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  #1  
Old 03-30-2006, 01:57 PM
neatokino's Avatar
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Alternator Upgrade? (1985 300TD wagon)

Hi all--

I just switched out my sealed beam US headlights with (used, from ebay) Cibie HCR H4 lights, 60/55w bulbs. The lights are great, illuminate much better, etc., but I noticed last night that the alternator light on my dashboard was faintly illuminated, something I certainly hadn't noticed before switching the lights. It stayed illuminated even at high revs on the freeway, and I didn't notice any dimming or brightening of the lights with acceleration.

Am I going to need to upgrade the alternator just to run these lights? The only other electrical change I've made in my car is to replace the Becker radio with an Alpine head unit.

If an alternator upgrade is advisable, can anyone recommend an easy drop in replacement for the original alternator, and suggest a reasonable amperage (75A? 80A?).

Or, is it possible that my battery is just getting old?

Or, for that matter, could this be related to the bulbs I'm using, which are old Philips that came with the lights?

I've read through various related threads about bigger alternators but couldn't quite find an answer to this particular question.

TIA
Michael ('85 300TD wagon with insanely low original 42K mileage!)

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  #2  
Old 03-30-2006, 02:09 PM
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The brushes on your Alternator may be on the way out.
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  #3  
Old 03-30-2006, 02:23 PM
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From what I have read here the alternators generally are pretty sound and don't usually need replacement. Try the voltage regulator. It's a quick easy replacement. See if that make the alt. light go out. Also might look for a bad ground.
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  #4  
Old 03-30-2006, 03:20 PM
Craig
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I agree, two 60W lights is only 10 amps which shouldn't be a problem for the stock (65 amp, I think) alternator. I would measure the voltage at the battery, then start with the voltage regulator and/or brushes.
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  #5  
Old 04-10-2006, 12:38 AM
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Alt

I would check the Alt output before changing anything. Check the Voltage with your motor running and lights on. I would think with lights on you should be getting 13.80V. With nothing on and motor running you should be getting 14V. If your reading is 12.4 etc , You need a Alt, but I would think the 65Amp should be suffiecient, I have the 55Amp Alt and it puts out 13.60 with Air con on and fan on high.
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  #6  
Old 04-10-2006, 01:00 AM
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If you do decide to upgrade - the V-8 ALT (ie 500SEL, 380SEL ect ect). will drop in without a problem and is rated at 120 - 140A. The only modification you will need to do is switching the pulley and measuring out a new set of belts. The fit is tight but it does fit.
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  #7  
Old 04-10-2006, 02:38 AM
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Quote:
Originally Posted by Breckman99
If you do decide to upgrade - the V-8 ALT (ie 500SEL, 380SEL ect ect). will drop in without a problem and is rated at 120 - 140A. The only modification you will need to do is switching the pulley and measuring out a new set of belts. The fit is tight but it does fit.

Switching the diesel belt pulley to one that the gassers used? Or putting the diesel pulley on the gasser alternator? I don't get which one you mean. When my alternator dies I am definatley upgrading to one of the more powerful ones, I think mine is a 55A one.....its been going strong 30,000 miles so far though, no idea when it was replaced beyond that, its a remanufactured.....

So overall I just want to know which pulley one would use to put the gasser alternator on the diesel. And maybe which belt size it'd need....
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  #8  
Old 04-10-2006, 10:35 AM
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Just need to replace the single pulley gasser with the dual pulley (and smaller) diesel.
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  #9  
Old 04-10-2006, 10:55 AM
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The Mean Green site also says something about alternators- perhaps they make badass alts as well as starters for our application...
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  #10  
Old 04-10-2006, 11:24 AM
1985 300SD Sady's Avatar
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Quote:
Originally Posted by Breckman99
If you do decide to upgrade - the V-8 ALT (ie 500SEL, 380SEL ect ect). will drop in without a problem and is rated at 120 - 140A. The only modification you will need to do is switching the pulley and measuring out a new set of belts. The fit is tight but it does fit.
The only ones I can find from 380SEL's 420SEL's or 560SEL's on fastlane are all 80 amp units.

I would like to upgrade this summer, what year ALT did you use,and from which model? Did you find it at a junkyard?
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  #11  
Old 04-10-2006, 12:43 PM
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Quote:
Originally Posted by Craig
I agree, two 60W lights is only 10 amps which shouldn't be a problem for the stock (65 amp, I think) alternator. I would measure the voltage at the battery, then start with the voltage regulator and/or brushes.
The brushes are part of the regulator. The regulator itself is solid state and usually doesn't fail (unless you plug the plug on wrong!) its usually the brushes that wear out and fail to make contact. A new regulator should solve it. It may just be a coincidence that the alternator became worn out (brushes that is) at the time you installed new headlights.
An AL-69X is what I used for an upgrade. You may have a single belt whereas the upgrade will use two V belts.
see this thread (used search feature!) alternator alternative (123)?
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  #12  
Old 04-10-2006, 01:00 PM
Craig
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Quote:
Originally Posted by dieseldiehard
The brushes are part of the regulator. The regulator itself is solid state and usually doesn't fail (unless you plug the plug on wrong!) its usually the brushes that wear out and fail to make contact. A new regulator should solve it. It may just be a coincidence that the alternator became worn out (brushes that is) at the time you installed new headlights.
An AL-69X is what I used for an upgrade. You may have a single belt whereas the upgrade will use two V belts.
see this thread (used search feature!) alternator alternative (123)?
I agree, what I was trying to say was that he can either replace the regulator (as I have done), or he can take it apart and just replace the brushes to save a few $$$. I've never bothered to just replace the brushes, but there is info on this forum from those who have.
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  #13  
Old 04-10-2006, 02:33 PM
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I can't remember what car it came out of but I somehow have two of them (one for backup while the other is out for rebuilding). It was a late model V8 benz... It could be 80 amps I'll have to check on that I always thought they were 120's for some reason.
As for the mean green ALT. No they don't make one for our car... you might ask them if the bigger V8 model is upgradable?
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  #14  
Old 04-10-2006, 10:53 PM
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search "al129x"
"Alternator" 115 Amp Bosch AL129X works in 123s!
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  #15  
Old 04-10-2006, 11:55 PM
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Quote:
Originally Posted by MTUpower
I had seen this before, and thank you for linking to it. I am just wanting the biggest alternator I can fit... when I heard 120-140, I was getting excited

A 115 should be fine, but I want to keep the door open for later projects.

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