Blown alternator from welding.
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Fleet Mechanic
Joined: Apr 2011
Posts: 1,441
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From: Marseilles IL
Blown alternator from welding.
I was doing some mig welding on my 2000 superduty Saturday night. I took the usual precaution and disconnected both batteries. The previous owned made there own under bed braces for the gooseneck hitch and I was reinforcing them. I had a piece of angle iron clamped in place against the frame and the ground clamp for the welder on the new piece to be welded on. After puting everything back together I drove home. I wake up the next day and I find my less than a year old alternator is toast. Could it be from welding? Could it be that I disconnected the negative battery cable off of both batteries instead of the positive cables? Just a coincidence? I am the only one that disconnects my batteries before welding ,my friends weld on trucks and jeeps all the time and never disconnect there batteries and I'm the one to have a problem. Go figure! Anyone have any ideas?
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
I've known lots of folks who have welded on their trucks with no problems. And I've heard horror stories about a friend of a friend. Kind of hard to say, but since the alternator still has a power wire connected to it, and it grounds to the motor through it's mount, anything is possible.
Then again, if it's an Autozoo rebuilt alternator, then it's about due to fail based on the ones I went through.
Then again, if it's an Autozoo rebuilt alternator, then it's about due to fail based on the ones I went through.
Posting Guru
Joined: Oct 2008
Posts: 1,080
Likes: 10
Possible..... Probable.
Hope you didn't damage your PCM or IDM. Although with the ignition off you should be okay.
Always disconnect all cables. I also wrap them in a towel. I've seen them arch to the Radiator bracket from a few inches away. It had exposed copper from when the owner replaced the ends. That'll wake you up. I don't think the lead would have done it.
Of course were Arch Welding fish plates on a frame.
Hope you didn't damage your PCM or IDM. Although with the ignition off you should be okay.
Always disconnect all cables. I also wrap them in a towel. I've seen them arch to the Radiator bracket from a few inches away. It had exposed copper from when the owner replaced the ends. That'll wake you up. I don't think the lead would have done it.
Of course were Arch Welding fish plates on a frame.
Postmaster
Joined: Dec 2010
Posts: 2,951
Likes: 4
From: Gary,Indiana
Since you were mig welding I really don't think it was the cause of the alt going out. I use to be in the body shop business and as a rule of thumb we always disconnected neg battery lead first and then positive lead per ASE/ ICAR for welding. And if welding within 12" of ecm, pcm or gem you should remove said ecm. After 25 yrs in the body shop business I have only seen a few times that welding did any damage. Mostly GEM, ECM and the other time on a BMW 3 ecm's at once. But on the BMW the battery was hooked up and the key on. That tech was fired.
I'll bet it was a reman from local parts store that just gave out like Chris said. If you haven't replaced it yet. I would go with a NEW 6.0 alt. Don't do reman I never have any luck with parts stores reman done in China or Mexico. I am running a new 6.0 alt from ORielly's or was it Advance with no issues so far.
I'll bet it was a reman from local parts store that just gave out like Chris said. If you haven't replaced it yet. I would go with a NEW 6.0 alt. Don't do reman I never have any luck with parts stores reman done in China or Mexico. I am running a new 6.0 alt from ORielly's or was it Advance with no issues so far.
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Yes it's a higher output, slightly larger case, and going with new instead of reman seems to make a world of difference. Over 2 years on mine and still running like a champ as opposed to the annual autozoo swap I used to deal with.
https://www.ford-trucks.com/forums/1...lternator.html
https://www.ford-trucks.com/forums/1...lternator.html
FTE-Spread The Knowledge
Joined: Feb 2008
Posts: 2,285
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When you turn off the welder the magnetic field collapses and creates a pulse or inductive spike. To prevent the pulse from doing damage there are a couple things you can do. First and most important, if possible, try to separate what you are welding from the vehicle. Second, connect welder ground as close to the area being welded as possible. Third, if available use an anti-zap or surge protector near welding site. Anything else is a pure crap shoot! That pulse seems unpredictable in nature! You can weld all your life without a problem, or the first time you weld something on your vehicle you put your PCM and other sensitive equipment through a severe electronic fire storm.
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Posting Guru
Joined: Apr 2010
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From: South Shore, MA
I'm with everyone else - I don't think the MIG work caused the failure. I just recently made some repairs on my truck via MIG. I was in a hurry. Left both batteries hooked up. I know better. 
So far so good.
So far so good.
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Fleet Mechanic
Joined: Mar 2009
Posts: 1,856
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From: Sacramento Delta, CA
When my van was delivered to Sacto. by the 4x4 converter, I jumped in and excitedly turned the key only to see the instrument cluster fail and also the alternator fail. The conversion required welding a cross-member for the transfer case.
FYI, yes Ford warns that welding on your vehicle can cause these kind of problems. See attached. I also personally believe that it was not a coincidence that the alternator simultaneously failed, but I have no proof of that.
FYI, yes Ford warns that welding on your vehicle can cause these kind of problems. See attached. I also personally believe that it was not a coincidence that the alternator simultaneously failed, but I have no proof of that.
i ain't rite
Joined: Mar 2005
Posts: 65,507
Likes: 5,565
From: Marlboro Mental Hospital.
i use one of these: Anti-zap Auto Surge Protector | OTC Tools
whenever welding on a vehicle.
i have had 3 alternators on the big trucks burn out after someone did welding on them, and had a brand new one day old alternator on my 02 go up in smoke when one of the monkeys at the shop putting front springs welded a nut to a broken stud.
the replacement alternator cost the spring shop more than the spring replacement job was.
whenever welding on a vehicle.
i have had 3 alternators on the big trucks burn out after someone did welding on them, and had a brand new one day old alternator on my 02 go up in smoke when one of the monkeys at the shop putting front springs welded a nut to a broken stud.
the replacement alternator cost the spring shop more than the spring replacement job was.
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