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Charging problems, need help

2K views 25 replies 9 participants last post by  plinker17722 
#1 ·
Ok guys, my 94 e320 wagon is acting weird. The other day it left my roommate stranded with a dead battery. I checked the voltage at the battery with car running and it was 11.8. Pulled the alternator out and went to Autozone to test it. It tested good.
So i did some looking around and found a blue wire that connects to the power distribution block that appeared to be chewed by a mouse or something. Fixed that. No other wires broken in the battery area.
Turned on the car and everything was fine. Voltage at battery was 13.8 to 14.
Today move the car around and noticed that the headlights were a little dim. Connected the voltmeter again at the battery and only got 12.6 and dropping slowly with car running.

What could it be? Bad intermitent alternator? Just the voltage regulator?
I did pull out the regulator and it looked good. Alternator does not look too old. But it is a made in china one. Battery is fairly new mercedes oem.
What do you guys think?


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#4 ·
I'd change all fuses to the copper ceramic fuses from Foessler from eBay. And yes, change them even if the current steel ones still look good and have continuity. Foessler fuses solved most of my electrical problems and it's a cheap and easy fix.


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#7 ·
Ok, here is an update. Took the car to have the charging system checked at autozone. Again the alternator and battery checked good.
I have been having problems with getting a good tension on the new belt. It squeals some times. Maybe I need a new tensioner. Could this be my issue? Could the belt be slipping without making noise?

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#8 · (Edited)
IF you have the older semi automatic tensioner type, you should probably replace the tensioner as the inner rubber donut probably crumbled during belt removal.

However, with a bad tensioner you will also have other issues such as A/C that won't stay on, among other issues.

If you have the later fully automatic style, then your issue lies outside the tensioner.
 
#9 ·
the new tensioner type, AFAIK, was onyl used on m104 powered W210's, not on any W124's, and changing tensioner type requires replacing the waterpump and power steering pump mount, so its non trivial.

catch-22, the old style rubber tensioner used on these engines is *expensive*.
 
#12 ·
IIRC, M104s through engine# 72236 use the older semi automatic type.

Another issue to check is to make sure the tensioner was set properly. It is a common mistake to strip out the tensioner rod. Basically, the center 19mm bolt of the tensioner gets loosened first and tensioned last. The rod is for adjusting the tensioner in according with the plastic pointer and wedge stamped on the tensioner while the center bolt is loosened.
 
#14 · (Edited)
when you release the tensioner, ideally at rest the pulley is lined up with the flats on the shaft.. when the rubber elastomer gives up the ghost, it looks like the one on the left. the one on the rigth is new and the flats aim at the pulley axle...




p.s. our 1994 E320 has engine SN 36082, so 72236 must be pretty late in MY 95
 
#13 ·
I see you live in Miami. Have you been using the A/C lately? Belt slippage with A/C on will shut down the compressor (if the slippage is at the compressor pulley - which it usually is with the A/C on)
 
#16 · (Edited)
Since you're replacing the tensioner, be sure you order a new tensioner pointer (arrow) as well as the rod assembly.

The pointer is a dealer only part, but only a few bucks. Without the pointer, you are merely guessing what the proper belt tension is prior to tightening the tensioner bolt.

Also replace the tensioner shock while you're in there. Now is as good a time as any.
 
#21 ·
As I've stated many a time before, brick 'n mortar autoparts stores carry nothing suitable for these cars other than windshield washer fluid.

On the other hand, if you're looking for Made in China crap then you've struck gold.

If it's not a domestic car, foreign cars other than Toyota and/or Nissan are not smart to use them.
 
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