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bopp

Corroded / messed up alternator bolt - why did this happen?

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Friends, I have a '93 Legacy wagon with 230k. In early February I swapped my failing alternator with the '96 reman (see http://www.ultimatesubaru.org/forum/topic/142320-weird-electrical-pulsing-93-legacy-wagon/ for details).

 

Yesterday, I was driving home from work, and I could tell something was very goofy with the electrical system (started funny, delay/loss of power in acceleration, blinkers sounded weird). When I got home and shut off the engine, it would not restart - won't even turn over at all. This is the exact behavior I had recently when a squirrel chewed through my alternator wire - which I repaired. My assumption, therefore, was that my splice had come loose somehow, or some other wiring issue.

 

The two-wire connector is just fine...reading a little under 12V to the battery and also impedance is 0 to the battery. So that's not it.

 

However, the big two-wire socket connector on the top - weird stuff there. I just put this in a few months ago, and the nut and bolt are super corroded. I removed the nut and found that it had partially fused with the bolt - both are screwed up and I cannot get the nut to tighten down anymore. Appears the bolt may have to be replaced...if that's even possible...I'm going to get a free AAA tow to my mechanic on Monday morning.

 

The big question is: what would cause rapid corrosion and metal fusing on that connector?? Could it be related somehow to using a different alt than spec? A sign of a different electrical problem?

 

Also, could this possibly have anything to do with my latest squirrel problem? (see http://www.ultimatesubaru.org/forum/topic/146230-93-legacy-code-21-coolant-temperature-sensor/) (I have since added split tubing to EVERY exposed wire under the hood. Sigh.)

 

THANKS!!!

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The connection there was probably loose which created a lot of heat. Not talking hot to touch heat, I mean hot enough to make the nut and wire end glow. This would lead to a high oxidation rate befause the protective coating on the nut and stud would have burned.

 

Post a pic if you can.

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Even if not getting hot, loose bolts with current running through them can cause all kinds of weird oxidation effects.

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Photo below. You can see the corrosion on the nut and on the inside of the black rubber "boot".

 

Before I realized the nut and stud threads were messed up, I flipped the nut around and tried putting it back on...now it won't tighten nor come off. (Awesome.) So I cut the wire (since the spade connectors look trashed anyway), pulled the alt, and will take it somewhere tomorrow to see about getting the stud replaced. Anybody have any experience doing this?

 

 

alt.jpg

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Yeah, that cooked because the connection was loose.

The white stuff is from the rubber boot smoking.

The eyelets can usually be cleaned up with a wire brush or sand paper.

 

Are the threads on the stud trashed? Usually you can wire brush that and the threads will clean up fine. If not running a thread die on it should take care of it. The nut can be replaced with pretty much any metric 10mm nut.

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Cool, glad to have an explanation for this! Good lesson in tightening things down. The issue now is getting the nut off the stud, as it will neither tighten nor come loose...

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Oh... it won't come off the stud.

Use a screwdriver/small prybar to lift up on the bottom of the nut while you turn it with a socket. Pry up on the eyelet if you can't get under the nut. Make sure the battery is disconnected before you do that though.

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The small screwdriver as prybar was a great tip - nut came off almost immediately. Should have thought of that!

 

Now then, with a couple of retaining nuts removed, I was able to remove the stud assembly and get to the stud itself! (Somebody thought of this in the design process and made it easy.) So, I need a replacement for this thing below. The threads are totally messed up - it is not salvageable. Does this thing have a name? Who might have one?

 

Your help thus far and going forward is so very much appreciated!!

 

alt2.jpg

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Nice! Didnt know those could be removed that easy.

 

If I still had the dead alternator from my 95 I'd ship it to you.

 

I think you'll have to find an alternator rebuilder for a new one. Might get lucky searching google?

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Local alternator rebuilding shop pulled the stud out of an old alt and gave it to me for free - those guys are great (Morton Grove Auto Electric for anybody in North/West Chicagoland). Put it back in the car and it still won't start, so I'm off to AutoZone to get the battery charged - pretty sure I ran it down throughout this process. I'll update again... Thanks!!

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Alright, car is running! I took the battery to AutoZone for charging and it tested bad...I really hope they weren't lying to get me to buy a new battery...but I bit the bullet and got a new one. Battery reads 12.5v and when running it reads 14v showing good charge from the alt.

 

Thanks for all your help!

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In case this is useful for someone, the alt shop guys called this part the "extender" and said mine was a Hitachi, though he initially thought it was a Mitsubishi. So I needed a Hitachi extender.

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