115 amp Alternator Problem - PeachParts Mercedes-Benz Forum

DrewGerhan · #1 03-18-2008, 10:06 PM

Well, after reading many posts about the 115 amp alternator that can be taken from a Saab, I decided to go down to the Pull-A-Part and get one.

I got everything installed without a hitch and even got new 4 ga. wire to replace the old stuff. Now heres the problem. When the car is running at anything above idle, the is a rhythmic flickering of my lights and blower. Could this be the voltage regulator? I took a look at it and plan on replacing it when I get a chance.

The other problem is that my headlights don't work anymore. When I first tested the alternator around the block everything worked as it should. Then I was leaving my girlfriend's house Sunday night and the headlights turned on normally, but then after a minute, they went out. Then I tried my brights and they worked so I drove with those on, but then they turned off. I pulled over to check the fuses and they are all intact. I recently replaced all my fuses too. I got home using the fog lights which work just fine. Although they flicker too along with the dash lights.

Any ideas?

babymog · #2 03-18-2008, 10:12 PM

Check the voltage, it sounds like it is too high and burning out lights. Did you connect the second wire correctly?

DrewGerhan · #3 03-18-2008, 10:19 PM

I meant to do that when I got it installed but my multimeter was dead. I attached the wires exactly how they were on the 55 amp. Replaced the two small ones that are run together with a 4 ga one and the thin blue wire went to the only other terminal on the alternator.

babymog · #4 03-18-2008, 10:25 PM

Should be correct, but it sounds like you're seriously overcharging. It will do damage, probably should start by checing voltage, might have to take the alt in for a quick test at autozone et al, probably the regulator.

DrewGerhan · #5 03-18-2008, 10:30 PM

Yeah, I was going to take it up there tomorrow. What causes/fixes over charging?

babymog · #6 03-18-2008, 10:46 PM

Regulator, internal. No external adjustment available.

pawoSD · #7 03-19-2008, 12:17 AM

I think if I do pull a used AL129x from the yard, I will replace the voltage regulator before I use it. New ones (reman) from a local McParts are only $150ish though....and thats not that bad.

mobetta · #8 03-19-2008, 03:05 AM

are they interchangable?? w/ the old one to the new?

DrewGerhan · #9 03-19-2008, 09:37 PM

Well tonight I checked the voltage across the battery at idle. The magic number topped out at 16.4V.....AT IDLE! After this I promptly ordered a new voltage regulator. Should I drive my 500SE until the new regulator comes?

bustedbenz · #10 03-19-2008, 10:07 PM

Quote:

Originally Posted by YoungBenz

Well tonight I checked the voltage across the battery at idle. The magic number topped out at 16.4V.....AT IDLE! After this I promptly ordered a new voltage regulator. Should I drive my 500SE until the new regulator comes?

I wouldn't. You risk battery damage.

Oh, wait. Confused. Whichever car does NOT have the 16.4v alternator. That's the one to drive.

babymog · #11 03-19-2008, 10:08 PM

Yes, definately.

DrewGerhan · #12 03-19-2008, 10:24 PM

Yeah thats what I'm thinking. Could I have done any other damage to the car other than blowing out my headlights? All other electronics work fine, even my stereo with two 1600w subs. Which is the reason that I swapped alternators in the first place.

vstech · #13 03-19-2008, 10:33 PM

with that voltage at idle, you were probly putting out over 18 at speed, major destruction to the battery and any other parts not designed for the extra. could have over speeded the blower, the battery probly absorbed the damage on a short term though.

babymog · #14 03-20-2008, 08:57 AM

Check light bulbs, brake lights etc. that might have operated when it was running. Other than that, electronics, if it functions it's probably okay the better electronics are protected.