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99 F250 7.3l Chronic alternator(s) failing

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99 F250 7.3l Chronic alternator(s) failing

  #1  
Old 09-13-2018, 08:20 PM
shadams3
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99 F250 7.3l Chronic alternator(s) failing

Greetings, First time posting a question. I have a 1999 F250 196,000 miles. I've replaced the batteries 2+ years ago. I've replaced the alternator "3" times with NEW alternators. Every 7 months or so the battery light comes on and off and on, till the alternator is replaced. Currently, I have had this NEW alternator in for about 3 weeks, Already my headlights dim and brighten as the battery light comes on and off and the voltage meter fluctuates up and down. The NEW alternators are from NAPA and are not rebuilt. PLEASE HELP

What amp power altenator should I be using? The alternators' I've been replacing are 110amp. Should I go higher? I do tow a 5th wheeler and an ATV trailer behind it. BUT!!! None of the altenator problems have occurred while towing.
 

Last edited by shadams3; 09-19-2018 at 10:06 PM. Reason: Additional information
  #2  
Old 09-13-2018, 09:45 PM
brandonrr
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What condition are your batteries in? Weak batteries and corroded or loose terminals will work an alternator harder and make running voltage less stable. Charging will be slower from high resistance which wastes power and creates extra heat. Heat kills alternators and batteries.

edit: just noticed the batteries are fairly new. It still wouldn't hurt to have them tested if you don't find any issues with the battery terminals, ground connections, wire condition, corrosion, etc.
 
  #3  
Old 09-14-2018, 09:54 AM
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You'd be a good candidate to do the new cable routing with alternator feeding the batteries..maybe Y2K or Sous can post a pic of what im tryn to describe
 
  #4  
Old 09-17-2018, 01:25 PM
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Following this one!
 
  #5  
Old 09-17-2018, 02:26 PM
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As requested, photos of what cured all alternator and battery problems.

Upper Alternator:
























(New alternator did not come with pulley, so this is how to harvest and remount the old pulley from the OEM alternator to the new alternator without over or under torque from an impact wrench).



Lower Alternator:



















But remember... the cure for electrical weakness could end up being the cause for glow plug failure.
 
  #6  
Old 09-17-2018, 02:30 PM
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even a 6 month old battery can be bad. Sounds like the alt is working extra hard. I would load test both batteries first. Also check for corroded connections.
 
  #7  
Old 09-17-2018, 05:34 PM
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I was not aware that NAPA sold NEW OEM alternators.
 
  #8  
Old 09-17-2018, 05:51 PM
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Whoa, that's a beautiful lifelong fix!!

Nicely done and thanx for sharing! When my unit ails, I'll be spot on with your post.

Thank you from all of us (most of us)

Denny
 
  #9  
Old 09-17-2018, 07:23 PM
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Thanks

Many thanks to everyone! The battery terminals are squeaky clean and the alternators' from NAPA are their name brand not OEM. I will have the batteries load tested as advised! I thank all y'all for your input and experience!!!
 
  #10  
Old 09-17-2018, 08:01 PM
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Shad.

Key lesson from the extent of the above post is............

Battery terminals can play a bugle cleaned, but if the rest of the system isn't as sanitary, it just won't play a tune. Dig into every ground and your starter connections as well as anything that has +/- voltage and spend some time.

Believe me. Everything lasts alot longer. Follow your Neg cables to termination and inspect along the way. Do the same as suggested with the pos side. Definiely pull cables and clean your starter connections and treat them.

Guarantee you, that thing will charge like a new truck and your starts will spin faster.

Denny
 
  #11  
Old 09-17-2018, 08:07 PM
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Thank you!

Denny,

Many thanks for the insight and experience! I will spend this Saturday doing just as you advised!
 
  #12  
Old 09-17-2018, 08:24 PM
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Originally Posted by hydro man 17 View Post
I was not aware that NAPA sold NEW OEM alternators.

They don't! They sell new clones that are made in very nice third world countries with awesome quality control. It's the same alternator you can get from DB or Fleabay. The bridge rectifier is so cheap its bound to fail. Someone opened a OEM and an aftermarket and compared. Lots of internal differences.
 
  #13  
Old 09-17-2018, 09:01 PM
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Check the alternator connections. If they are loose then you should look at replacing the pigtails. Loose connections will cause the battery light to flicker and can cause charging issues
 
  #14  
Old 09-18-2018, 10:44 PM
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I assume they're testing the failed alternators before giving a warrantee exchange; do you know what in them failed? Knowing what exactly is failing could point towards the cause of failure.
 
  #15  
Old 09-19-2018, 10:57 AM
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Not testing

Great point but they're not testing the bad altenator, just a straight switch new for old.
 

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