ALTERNATOR REPLACEMENT - Montana Owners Club

jackel1959 · 12-09-2009, 03:05 AM

I have a 2002 F-250, 7.3L PS and it looks like I have to replace my alternator (it is only showing 12.3-12.5v output). I have changed alternators out before, but have never dealt with a serpentine belt. So my questions are:
1. How do I get the belt off and then back on at the proper tension?
2. What AMP output is my alternator (I have the single set up)?
Thanks in advance,
Jack

jimcol · 12-09-2009, 03:55 AM

Jack, I can't answer the alternator output question but the serpentine is easy. You will need to put a socket on the tension pulley to take the tension off the old belt. Watch exactly how the old one goes around all the pulleys. There should also be a diagram somewhere n top of the engine near the top of the radiator shroud. Once you remove the tension take the old belt off. Install the new belt the same way as the old. The last step is to put the socket back on the tension pulley, Pull it up and place the new belt under the pulley, release the tension on the socket and you are done. The spring in the tension pulley applies the correct pressure to the belt. Easy job. Good luck, Jim

jackel1959 · 12-09-2009, 05:13 AM

Quote:

quote:Originally posted by jimcol

Jack, I can't answer the alternator output question but the serpentine is easy. You will need to put a socket on the tension pulley to take the tension off the old belt. Watch exactly how the old one goes around all the pulleys. There should also be a diagram somewhere n top of the engine near the top of the radiator shroud. Once you remove the tension take the old belt off. Install the new belt the same way as the old. The last step is to put the socket back on the tension pulley, Pull it up and place the new belt under the pulley, release the tension on the socket and you are done. The spring in the tension pulley applies the correct pressure to the belt. Easy job. Good luck, Jim

Jim,
Thanks for the reply. I saw the diagram for the belt and it does say to release the tension to turn the tensioner CCW. I wasn't sure how to reapply the tension. I just got back from the auto parts store with a new alternator. It is 110A output and apparently the only one made for my particular model. I am on my way out the door now to do the install. I'll let you know how it goes.
Jack

Art-n-Marge · 12-09-2009, 05:29 AM

You might try a call to the Ford service center and ask them about the output voltage. I would hope someone would be willing to find the answer to that question without charging you.

DO NOT attempt to remove the serpentine until you find the diagram. Then compare the diagram to your truck to ensure you identify how it matches and that each turn in the diagram has a matching turn in the engine. When that's understood THEN remove it. Jimcol has the procedure down 100%.

The real key is locating the tensioner and manipulating the tensioner to work the belt out. Beware some vehicles have a nut or bolt to loosen the tensioner. In this case the tightness of the belt will be your call. I have a feeling your truck uses the spring loaded tensioner.

Trailer Trash 2 · 12-09-2009, 05:53 AM

When I did mine I took lots of pictures with my camera to help me remember how it was along with the decal on the support above the radeator.

jackel1959 · 12-09-2009, 07:09 AM

Thanks for all of your inputs. Once I located the hole on the tensioner pulley bracket to insert the breaker bar into, everything else was a piece of cake. The alternator is replaced and I now have 13.9-14.2 Volts at idle with a load (headlights on, blower motor on HI).
Jack

Tom S. · 12-09-2009, 08:40 AM

It's too late now, but while you were at it, you should have replaced the belt too, especially if it has never been replaced. Then through the old one in the tool box for a spare.

jackel1959 · 12-09-2009, 04:32 PM

Quote:

quote:Originally posted by Tom S.

It's too late now, but while you were at it, you should have replaced the belt too, especially if it has never been replaced. Then through the old one in the tool box for a spare.

Tom,
I had a new belt installed 17K ago, otherwise I would have replaced it too.
Jack

noneck · 12-10-2009, 01:12 PM

I had mine go last year and it set the dash alternator indicator warning. I'm thinking of changing my belt out this spring as a preventive maintenance task...

jackel1959 · 12-10-2009, 06:00 PM

Quote:

quote:Originally posted by noneck

I had mine go last year and it set the dash alternator indicator warning. I'm thinking of changing my belt out this spring as a preventive maintenance task...

This is the second alternator I have replaced in 7+ years. The first one was done under warranty and this one out of pocket. At least this one has a lifetime warranty. Neither of the failures gave me a dash board light. I have an after market gauge (ScanGauge) which shows me charging voltage along with a bunch of other selectable functions. When I saw the drop in voltage, I knew I had a problem.
Jack

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