tek-nic

Broken Bolt Woes - Unable To Tension Alternator

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So I was driving down the road today when I heard and felt a clunk. No power loss, and the motor seemed to be running fine... so I kept going. After about a minute, I notice my temps are climbing - and decide to pull over. 

Sure enough... my belt is completely loose. The alternator is just hanging on the hinge point. 
After a little poking around, it looks like the bolt which holds the alternator tensioning bracket to the car has broken off clean. Fuuuuuudge.

 

I limped the car home carefully after letting it cool off for an hour. 

Has anyone had this happen? Should I plan on removing the timing cover to get at that bolt?

As it stands right now, I don't think I will have a lot of luck with a bolt extractor... even with the radiator out, there isn't a lot of room to work there from what I can see. 

 

Any help is greatly appreciated. Sorry I don't have any pics of this at the moment... but I'm sure I will take some soon. 

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You're on the right track.  Try to do the extraction after removing the radiator, but getting a straight shot at the bolt is difficult with the timing chain cover in the car.

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According to his profile his car is a "1970 2002. It's a base model, with absolutely zero optional equipment."

 

Bob Napier

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This just happened to me. My quick fix is a bracket from the alternator to the block. Mine is a modified bracket from a clifford alarm siren, but if i didn't have that, i would have used steel stock from any hardware store. Bend in a vice, drill holes, then bolt it up. Make the alt side hole oblong so you have some adjustment. Use locking washers to keep it in place. Good luck!

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Thanks everyone - and yes, Bob is right... 1970 base with zero options. 

So the question is this... how long is the bolt which secures the alternator slide arm to the motor/timing cover supposed to be?

I took it apart today, and it looks like the bolt either backed itself out while going down the road - or it snapped off inside the timing cover. 

 

Does this bolt go all the way through the cover and into the block, or does it only thread into the timing cover? 

Any help is greatly appreciated!

 

Here's a picture of the hole in question, from the front - after removing grill parts and the radiator.

1782139_10153944980295456_90047537288269

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I tried ordering the bolt from my local BMW dealer, and they weren't sure which one it actually is. 

If someone has a motor sitting to the side that could check this, it would be awesome. 

 

The diagrams make me think it is bolt number 7, which is a m6x35.... but I really don't know for certain. 

Thanks again for all the help. 

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No. 6 looks right to me.  Your local auto parts (or home depot or loews, etc) will have a selection of metric bolts .... seems like a good time to go get a few of varying lengths to add to your stockpile.

 

Cheers,

 

Carl

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(edited)

It's not shown explicitly on that drawing.  If it's the one I'm thinking of, it's actually

an M8x 20 or so, and it just goes into that boss, which doesn't go through.  1 in yellow on the pic below

 

However, to me, it looks like you're also missing another bolt that holds the cover on, 2 in yellow.

It'd be an M6x maybe 25 or 30.

 

Off to the hardware store for you!  Get a can of degreaser, too, while you're there.  It's theraputic...

 

And yes, I've had that come loose on me, too- did a head in on a track day...

 

hth

 

t

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Edited by TobyB

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