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#1
11-10-2004, 08:29 AM
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Dang alternator acting up AGAIN????????
Dang alternator acting up AGAIN????????
I just replaced the regulator back in the spring, now its outputting 17.49 volts again.............not undercharging but OVER charging. Before I fork over more money for a new one does anyone have ideas what would cause this condition?
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Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche 
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#2
11-10-2004, 08:32 AM
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Nope- but I have been chasing that same problem in my old Ford pickup for months. Been through 3 voltage regulators, checked all the grounds......
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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)
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#3
11-10-2004, 09:18 AM
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I went through two brand new voltage regulators on my '68 F250, both the old fashioned, bulky, mechanical type. Turns out NAPA offers a "solid state" (i.e. transistorized) voltage regulator which worked and still works. You can immediately tell the difference because it is a much slimmer unit than the original.
This probably doesn't help the original question, as I don't know if your alternator is internally or externally regulated, but it seems to me that there are some poor quality mechanical regulators out there. Both of my bad units would overcharge to the tune of 17 volts or so. Part of the reason why a volt meter is so much more useful than an Ammeter in a car. Kevin
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'85 300SD
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#4
11-10-2004, 09:30 AM
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This is on my '79 300SD, internal Bosch regulator. Last time it hit 18 volts fried my tach, stereo and half my lights along with contributing to the early demise of my battery.
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche
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#5
11-10-2004, 09:48 AM
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1 Clean ground cable at body of car.
2 Clean conections at alt. 3 Replace regulator 4 Ground alt. to body. Hope this helps Bill
__________________
94 dodge cummings,86 ford 6.9,75 mbz 240d[ sold], 82 mbz 300sd,83 mbz 300sd
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#6
11-10-2004, 10:01 AM
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Quote:
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche
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#7
11-11-2004, 03:15 PM
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What do you mean??
Quote:
Thanks, Dave 80 300D
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#8
11-11-2004, 03:35 PM
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Overcharging pretty much has to be the regulator or the connections to it. If no voltage is present at the battery sensing wire, the alternator goes into maximum voltage.
If there is a short in the regulator, the alternator maxes out as well.
__________________
1984 300Sd 210k Former cars: 1984 300D 445k (!!) (Strider) Original (and not rebuilt) engine and transmission. Currently running on V80 ( 80% vegetable oil, 20% petroleum products). Actually not, taking a WVO break. 1993 300d 2.5 275k. Current 120/day commuter 1981 300SD 188k (Hans) Killed by a deer 
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#9
11-11-2004, 04:25 PM
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Not sure if it applies to MB alternators but many alternators self-destruct from the heat of overcharging. If your battery goes dead do your alternator a favor and charge your battery. If you jump the car and let the alternator charge a dead battery you are cooking your alternator. If you let your battery go dry you are cooking your alternator.
If you learn to break down an alternator and install new brushes/holder , bearings, diodes and regulator you can save bucks and stick with proven reliable components. When you buy a reman you never know where it has been. The same basic story applies to starters minus the diodes and regulator, usually bushings instead of bearings. The local alternator shop has proven to be my source of parts for starters and alternators.
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#10
11-11-2004, 05:51 PM
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Altenator problems
About 8 months ago my altenator went out and I drove down to my local "boneyard" MB Auto Shop. I bought a used altenator for my SDL for about $100. and had him put it on. All in all it cost me about $180. Well it went out the other day and I went back and got a new Bosch and installed it for about $275. after labor. So my altenator problems have been costly. So much for getting a used altenator.
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#11
11-11-2004, 08:50 PM
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Make sure the positive cable connection at the battery is good, too -- if it's loose or corroded, the alternator can go berzerk and put out 18V or more, not good for the electrical stuff!
A bad positive wire connection at the alternator or a bad alternator ground can do the same thing -- the regulator looses it's voltage reference. Peter
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1972 220D ?? miles 1988 300E 200,012 1987 300D Turbo killed 9/25/07, 275,000 miles 1985 Volvo 740 GLE Turobodiesel 218,000 1972 280 SE 4.5 165, 000 - It runs!
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#12
11-11-2004, 10:40 PM
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I will check that out tomorrow if its not raining. Spent the night replacing the lift pump only to find out the problem is still there with the power loss. And that a quart of oil or two ran out onto my cement driveway while I was changing it.........what a mess.
Not in the mood to crawl under it, besides its 10:30 pm now anyway and I get up at 6am to go to work. Ho0pe I can check that out tomorrow, I want to see something work for once....................
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche
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