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    1. Antique and Classic Mack Trucks General Discussion

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      This forum is for general discussions about modern Mack Trucks! Granite, Vision, Rawhide, Pinnacle...etc. Specific topics can be posted in the forums below.

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      Forum for discussions about Fire trucks and specialized fire fighting equipment.

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    3. Other Truck Makes

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    4. Transportation Board

      This forum is for posting and finding transportation opportunities for your antique hobby trucks and parts around the country. Please keep rates reasonable when posting a route...

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    5. Watt's Truck Center   (222,974 visits to this link)

      Click here to visit the Watt's Truck Center Home Page featuring The B-Model Store and tons of other parts for Antique and Classic Mack Trucks including R-Models, Super-Liners, DM's and all current models!

    6. Product Announcements & Group Buys

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  6. Shows and Events

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  7. Site Related

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    2. BMT Wiki Support Topics

      This forum will hold the support topics created from the Wiki System.

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    3. Test Forum

      This is the place to practice posting photos or testing code. Topics may be removed at any time...

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    1. Mack Trucks Memorabilia Collectors Club Topics

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  • Latest Posts

    • Diode trio and connection marked in black https://www.ebay.com/itm/302551471197  
    • Ok, that is good news, You do have power to the alternator, so a wiring fault between it and the batteries is unlikely. In North America these are referred to as "one wire" type alternators, A bit of misnomer on the L/N because the case isn't the "ground" for the alternator. They "turn on" by residual magnetizem in the rotor producing a small amount of current in the stator, which runs through a separate set of diodes (diode trio) and is fed  back into the field (rotor) regulator to turn it on. The regulator also is connected to the main output studs internally so when it turns on can supply battery to the field.  The little wire between the two big wires is the feed from the diode trio to the regulator, to tell it to turn on. If your electrical guy doesn't know this, he may have supplied external power to that wire and the regulator turned on and worked. If that is the case the diode trio is the problem. It is the white piece that is connected to the three small studs and has the wire coming out of it to the little ring terminal up by the regulator. That trio is replaceable I am assuming (never a great thing) that he knows how to test the output current and main rectifiers when he did get to to charge on the bench. So assuming that is true it looks like you need a diode trio.
    • Thanks for the replys...I should have pointed out the pictures were taken before work started,more to show what type of alternator is on the truck. So far we have ... Replaced belts Cleaned all connections Done voltage tests at batterys..12.4v Voltage test at alternator also 12.4v Test lamp also lights up across the altenator terminals as decribed by Paul No change in voltage at alternator with engine running. Alternator put out 14.6v on test bench...but stays at 12.4 when in truck. The auto electrician we went to has a great reputation in our area but is a young guy.He did admit to me he has never seen an alternator with only 2 terminals.All the alternators he is use to have 3 terminals.The 3rd is connected to the charging light on the dash.This shows the driver if the vehicle is charging but also excites the alternator on start up.With only 2 terminals and no light on the dash he was wondering how the alternator is excited on start up. With all our batterys,wireing,connections and grounds checking out as in good condition we are scratching our heads wondering why the alternator will charge on the bench but not in the truck..... Thanks for reading guys. Paul
    • 100% correct, if someone isn't competent with basic electrical knowledge a test lamp is far better than a multimeter  Understanding how to read the instrument and interpret the results correctly comes from propper training and thorough understanding of what people are doing  So a basic test lamp is adequate at this stage    Keep it simple and let's not over complicate things  KEEP IN MIND YOU MIGHT HAVE TO SCRATCH AROUND A BIT ON THE STUDS AND CONNECTIONS TO GET A GOOD READING so maybe get some emery cloth and clean the nuts, lugs and studs up spotlessly clean before you begin testing, I doubt this is your issue but it gives you a good spot to start testing  and yes big dark letters because this is really important to give propper test results  Grab a test lamp, see if you have power at the alternator or not First thing first, alligator clamp on the negative ( - ) battery terminal and the pointy end on the positive battery terminal ( + ) , the lamp should light up, if it doesn't you might have a dud globe in the tester That is your most important test, always test the tester on a known lice supply  Then grab your test lamp, alligator clamp on stud I circled in black, with the key turned on put the probe end on the stud circled in red, does the globe in test lamp light up ? If yes skip a few steps here If no, then shift the alligator clamp to a good clean ground or frame or better still to the battery terminal marked -  Try again on the stud circled in red, if you have power at the terminal the fault is between the negative ( - ) terminal and the alternator  If no power put the alligator clamp on the positive battery terminal ( + )  test between the stud circled in black  You should have power here if not Try testing further back were the ground strap from the alternator bolts to the frame  Still no good test back to were the battery lead bolts to the frame and so on If yes from above, follow the same principle as the the negative, slowly test back through the circuit, tracing out wires etc until you get the lamp to light up  When it lights up you have gone passed the fault I think it will be something simple here to find if you know what your doing and a slow frustrating job if you don't  But stay patient and we will help as best as we can  But if to much bull shit advice, like I reckon, or old mate says these always do And so on I'll butt out as it becomes messy over the internet    Paul
    • Just the ol dogs parked up with eachother. Need to get the B fired up again and out of the weeds. The other R was my Dad and Grandpa's first Mack, it was a good runner until a rod went. Would like to find another e6-300 for it.   
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    • Joey Mack

      https://www.ebay.com/itm/335977440629?_skw=mack+e-tech+engine+book&itmmeta=01JWA20VWGWWKW84MXA7SPSVRS&hash=item4e39d0e575:g:fUEAAOSw~n9ncrwC&itmprp=enc%3AAQAKAAAA8FkggFvd1GGDu0w3yXCmi1dw4WewTekYgqfyNRuEV27xatvWtbt3pHWRVGQe1%2FuiJa1RXu7clyGRSUOQsiJw2vkNZsCj2oCM0P%2FFfzicknbJ1jIfvRTaeEwAuEcAvnENHMOemQfy4z6CxAOg99H0CnBQ9VW5EziMtlSRPRkvE81SM8Z%2FUbIxgXyjlUqWNlPuqLRMliIAbmsBP3PTti0ZA8IFxHf9n2peaIf5BC4NH3pXsXiboMiV%2FMHZZWAulEsSdv3ivPWd6jwPksv6HdtaD5SBBgzXSe4hxqy9vF2g39rCKjthzr7%2FBmBw7UN0Qu2Jbw%3D%3D|tkp%3ABk9SR7C-g8LiZQ
      Stoneandsteel... You need this book!
      · 0 replies
    • down4glamis  »  Mike6024

      Hey Mike! Sorry to bug ya on here, I just bought a pallet of wine in Napa and think you may have done the same. I bought the blue label and it said you won the yellow label. I was wondering if you would be up for trading a few cases so we arent stuck with so many of just 1 type of wine?
      · 0 replies
    • StoneandSteel  »  Joey Mack

      Quick question on the advice you gave me about my ai400 cam/lifter replacement kit. 
      would you have a rough estimate on the time it would take to do the actual replacement with kit? I have everything removed I’m just ready to open up the front of the engine and get to the cam. Thanks 
      · 15 replies
    • TurdFerguson

      Looking for jake adjustment screws for E6 300 2 valve Jacobs number is 2034 Mack number is 4559-2034. I would really like 12 but would take six.
      · 0 replies
    • jefferydixonsr  »  h67st

      Hi I have a 1969 685t r model mack  I'm looking for the front axle spin on hub oil caps if someone has some that they want to sale or know where I can get some I know the old b model had the same thing that thread overfront hub or spock if you can help me out thanks 
      · 2 replies
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