the regulator. I replaced one in my W123 about 12 years ago -- similar steps. Tomorrow I'll replace it.

I'll let you know how it went. There are 2 wires to disconnect, and I'll insulate them ... don't want to disconnect battery and have to go through the "windows-reset" procedure. I plan on removing most of the air cleaner parts to make room.

BRgds,

Dave H.
 

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Hi, if I were you, I would disconnect the battery before any servicing or fixing on the electrical circuit or any electrical component. Keep one door and the trunk (slightly) opened during intervention. Window reset is nothing compared to a huge mistake on the wires that would damage computers or relays, even if you're confident enough in your insulation step.

Tell us...

Jean-Louis
 

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Hi, if I were you, I would disconnect the battery before any servicing or fixing on the electrical circuit or any electrical component.

Jean-Louis
Jean-Louis is a very wise man. What he says is especially true for the alternator, where you have live +12V all the time. Unfused!



The job itself is simple and self-explanatory, but you touch the wire and the battery is connected, you will be in for a huge (unpleasant surprise).

If I were you, I'd remove the alternator and do the job on the bench, although on the S320 there might be enough room in the engine bay to do it in situ.

Good luck and be safe, please!
Steve
 

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I was unable to do the job without removal of the alternator..after much trying just could not get the back cover off in situ. A breeze once the alternator is removed. BTW no reason to have a original 18 year old regulator for a new unit of less than $20 why risk a break down.

Seth
 

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I dont know whether this applies to the 6 cylinder, but I was able to change the VR in-situ on a M119 car. The cover has to be rotated and flexed quite a bit to come off, but it went off and back on without breaking. Sadly, it took a new alternator anyway to cure the problem.

Mike in ABQ
 

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Today is Monday, Nov 20. Well, I know I started this thread in late October - voltage regulator from dealership - price not bad). Had to work around weather and other stuff. Replaced regulator around 14 Nov. One brush was half as long as the other. New brushes definitely longer than old ones, but not as short as I'd expected...so, maybe the alternator is the culprit. With S320 engine, it is still hard to remove black plastic cover, but should be doable....3 tabs have to be simultaneously pressed. That's the hard part. I called dealership parts to see if the cover can be ordered. They said yes, although it'll be 8 business days from Deutschland. So, I pryed cover off, and it cracked by on tab area. Ordered cover part.

I DID remove battery cables, mostly due to recommendations from everyone here. Put everything back together. There was just enough juice left to start the engine. The bad news is, the battery light stayed on, and a few other instrument panel lights came on.

So...my guess now is that the alternator needs replacing. Should be easy. Some 140's I saw on a youtube video, said one of the mounting bolts (there are 2?) has a bushing/sleeve that is troublesome to re-install, IF it gets removed. I'll let you know.

BRgds,

Dave H.
 

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My point was...

I am aware of the VR cost. When the OP stated he was using a $20 part, it caught my attention. There would be no reason to skimp on money for the part. Correct, constant voltage is to important with these cars, as you well know.

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I stand corrected. I did not bother to look up the current price $28 but my point was that a quality VR is NOT expensive.

Seth
 

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...if changing the alternator you will need an impact gun (the easiest way) to remove and replace the alternator pulley. No the replacement alternator does not come with the pulley.

One point I did find interesting though maybe some of you could comment on...seems it is suggested by MB that the pulley be replaced if >60Kmiles

Seth
 

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Discussion Starter #13
The SOLUTION was to install a new/reman alternator...got it from Autohausaz. After installation, the battery light no longer stayed on. There are no bushings with the bolts. Fairly easy to install from above on a 320, once the air cleaner parts are removed. I also removed the metal bracket that is between the headlights. I removed the coolant hose from the coolant tank, plugged both the openings, swivelled the hose to the right, including the little T connector and the 2 hoses connected to it. This gave more room to install the bottom bolt. I installed the top bolt first. I was going to install the bottom one first, but the alternator was too heavy to hold with the left hand in the correct place long enough. I thought if I put the top bolt in first, the alternator would be in the way of putting the bottom bolt it, but it turned out to be ok.

For the tensioner I used a ratchet, and a pipe over it to get better leverage, and left them engaged after slipping the belt off the alternator. But then I needed another ratchet for the 2 bolts...fortunately I have 2. I used a 15mm wrench installing the bolts - seemed easier than the ratchet. After I ran out of parts and things to tighten, I figured I was done. I had charged battery to 12.9V and 96% the previous 24 hours. The Bosch instructions said "...battery must be fully charged...", otherwise it would be bad for the alternator. The battery cables must be the last things to attach.

Cheers - Dave H.
 
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