# How to replace alternator on 7.3 diesel 99 F450



## Emerscape (Mar 23, 2005)

ive gotta go get a new alternator for my f450 7.3 diesel. How hard is it to replace and how do you go about doing it? Any help would be greatly appreciated


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## earnies2 (Feb 20, 2003)

Did you test it? check the belts. if you need a hand call me (781)461-2550


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## rancherman84 (Oct 22, 2005)

1 unhook negative batt. cables
2 find the tensioner for the serpentine belt and use a suitable wrench to slacken the belt and remove it from the alt.pulley
3 unhook all wires from the alt
4 remove the mounting bolts holding the alt. to the bracket,and remove the old alt.
5 reverse procedure to reinstall new alt.
nothing to it


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## MickiRig1 (Dec 5, 2003)

Take the old alternator with you and have it tested. 
I would invest in the serpentine belt tool,it's a flat 3' bar it comes with short sockets and claw foot wrench's.It's well worth the $16 -- $20 cost. You can amaze your family and friends with how easy it is to change belts with the right tool.


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## Emerscape (Mar 23, 2005)

yup i brought the truck to autozone and they tested the batteries and alternator. Ive gotta order one and then take a shot at changing it. Doesnt sound hard just wanted to make sure before I do it. I appreciate the help Ill keep you guys updated.


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## MickiRig1 (Dec 5, 2003)

Buy the repair manual for your truck,make sure it covers the diesel.
Auto Zone has them ($15 or so) and can order them for you.
You have to be careful trying to fly blind into repair jobs. The book gives you cautions and procedures to get the job done right.You can read the procedure and tell if it's over your skill / tool level. If you can't find it in your book, go to a bigger public library. Most times they have the "Motors" pro manuals and other useful resources.


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## earnies2 (Feb 20, 2003)

Im supprised they did'nt have it on the shelf ! i have the surpentine belt tool but all you need is a 15mm socket and a long ratchet. If you want to charge your batteryes and come to Dedham i will change the altonater for you make shure you get a belt. let me know


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## Mark Witcher (Feb 21, 2004)

I have a 96 ford diesel. To take the tension off the belt, you just put a wrench on the center bolt on the tensioner pulley and pull it back.The 99 is most likely very similar. You will also need an impact wrench to take the pulley off the alt..
The Haynes/Chilton manuals are a joke. If you plan on keeping this rig and doing any repairs your self, get a factory manual.


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## GFX (Sep 6, 2005)

This is all of a 10 or 15 minute job for the primary alt. 

1/2 rachet with a short pipe or a 1/2 breaker bar to remove belt. Three bolts on the alt, 2 wire connections and it's off. 

Very simple. Don't go buy a manual for this job. Save your money!!


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## MickiRig1 (Dec 5, 2003)

You should always have "the book" on your truck!
It gives you trouble shooting,procedures,locations of parts and filters.
You can not fly blind into repairs/ maintenance on trucks.
There are procedures that need to be followed on most repairs and if you don't, it could shorten the life of the part or cause dangerous problems later on.


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## Dirt_Werx (Nov 26, 2005)

Mick is right, even though it is a very simple procedure ive done a hundred times, get the manual, there are some things such as installing it with batteries that are fully charged or you will never get great charging out of the alternator ect. If the book dosn't come in handy on this job it will on another, whats 15$ to keep a 40k$ truck running right.


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## MickiRig1 (Dec 5, 2003)

If the book is vague you can go to a bigger library they have pro manuals.
A big procedure repair I always go and look at least 1 more manual. I have had the Ford shop manuals too they can be vague on a some stuff. They tend to send you to the Ford spacial component manuals for those repairs and trouble shooting. Like he said you can't risk a 40k truck for want of a $15 manual.


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## earnies2 (Feb 20, 2003)

I was reading the posts and we all forgot 2 important things 1 st is to count the ribs on the pulley or change the pulleys out if tou look at a 6 gruve or a 7 gruve they look the same until you eat up a $50 belt!!! and 2 nd is to charge the batteryes so you dont smoke the new altonater it takes time for the brushes to seat before full amps can be made so you dont want the brushes arching out becaus thier not seated!!!! just my .02 Have you got your truck fixed yet???//


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## Dirt_Werx (Nov 26, 2005)

ya i had mentioned he should make sure the batteries are fully charged but good point about the belt. good luck emerscapes and dont hesitate to get in touch if you need a hand, i have shop space in walpole/sharon and could possibly help you out if ya needed it.


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## MickiRig1 (Dec 5, 2003)

Our mechanics at the ambulance company clean off a section of white painted surface under the hoods. They then write the belt number and the amount of quarts of oil it takes with a black permanent marker. This saves a huge amount of time for them at just a glance at the info. I did it with my vehicles,the first Windstar took 4.7 qts oil,the new one takes 6.
I guess I got the heavy duty Taxi model somehow?


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## Ggg6 (Oct 14, 2003)

I am sure Black Cloud meant the job is very simple and the manual is not needed for this particular job. He would agree the manual is a wise investment. He was also correct in that you do not need a serpt. belt wrench all you need is a 1/2" breaker bar, there is a 1/2" square hole for loosening the belt tensioner. Disconnect BOTH batteries. There are three mounting bolts on the top of the alt. I think they are 5/8 hex. two wire connections to remove. 
Install- No belt, or alt. position adjusting upon install, just bolt it back on and connect the wires and install the belt. Be certain to charge the batteries with a battery charger before doing the job. You do not want to ruin a new alt. by trying to charge low batteries with it. (been there done that mistake) I would say if you can change a flat tire you can do this.
Welcome to the site Garrett.


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## Emerscape (Mar 23, 2005)

hey guys. sorry that i havent provided an update. Ive been buried at work with Hurricane Katrina files (Im a forensic accountant) and havent had a minute to even get onto plowsite. I had trouble ordering the part through autozowne and actually ordered it yesterday through the local ford dealer. Suprisingly enough I can get a brand new alternator from FOrd for about 50 dollars more than a remanufactured alternator from autozone. Im taking a half day tomorrow (friday) so I am planning to at least replace it tomorrow. I dont have a breaker bar but maybe can pick one up tomorrow. Then i gotta find a battery charger (probably have to run down to plympton) to charge both the batteries up. Does anyone know if autozone will charge your batteries for your.. I know it sounds stupid and that I should buy a charger but the apartment complex i live in i dont have room and cant run extension cords. Thanks for the help everyone i really appreciate it. Now i just gotta pray for snow or at least someone to buy my truck.


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## Emerscape (Mar 23, 2005)

hey guys. sorry that i havent provided an update. Ive been buried at work with Hurricane Katrina files (Im a forensic accountant) and havent had a minute to even get onto plowsite. I had trouble ordering the part through autozowne and actually ordered it yesterday through the local ford dealer. Suprisingly enough I can get a brand new alternator from FOrd for about 50 dollars more than a remanufactured alternator from autozone. Im taking a half day tomorrow (friday) so I am planning to at least replace it tomorrow. I dont have a breaker bar but maybe can pick one up tomorrow. Then i gotta find a battery charger (probably have to run down to plympton) to charge both the batteries up. Does anyone know if autozone will charge your batteries for your.. I know it sounds stupid and that I should buy a charger but the apartment complex i live in i dont have room and cant run extension cords. Thanks for the help everyone i really appreciate it. Now i just gotta pray for snow or at least someone to buy my truck.


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## Ggg6 (Oct 14, 2003)

Depending on how low your batteries are it could take a few hours to charge them fully, I would guess Autozone will not do it. I am supprised they did not have the alt. in stock.


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## Emerscape (Mar 23, 2005)

decieded to take a "half day" at work and come home to tackle the alternator. Took me probably 15 minutes to pull both batteries and the alternator. Made a quick trip to the ford dealer and picked up my alternator and dropped off both batteries to be charged. Came back and popped the new one on.. the belt took me the longest i think because i wasnt sure how i was gonna pull it back. all set now just waiting for the batteries and im back in business. thanks guys.. now lets pray for some snow


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## Dirt_Werx (Nov 26, 2005)

emerscape, were sposed to get slammed monday night and tuesday, get that truck back in action.


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