Changing Your Alternator Step By Step + A Question

Discussion in 'SN95 4.6L Mustang Tech' started by ked263, Aug 3, 2013.

  1. hello, so around 2 AM my battery light come up and the car thought it would be funny to die in the middle of the street , good thing I was able to get home just before the car completely die

    anyway, I had an old alternator that I know it's (working) but sometimes the batt light come on everynow and then but never die luckly ,

    and then I thought , why not trying to get it fit into the car ( which would be my first time to take part of the engine out beside the air filters and hoses and other small things )

    so here is a step by step showing how to do it and here is the question ...

    after I get everything done I take alook on the voltage (using the milage reader as voltage reader , I am sure you know how to start this by holding the trip bottun down for about 5 sec then start that car )

    anyway I am getting a reading from (15.8-16.9) and sometimes in the very first sec of running I get 18V

    but the reading is very fast , changing between the numbers ...

    is that normal ???

    here is the steps

    you will need


    disconnect the negative terminal of the batt

    start by losing the belt by pulling the tensioner to the right and get the belt off the alternator

    using the first part of the tool only


    then use a 10mm to unbolt the alternators in 4 areas in the corners

    unbolt the nut holding the charging wire and the plug behind the alternator


    now to fit the new (or my used alternator ) first put the lower bolts and tight them half way in , so you can put the alternator on them then tight them well


    make sure to put the power wire back and the plug too before putting everything back


    now to put everything back first make sure the belt is set in the right way on the other parts like crank pully etc

    then to be able to put the belt, just pull the tensioner to the right again and put it back and test the car ....

    in my case I get 17 avarage voltage at idle , is that fine ?

    now , thats the end of the story , so .... till next time :D

  2. Nice write up!

    Regarding the 17 volts at the battery. If true, this will over charge and ruin the battery. The charging voltage should be in the 13-14 Volt DC area (depending upon temperature and run time).

    Are you positive the VOM scale is set to DC Volts?

    Are you positive that all of the grounds are in place and clean? How about the grounding strap from the left hand motor mount to the frame rail?

    I don't recommend continued operation at 17 volts DC.

  3. thanks :)

    as for the vom , I am not sure, its not showing anything , just the reading ,
    and btw, I took the reading again while the engine is off, I am getting 15.1

    last thing as for the ground on left hand motor mount , I will look on it tomorrow , but (LEFT) is when I am facing the car, or I am sitting on the car. (yet I think I will only found one strap haha but till tomorrow )

    thanks again
  4. Suspect that the VOM is not accurate. 15.1 from just the battery is about 3 volts too high.

    Soooo 17 minus 3 = 14 volts which is a perfect charging voltage.

    Left and right side ALWAYS is from the car's point of view. Left side is the driver's side.
    ked263 likes this.