i left my keys in my truck friday night with the switch on and killed my batteries. got someone to jump me off and everything was fine until this morning. the truck barely turned over and would not start. had to get someone to jump me off agin. the batteries had 12 volts in them before the jump dropping to 7 when turning the switch to start. the alternator was putiing out 14.2 volts after starting. while i was looking around under the hood i noticed what you see in the picture. it appears the bolt on the mounting braket has worked its way thru the mounting point on the alternator. this aint normal is it? does anyone elses look like this? i guess its time for a new one. i have never worn out an alternator in this way before.

Very unusual...

I've never seen anything like it. It didn't "wear through", since the parts aren't supposed to move against each other significantly. The only thing which comes to mind is a "break"... maybe something physically hung up. First guess would be in the alternator, second would be other driven devises on the belt. I once had a Suki Samurai that ate fan belts with annoying regularity. I was getting rid of it anyway but was convinced it had a bad alternator bearing or water pump.

i say worn thru because the threads on the bolt have cut grooves in metal of the case as it has passed thru it. i think you should be able to see them i this picture. ther are no grooves inside of the hole just the portion it passed thru.the lower inboard portion of the hole is folded down with grooves cut in it. evidently it has been going on for a long time. ill be interested in seeing if it has any core value now.

Definitely a new one for me! If they notice when you turn it in, that's definitely scrap - not a core....

that bolt has been loose for a long time the viberation of the motor has wore it throughas for a core it is scrap

I have had an alternator does this before! Carried it to a buddy he welded it up redrilled it, put a new bolt in an she's still running!!!

that bolt has been loose for a long time the viberation of the motor has wore it through as for a core it is scrap

the bolt was tight. i had to lean on it to break it loose. it did wear part of the bolt away. the casing of the alternator had to have a weak spot in it

Sometimes a bolt can be "tight" and yet not tight... A lot of alternator mounts have bushings & washers. Very odd failure.

I have had an alternator does this before! Carried it to a buddy he welded it up redrilled it, put a new bolt in an she's still running!!!

might have to try that and keep as a spare. really did not know you could weld to that metal case. what is it made of?

They're cast aluminum.

Sometimes a bolt can be "tight" and yet not tight... A lot of alternator mounts have bushings & washers. Very odd failure.

no bushing or washers. just abolt thru the mount, thru the alt, and into the bolt welded to the mount. i guess the hole in the alt could have been a little large and the engine vibration just slowly worked it thru.

Actually I just put it together... If you look at the pics you notice the mount is a metal that horseshoes over the aluminum ear of the alternator so if the bolt wasn't capable of squeezing the metal against the aluminum ear then the alternator could eventually vibrate and chew its way through the alternator. So you might check and see if you can get a good squeeze on the new one.

i had to reuse the old bolt so i tried not to overtighten it due to its condition. i am going to buy a new one today and will put the super torque on it. the mount is pretty stout. might try to get a thin washer in ther too. had the alt tested when i bought the new one and it tested fine. bought it at Auto Zone. reman by nippondenso $95. limited life time warranty. i figured with a name like nippon it wasnt made in china. but i would be wrong. of course it was the cheapest one i could find. iam a little broke these days.

Nippon Denso typical... All the alternators are china made.

Likely, the China made alternator boss is out of spec. First I'd try to shim with washers to get a squeeze on it. Some alternator mounts have a sleeve which slides in to adjust for variation in dimension. But doing that would be more work.

the bottom mount next to the engine had a sleeve just like the oe bosch. the top did not have one just like the bosch.the new mounted up just like the old one. i just checked the top mount around the boss and i cant slip a piece of paper in between them. when i get the new bolt i will put the super torque on it. then i will just keep an eye on it. the whole thing is kindly wierd:cookoo: if you know what i mean.

--- Update to the previous post...

Nippon Denso typical... All the alternators are china made.

my wife is of nippon heritage, but she was made in japan. she was 1 1/2 years old when they ran her out to the states:lmao:.

Stranger & Stranger... ??Scratching head??

edit[/edit

The original alternator did not do this. (presumably) At least you are paying attention. It will be interesting if this were to happen again.

further edit

I just looked at my truck. My thought is that the 2 sides of the steel bracket stamping are supposed to squeeze together to grip that aluminum boss on the alternator tightly. If the bolt was not threaded enough (perhaps a replacement when the alternator was replaced previously) or rusty or the welded on nut rusted / damaged might prevent the steel from squeezing although the bolt might be "tightened" to spec.

If this was my truck, I'd compare length, wirebrush / chase the bolt threads, maybe run a tap into the nut section, a drop of oil or NeverSeize, reassemble.

Russ