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#1
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Dying Alternator
Well, the alternator in my 240D is starting to go. At idle this morning my lights dimmed and the battery light comes on. When I was looking around at the site where I got my valve adjusting wrenches I saw that he suggests replacing the voltage regulator on the alternators on older mercedes as a preventitive maintance procedure. Is this something worth checking out or should I just replace the alternator? Also, if I should do the alternator I saw that there are 55 and 65 amp ones avaliable. The 65 amp ones are about $50 more. Is there any reason for the 65?
Thanks!
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Michael Roth 1982 300TDT Wagon 1982 240D Euro!, 4spd manual-Parts car now, dead engine 88 Jeep Grand Wagoneer-fixing up for offroading 1989 Ford F150 (rust bucket) For Sale! 1953 Dodge B-4F, 1 1/2 ton Stake Bed (new restoration project) |
#2
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Check your options too as I think some of these had brushes that could be replaced and only cost about 3.00 or soemthing like that.
I could be wrong but would sure beat a new alternator. As for bigger is better? It's really a matter of application. If you do a lot of short hop night driving then yes, the bigger alternator is best for you. I doubt you tow with your MB so you don't have that extra draw from a trailer to worry about so personally, I think for the extra money I would just stay with the original alternator.
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'99 S420 - Mommies '72 280SE 4.5 - looking to breathe life into it '84 300SD Grey - Sold '85 300SD Silver - Sold '78 Ski Nautique |
#3
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McRoth
These regulators are easy to replace from topside. I replaced mine then for $1.00, at my local auto electric shop, bought new brushs and soldered them into the old regulator which is a spare. When you take the regulator out (2 screws) if the 2 brushs are very short or uneven thats most likly your problem. If you replace the regulator and you still have the problem at least you will have a spare regulator and will know how to install it.
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![]() 1985 Euro 240D 5 spd 140K 1979 240D 5 spd, 40K on engine rebuild 1994 Dodge/Cummins, 5 spd, 121K 1964 Allice Chalmers D15 tractor 2014 Kubota L3800 tractor 1964 VW bug "Lifes too short to drive a boring car" |
#4
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McRoth,
I replaced the alternator brushes in my 300SD 12 years ago and its still working fine after 120,000+ miles. Its probably due for new brushes soon so I carry a spare V reg with brushes if I should need to replace them again. Its such an easy fix, I could do it roadside if necessary. So I suggest you first replace the brushes. It will save you some bucks and it is much easier than replacing the alternator. As far as the 65 amp alternator, the car made it this far without needing a larger alternator, so why does it need a larger one now? Unless you have installed a lot of auxiliary electrical equipment, you don't need a larger alternator. P E H |
#5
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That's all good news! I was hoping it would be an easy quick & cheap fix!! I'll pull the old one out tonight to make sure.
Thanks Again!
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Michael Roth 1982 300TDT Wagon 1982 240D Euro!, 4spd manual-Parts car now, dead engine 88 Jeep Grand Wagoneer-fixing up for offroading 1989 Ford F150 (rust bucket) For Sale! 1953 Dodge B-4F, 1 1/2 ton Stake Bed (new restoration project) |
#6
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Well, I went out at lunch to check the alternator & someone must have already replaced it with one that doesn't have an external voltage regulator!!
![]() Thanks again for everyone's help.
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Michael Roth 1982 300TDT Wagon 1982 240D Euro!, 4spd manual-Parts car now, dead engine 88 Jeep Grand Wagoneer-fixing up for offroading 1989 Ford F150 (rust bucket) For Sale! 1953 Dodge B-4F, 1 1/2 ton Stake Bed (new restoration project) |
#7
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McRoth,
You still may be able to replace the brushes in the Motorola alternator. All alternators use brushes to get the excitation current to the rotating field. It just might not be as easy as a Bosch. If you get a replacement, get a Bosch. P E H |
#8
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PEH, Thanks, I'll give that a try before I get a replacement. I was afraid you'd say to get the Bosch, it's almost $60 more than the ac delco. Probably the best way to go though. I'll pull the old one & look for brushes before I replace it.
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Michael Roth 1982 300TDT Wagon 1982 240D Euro!, 4spd manual-Parts car now, dead engine 88 Jeep Grand Wagoneer-fixing up for offroading 1989 Ford F150 (rust bucket) For Sale! 1953 Dodge B-4F, 1 1/2 ton Stake Bed (new restoration project) |
#9
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I ended up replacing the alternator this morning. I got a rebuilt Bosch yesterday just in case I couldn't do anything with the one that was in there. I goofed on the price, the ac delco was actually the rebuilt Bosch! Anyhow, after getting the old one out I found that the bearings were pretty much shot, so I didn't even bother checking the brushes. The new one went in easily & so far everything is good. It only took less than an hour, I LOVE working on these old Mercedes!
Anyone ever noitce that when working on cars they almost always demand a blood sacrifice?!! Mine took a almost dime size chunk of skin off the knuckle of my left hand middle finger, this time. It was bleeding over everything until I was done!! I REALLY should find a good pair of light gloves to wear when working on there! Later, & thanks for all the help!
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Michael Roth 1982 300TDT Wagon 1982 240D Euro!, 4spd manual-Parts car now, dead engine 88 Jeep Grand Wagoneer-fixing up for offroading 1989 Ford F150 (rust bucket) For Sale! 1953 Dodge B-4F, 1 1/2 ton Stake Bed (new restoration project) |
#10
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Try replacing the carbon brushes and cleaning the contact points with an electric contact cleaning spray. Also test the voltage regulator.
I think with this should be able to go for another100K. LOL the core on these alternators are pretty sturdy. They do last for a while. Its either the regulator or brushes or both. MVK
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One penny saved is three penny earned. 1985 300D Turbo 179,000miles |
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