'88 300TE: Bad alternator? Upgrade?
 

Wanted to get some opinions from the Forum. Upon starting the TE yesterday, all of the warning lights on the dash came on, dimly. Having had a bad alternator before, I immediately checked the voltage at the battery and found 11.2 volts. I shut the car off and tested it at the battery again, which registered 12.3 volts. Clearly the alternator's not doing much, if anything. I then pulled the plug off of the alternator, and found it to be a bit corroded. I gave it a quick cleaning, coated it in electrically-conductive grease, then re-inserted it. Fired the car up, and I saw 13+ volts at the battery.

However, when I turned on a few accessories (A/C, lights) the voltage dropped (again, measured at the battery) to about 12 volts, at idle. Shouldn't the alternator still be putting out some power at this point? Plus, I think I hear some noise coming from the alternator, and a new smell is coming up from under he hood.

FWIW the current alternator is 4 yrs/50k miles old, and is a Bosch reman. Presuming it's giving me a warning before it dies outright, I think I'm going to replace it. I'd like recomendations as to a higher-output unit (not the huge 143 amp unit though) that'll bolt right up - perhaps from a ;94-'95 E320? Any ideas?

Thanks in advance, guys

The 1990 & later 300E's use a 80A alternator(AL66X bosch) that is a direct fit requiring only a small wiring harness. This is an up-grade that will make a big difference in the summer OR if you have an aftermarket stereo.

Thanks Doc!
 

I followed up my earlier post with a call to my local MBZ retailer. Turns out that there's an even bigger alternator (90 amp) that's supposed to be a bolt-on: MBZ P/N 009 154 02 02. Should also require the same wiring modification, specifically soldering the early-design 2 smaller (+) wires together to mate to a single ring terminal. Otherwise the bigger alternator seemed to have all the same design parameters as the 80 amp. We'll see when it gets here tomorrow.

FWIW there's also an even bigger alternator, 110 amp, that should bolt up (it's specified for a '95 E320) but it does also specify a different V belt be utilized. Since the M103 and M104 engines used different V-belts, and there was only a P/N for the alternate belt on the M104 application, I decided to settle for the 90 amp.

Now, can anyone give me advice on how to remove the V-belt? The bolt that holds the tensioner in place looks pretty tough to get to - any tricks?

I'll advise as to how the install goes.:)

Whichever alt you use the best way to wire it is to use the later harness 124 543 45 26. The difference between the early alt and the later in the hook-up is the output terminals screw on the hi outout alternators.

Unless you can aquire 8mm ID eye terminals of proper stature and solder them in you will be using up connectors with the high output.

Re: Thanks Doc!
 

Somewhat covered in...

http://www.peachparts.com/shopforum/tech-help/65674-86-300e-indicator-lights-alternator-prob.html?highlight=tensioner

I"m not sure how the hydraulic pump in a TE complicates things.

BTW, it's not a V-belt if it has multiple grooves.

Sixto
91 300SE
87 300SDL
83 300SD

It's tough to get to, but not impossible.

Now, near as I can tell it's not 17mm; likely is a 19-need to go pick up a deep 19mm to get in there.

Thanks again!

It was 19mm-easier to get to from under the car.

Installation was pretty straightforward, other than having to swap the pulley over from the old unit to the new one (which uses an internal fan, rather than the external separate deal on the old unit)-needed air tools for that.

I soldered high grade ring terminals on the end of the old harness wires-looks great, now we'll see if it holds up (Thanks Steve).
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