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broken bolt 1993 alternator tensioner thread size/depth


Nov 15, 2017
broken bolt 1993 alternator tensioner to block thread size/depth

Anyone happen to know the thread size and depth of a b230 alternator tensioner bolt from a 1993 240? My bolt is broken. I drill it pretty much exactly on center and it wont come out. I don't want to bow up on the easy out and further for fear of breaking it and then having to drill out a super hardened easy out. So I feel like a helicoil is the way to go. I don't want to drill too far though and hit coolant.
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So I decided to drill just a hair of the threads out because the bolt broken below the level of the block and after I did that I used the craftsman micro easy outs(which bit better than a standard one) and the bolt came out. Now I just need to buy a new one
The parts catalog shows 2 different brackets and bolts for the alternator tensioner. -'91 uses 955304 and '91- uses 947760 which is a M8 flanged hex bolt 40mm long.
Looks like it is part number 955304 which is an m8x70

Went to Lowes and compared the removed bit plus the left over bolt along with a new bolt and it is in fact an m8-1.25x80. I bought an 80 and 85. If it'll tighten up with the 85 I'm going to use it. The amount of shoulder matched up perfectly as well. That said the reason why it broke was the previous owner had the accessory bushings in so that the whole assembly could slide forward. The only thing keeping the alternator in place was this one bolt. I just picked up the car last night.
Yup I messaged gsellstr to get some nice poly bushings in there. Ordered all new belts, oil separator/flametrap parts, timing kit, seals, motor mounts, and a bunch of lights that are out. Once I get those in I'll flush all of the fluids and start checking out the suspension.
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