Dramatic alternator failure, or how my 1987 300D left me stranded.. - Page 2 - PeachParts Mercedes-Benz Forum

renaissanceman · #16 04-20-2017, 11:51 AM

How about this one:
https://www.dbelectrical.com/products/alternator-mercedes-benz-300-series-gas-1993-c-e-class-1994-2000.html

And the INA clutched pulley:

OEM INA Alternator Pulley Made in Germany 022903119C | eBay

I don't really need to up the amperage much, I just want a more modern design that is more efficient and less failure prone. What kind of wiring mods would I have to make for a 90 amp upgrade?

sixto · #17 04-21-2017, 04:03 AM

Do you need an overrun clutch with a 90A alternator? I think it's only 140A and higher alternators that have an overrun clutch as OE. I read it's related to the rotating mass of the alternator. I have 70A, 90A and 115A alternators on the shelf and I can feel the weight difference.

Sixto
83 300SD
98 E320 wagon

renaissanceman · #18 04-21-2017, 04:16 AM

I'm not sure if you need one, persay, but I have read that it increases the belt damper lifespan and quiets the belt a bit regardless of which alternator is installed.

I may just stick with the stock 70A alternator to avoid hacking up the harness. I rarely use as much power as it provides, I'd think.

renaissanceman · #19 04-21-2017, 03:57 PM

I decided to go with the 90A modern style internal fan alternator for the reduced noise and (hopefully) increased efficiency from better cooling. I also ordered a clutched pulley to help smooth out the belt drive and hopefully reduce noise and increase efficiency.

$139.58 total for the alternator, pulley, pulley installation tool and belt. Could be worse. Now I'll just have to figure out the wiring modifications and I'll be back on the road. I don't think running heavy cable is warranted for a slight increase in alternator power, so it should be pretty straightforward.

renaissanceman · #20 04-24-2017, 08:50 PM

I received the new alternator from DB electrical and INA overrunning pulley today:

I think they may have sent me the 105A vs 90A that I ordered. The INA pulley is 56mm and the stock is 50mm. Hopefully the stock belt will still fit.

tjts1 · #21 04-24-2017, 10:49 PM

Do you have the tool to install the pulley ? You will need to redo the wiring harness at the terminals to adapt to the new alternator.

renaissanceman · #22 04-24-2017, 11:20 PM

Quote:

Originally Posted by tjts1

Do you have the tool to install the pulley ? You will need to redo the wiring harness at the terminals to adapt to the new alternator.

The tool is on the way, should be delivered tomorrow. It looks like the overrunning alternator pulleys were invented in 1995, so I'm sure that it will make for a smoother accessory drive. Re-doing the wiring should not be a huge issue, I just need to get under there and figure out what all I need to do to get it wired up and working.

Mark DiSilvestro · #23 04-25-2017, 04:28 AM

When the original Bosch alternator failed on my '84 TD several years ago, I installed an upgrade used Bosch 90A unit - mainly because a friend gave the replacement to me.
I left the original B+ twin-plug harness disconnected but secured with a bracket and sleeve I made from some rubber hose, and fastened to the 90A unit. Then I piggybacked a battery cable to the 8mm B+ stud on the starter, connecting the other end to the 6mm B+ alternator stud.
I used one of those European-style battery cables that has the stamped battery terminal with a 6mm bolt. Then I removed the 6mm bolt and cut off part of the battery terminal, leaving one 6mm lug on the cable to connect to the 6mm alternator stud.
I realize my W123 engine setup is different than yours, but hopefully you'll be able to fit something similar.

Happy Motoring, Mark

renaissanceman · #24 06-02-2017, 06:56 PM

I'll probably just end up modifying the harness. I'm posted a new thread here:

http://www.peachparts.com/shopforum/diesel-discussion/386459-alternator-upgrade-wiring-questions-photos.html

It has photos of the carnage and a few questions.

Father Of Giants · #25 06-02-2017, 07:01 PM

Reading this thread scared the sh** out me.

I checked all of my pulleys and they are ok
However the water pump and alternator pulley have the slightest bit of drag and roughness to them. Going to change them before they get really bad.

compress ignite · #26 06-02-2017, 10:13 PM

http://www.w124performance.com/images/W124_stereo/white_87/

http://www.peachparts.com/shopforum/performance-paddock/53237-installed-143a-alternator-my-w124-86-95-e-class-photos-2.html

compress ignite · #27 06-02-2017, 10:19 PM

The "Special Pulley" relieves the TENSIONER system of excess load caused by
the Heavier Alt's spinning mass and inertia.
(It will also SAVE your Harmonic Balancer from the same fate.)

I believe (as Dave says) it's not really needed until you go up to 120 Amps.

renaissanceman · #28 06-09-2017, 07:45 PM

This morning I got the alternator installed, minus the wiring. Now I can at least move the car around my garage if I need to. The clutched pulley is 56mm and the stock pulley is 50 mm. Despite requiring about 10mm of extra belt as compared to stock, it worked with a stock belt no problem and the tension seems perfect, with about 1/2 inch of deflection when gently pushing on the top span of the belt.

It's smooth as silk and much quieter. I'm a happy customer. I don't really want to run new wiring, so I'll probably just hack the stock harness. I'll never put the old-school style alternator back in there now that I have a modern one.

I highly recommend the clutched pulley upgrade, even with the stock 70A or near-stock 90A unit. There is a reason that all modern cars use clutched pulleys. I have heard a 1-2% bump in fuel efficiently is to be expected with that upgrade.

barry12345 · #29 06-09-2017, 08:32 PM

Quote:

Originally Posted by BillGrissom

I always carry some 1/4" nylon rope. One use is to tie a loop to turn just the water-pump pulley. I did that when my alternator bearing seized, squealing the belts. Trick is to tie a barrel knot (like fishing) and get the rope taught. If you get the diesel started, you won't need any more battery until you get home, unless driving at night. Hitting 120 C for a short time will not hurt the engine. Indeed, the temp sensor in my 1984 & 85 300D's will show excessive temp from just an air pocket by the sensor.

Or a dollar pair of panty hose in the trunk. Can save you various responses when asking the ladies if they can spare their panty hose.

renaissanceman · #30 06-21-2017, 04:23 PM

So I finally got an adapter harness built and installed this morning. I fired her up and all was well -- I had 11.8v at the battery without the engine running, and then when I started it, that reading jumped to 13.6v. Perfect!

I let it idle for 5 minutes or so while cleaning up the work area and then shut her down. I buttoned everything up and put on the bottom pan, and started the car again to take it off the ramps, and all the lights were lit up on the dash just like they were when the original alternator failed. I measured the voltage at the battery and it had dropped to 11.8v while running. Shut the engine down and the battery was up to 12.0v.

All the wiring was intact, and I didn't see any smoke. The alternator was quite hot to the touch. WTF?

I'm pretty pissed that I spent an entire workday morning screwing with this car just to have something immediately fail...

Is the alternator fubar, or is there something else I should check before proceeding to rip it all out again and start over. #$@%$