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AirheadNut
Member
Date registered: Nov 2016
Location: Montana
Vehicle(s): 1988 280GE SWB
Posts: 31
| 300GD Alternator Upgrade Options
Last week while on a trip the low voltage light started to flicker and the voltmeter began to read 12.4-12.8V instead of the usual 14.2V. I checked the belts and they were very loose. However, when I went to retighten them I found that the mounting holes on the alternator are too big for the bolts that go through them, causing the alternator to sit at an angle relative to the belts. This has caused wear on the alternator pulleys and makes it so that I cannot properly tension the belts. I also think that the current alternator is on its way out. Does anyone have a recommendation on an alternator upgrade that will mount properly to an OM617? I am looking for something that can handle reasonably heavy loads (dual batteries, power inverter, air compressor, winch, etc). |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: 300GD Alternator Upgrade Options
If the alternator has worked well in the past, how about shimming the mounting holes in the alternator? |
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AirheadNut
Member
Date registered: Nov 2016
Location: Montana
Vehicle(s): 1988 280GE SWB
Posts: 31
| RE: 300GD Alternator Upgrade Options
I considered shimming, but I think that the alternator is failing. However, if there is a voltage regulator or something else that would be more likely to cause the low voltage I would rather figure that out before getting a new alternator. |
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Aircruiser
Extreme Veteran
Date registered: Aug 2011
Location: Atlanta GA
Vehicle(s): 2000 G500, 1986 300GD, 2017 Porsche Cayenne Hybrid
Posts: 364
| RE: 300GD Alternator Upgrade Options
The voltage regulator is the most common failure point for you alternator from what I've heard and in my experience. It is a quick fix.
http://www.eurotruck-importers.com/index.php?main_page=product_info...
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Inkblotz
Expert
Date registered: Apr 2006
Location: Georgia
Vehicle(s): 90 300GD "Thundering Turtle II", w/ 603A turbo
Posts: 3186
| Re: 300GD Alternator Upgrade Options
Check out this older post: http://www.pointedthree.com/disc/forums/showthread.php?tid=17122&po...
Replace the mount or it will ruin the new alternator.
https://www.dieselmercedes.com/Mercedes_Alternator_Bracket_for_OM615...
Edited by Inkblotz 4/12/2017 6:43 AM
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AirheadNut
Member
Date registered: Nov 2016
Location: Montana
Vehicle(s): 1988 280GE SWB
Posts: 31
| RE: 300GD Alternator Upgrade Options
Thanks everyone for your help! On further inspection I believe that I already have an AL129X (or something that looks very similar). The lower mounting bolt is frozen right now, so I haven't been able to remove the alternator. When I do, I will have it tested, and if it is okay I will look further for the low voltage issue. It looks like the stock voltage regulator is mounted on the alternator itself? Does the AL129X have its own regulator, or would it need an external regulator? Since I don't have a stock alternator anymore, I am not quite sure where to look for a regulator. Also, the charge light has been randomly going off every once in a while, almost like there is a wiring short. |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: 300GD Alternator Upgrade Options
That is the classic sign of worn alternator brushes. They come as part of the regulator, which is built in. Depending on hose routing you may be able to get the regulator off of the back of the alternator with it in place. 1) disconnect battery 2) remove back cover of alternator 3) two screws hold the regulator/brush pack on. 4) reverse to re-assemble.
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Aircruiser
Extreme Veteran
Date registered: Aug 2011
Location: Atlanta GA
Vehicle(s): 2000 G500, 1986 300GD, 2017 Porsche Cayenne Hybrid
Posts: 364
| RE: 300GD Alternator Upgrade Options
AirheadNut - 4/13/2017 1:00 PM
Thanks everyone for your help! On further inspection I believe that I already have an AL129X (or something that looks very similar). The lower mounting bolt is frozen right now, so I haven't been able to remove the alternator. When I do, I will have it tested, and if it is okay I will look further for the low voltage issue. It looks like the stock voltage regulator is mounted on the alternator itself? Does the AL129X have its own regulator, or would it need an external regulator? Since I don't have a stock alternator anymore, I am not quite sure where to look for a regulator. Also, the charge light has been randomly going off every once in a while, almost like there is a wiring short.
That lower bolt can be a real PITA, it took me three days with PB Blaster, heat, ruined a craftsmen 1/2" ratchet by using an improvised breaker bar extension, one painfully slow click at a time, it was stubborn the entire way out. I had the greatest success by using multiple extensions, universal joints and an impact gun from behind the front axle once the bolt is broken free.
Good luck! |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: 300GD Alternator Upgrade Options
Aircruiser - 4/14/2017 7:58 AM
That lower bolt can be a real PITA, it took me three days with PB Blaster, heat, ruined a craftsmen 1/2" ratchet by using an improvised breaker bar extension, one painfully slow click at a time, it was stubborn the entire way out. I had the greatest success by using multiple extensions, universal joints and an impact gun from behind the front axle once the bolt is broken free.
Good luck!
Is this on the 300GD or the G500? |
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Aircruiser
Extreme Veteran
Date registered: Aug 2011
Location: Atlanta GA
Vehicle(s): 2000 G500, 1986 300GD, 2017 Porsche Cayenne Hybrid
Posts: 364
| RE: 300GD Alternator Upgrade Options
The 300GD.
I haven't had the need to remove the alternator on my G500 yet but wouldn't expect it to be nearly as stubborn. |
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AirheadNut
Member
Date registered: Nov 2016
Location: Montana
Vehicle(s): 1988 280GE SWB
Posts: 31
| RE: 300GD Alternator Upgrade Options
Aircruiser - 4/14/2017 5:58 AM AirheadNut - 4/13/2017 1:00 PM Thanks everyone for your help! On further inspection I believe that I already have an AL129X (or something that looks very similar). The lower mounting bolt is frozen right now, so I haven't been able to remove the alternator. When I do, I will have it tested, and if it is okay I will look further for the low voltage issue. It looks like the stock voltage regulator is mounted on the alternator itself? Does the AL129X have its own regulator, or would it need an external regulator? Since I don't have a stock alternator anymore, I am not quite sure where to look for a regulator. Also, the charge light has been randomly going off every once in a while, almost like there is a wiring short. That lower bolt can be a real PITA, it took me three days with PB Blaster, heat, ruined a craftsmen 1/2" ratchet by using an improvised breaker bar extension, one painfully slow click at a time, it was stubborn the entire way out. I had the greatest success by using multiple extensions, universal joints and an impact gun from behind the front axle once the bolt is broken free. Good luck! Thanks - I think. Great information, but not looking forward dealing with a very frozen bolt...I will probably give it a shot this weekend. I still can't get over how much fun this thing is to drive, despite the occasional quirk. |
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Razon
Date registered: Jul 2008
Location: Vancouver, BC
Vehicle(s): 1986 280ge Cabrio, 617A, 5sp manual
| RE: 300GD Alternator Upgrade Options
Make sure you're not trying to remove the "bolt" that's actually a nut welded to the bracket. The bolt is from the other side.
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emlmcb
Veteran
Date registered: Dec 2006
Location: Buenos Aires, Argentina
Vehicle(s): 1986 LWB 300GD / 1998 E320 / 1996 LWB G300TD
Posts: 119
| RE: 300GD Alternator Upgrade Options
I had endless problems with the alternator of my 300GD until I found that the problem was the tachometer.
Unlike other diesels that have an independent sensor, the original tach of the 300GD takes its signal from one of the diodes of the rectifier bridge in the alternator.
The wire leading to the tachometer was peeled off somewhere and it grounded the diode. A new wire solved the problem forever after having changed a few diodes and even a whole alternator. |
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