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why my rebuilt alternator failed

tektic

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Joined
Dec 19, 2012
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1,499
Location
ronkonkoma, ny
Opened it up.


I soldered it back together and will bring it to have it tested tomorrow. All the diodes measured good brushes wer good bearings were good. Could that have really been all that it was?

This is the one that was draining my battery. I haven't taken The one out that failed on me yesterday. I hate replacing alternators in this car. I have to pull the headlight to get to the intercooler couplers and the power steering pump... Bullox.
 

tektic

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Joined
Dec 19, 2012
Messages
1,499
Location
ronkonkoma, ny
That's the positive leg for the charge cable. The solder completely broke free and it was just banging around when I opened it.
 

tektic

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Joined
Dec 19, 2012
Messages
1,499
Location
ronkonkoma, ny
So I had repaired the alternator above and had it checked at auto zone. It passed their tests. I pulled the alternator out of the Galant and dissected it to find the point of failure. to my surprise it was the same issue.



Also the screw in the top of this image backed itself out, and there was scratches and some fan contact inside the case.

Before I found this alternator died the same death I planed on putting the first one back in. Now I'm thinking there's an underlying issue. A friend from work Said it could be "chasing ground." I have a 6awg strap connecting the alt case to the chassis. I would think that would be enough ground or I just don't understand his prognosis. Please advise.
 

tektic

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Joined
Dec 19, 2012
Messages
1,499
Location
ronkonkoma, ny
I don't know if this is the best Idea... but under advisement from a friend I welded the metal terminal back together on the second failed alternator. If there's still a voltage drop somewhere in the charging line I think I'm just going to melt something else in the system.


This stuff was so light I burned right through it on the lowest setting. Looks like ass but there should be enough metal there certainly more than when I started. I'm going to clean it and fill in any gaps with solder.
 

thomcasey

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Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
Mitsu alternators like to pull air from the rear of it for cooling. That failure is common, especially when runing an exhaust without heat wrap/original heat shields. It sucks in the heat from the exhaust and melts the connection there to the regulator. I get good life out of mine by wrapping the downpipe so it isn't sucking in the hot air
 

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