Broken Alternator bolt/Cyl head


Well-known member
Mar 25, 2008
...on my 69 502...finally fixed this last Friday...tedious job using an angle air drill to drill hole in broken bolt....extracted piece ok....went to run tap,and it did not go in deep enough...checked bolt hole with small mirror/light,and there was another piece from a broke bolt still in there..:shocking:
Extracted it,and figure PO just left it and used shorter bolt...???
No question both pieces are two different bolts...


First piece...note taper (Threads) at end...

Bolt broke here...

2nd piece...sure glad I checked OTHER HEAD TO CONFIRM DEPTH FOR TAP..


Marked bolt with red paint to monitor far,so good...ran the crap out of the 69 yesterday...

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Which is why I use RTV for thread coating on every bolt, miss NONE....I"m lazy, too damn lazy to fight that crap next time round....
I was gonna suggest the grade 8 bolt for a replacement. Good choice! :thumbs:

Wuz thinking air craft bolts...(125,000 tensile strength)...but was worried I'd rip the head off the block....:lol:

I hoping the fact that the 2nd piece was the issue....talked to some C3 502 guys,and some have broke that same bolt...I think it backs out over time.(alum head expanding/contracting)..then load from Alt belt hammers bolt breaking I;m checking that sucker for tightness frequently...:banghead:
If you're worried about that bolt giving up, stop by your local Caterpillar dealer and get one. Those are some tough bolts. And then go by Aircraft Spruce (Corona?) and get a tube of "Inspectors' Lacquer", also known as "Torque Seal". Little tube like loctite, but goes on the outside like your red paint, but if the bolt moves it falls off. Kind of a tamper resistant indicator..:bomb:
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