Busted Alternator Bolt

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C10_Blackie

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Hi all. Sorry about the length of the post but I didn't take any time to take photos while this was happening. I have a 1981 C10 with what i think is a Goodwrench crate 350 motor of unknown age and origin. I'm not an experienced or knowledgeable mechanic. I bought the truck in December. I haven't been able to drive it much as I got COVID right after buying it and took me a while to recover, but I've taken it on three or four short trips so far in order to shake it out and get used to it.

While on a short trip today, I started to hear a clanging sound that started out faint but quickly got way worse and then stayed loud and constant. I pulled off the road, left the engine running, popped the hood and found that what I'm gong to call the alternator pivot bolt had worked itself out and was impacting the cooling fan. I shut off the engine and tried to screw it back in place thinking that it had just come loose but it became apparent that it had sheared off somewhere back in there. I didn't want to back it all the way out so I just pushed it back in place and limped the mile back home only having to stop and reset it once.

I pulled the alternator out when I got home since I had been hoping to find some engine stamp numbers back there (didn't, unfortunately) and found that the bolt had sheared off in the effing engine block. I noticed that the bolt goes through a bracket connected to the block, then through the alternator, then through a sleeve that is on a bracket attached to the alternator, and then into the the block. So I pulled the bracket off that was attached to the alternator and used a shorter bolt to just attach the alternator to just that one bracket and put everything back together. After a short half mile drive, the belt tension didn't seem to loosen and everything looks good still.

So first question is that I already had an appointment with a good shop about 25 miles away (mostly highway) next Monday to have the truck checked out. Is there any reason I shouldn't drive it there as-is if it looks like the belt tension is holding?

Secondly, what would make a bolt that size shear off like that? Is there some possible root cause that I should be concerned about, like maybe the motor is moving around too much relative to the fan pulley?

Thanks.
 

Ricko1966

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I'd be interested in seeing your alternator brackets. All of them. I think you may have mismatched brackets. If you have a fully charged battery and the power steering belt is still spinning g the fan and water pump your truck will drive 25 miles without an alternator at all.
 

C10_Blackie

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I'd be interested in seeing your alternator brackets. All of them. I think you may have mismatched brackets. If you have a fully charged battery and the power steering belt is still spinning g the fan and water pump your truck will drive 25 miles without an alternator at all.
I’ll take some pics tomorrow. Thanks.
 

RustyPile

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I wouldn't chance driving that far without an alternator, too much risk of being stranded with a dead battery.. Disconnect one of the battery cables and remove the brackets, alternator, and that sleeve.. That long bolt doesn't bottom out in the hole so the piece should unscrew easy enough.. You might have to use a sharp tool to pick at the piece to make it turn... A grade 5 or better hardware bolt is a suitable replacement. BTW, the bolt screws into the head, not the block.
 

Ricko1966

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Of coarse if you can fix it where you are and with your skills,then fix it. If not,what you have is working and probably will not fail in 25 miles,I think I understand how you fixed it,making my previous post moot. If you are worried and have to drive, take a second battery with you just in case. Personally only because of the circumstances I was dealt,I drove from Enid Oklahoma to O.P. Kansas on 2 batteries no lights,no radio,no accessories. Also drove from LaCygne Kansas To Kansas City on 1 battery,fully charged it before I left,1 start no lights,no radio,no accessories,bought an alternator in Kansas City,changed it in the parking lot.Maybe I am just very lucky. Wouldn't have been my first choice in either instance,but I did what I had to do.
 
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GTX63

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For comparison, late model trucks are notorious for bolts shearing off due to rust and poor metal composition, ie LS exhaust manifold bolts.
If a bolt shears off on an old squarebody truck motor, it was likely cross-threaded and the guy doing the cross threading knew to stop tightening just as he felt the bolt starting to give. Would I drive it 25 miles for repairs if I had little mechanical experience? With a spare battery, a jump pack, jumper cables and tools to swap things out, probably.
 

C10_Blackie

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Thanks for all the great responses! Here's what I did (pics attached). You can see the new bolt, washers and nuts I installed in the wide and close-up shots at the bottom of the alternator to the right of that interestingly-placed (at least to me) gas filter. So I had pulled off the bracket and sleeve that was attached to the alternator and just attached a shorter bolt with a nut and some washers. What's harder to see is that there is a bracket that is attached to the head that you can see part of right under the nut cap and washers. The other picture is the sheared off bolt and the sleeved bracket that I removed from the alternator.

The busted off piece still sitting in the head (not the block -got it) is recessed a good 16th of an inch in there. I hit it with penetrating oil but I don't think it is going anywhere just using my skill set.

On the bright side, I'm holding the three best tools a person could have for the 25-mile trip to the shop: plenty of spare time, a wife driving chase in a dependable car and our AAA-Plus membership with a 100-mile towing limit. (And yes, I could have just had it towed but I'd just much rather not do that on principle.)
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DoubleDingo

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That shorter bolt isn't doing anything. That spacer looks like one for an old engine with different type of alternator brackets. Charging your battery and not running any accessories will get you the 25 miles you need to go to get to the shop.
 

Ricko1966

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Yep,that's how I thought you repaired it,not good long term but it'll get you to the shop. Have them bend a steel line for your fuel line. If they can't couple it to the Holley line use 3 inches of rubber as a coupler. A pin hole in a rubber line after the fuel pump is a squirter gun spraying fuel on everything,some people have a problem but I've seen more than one engine fire as a result.
 

DoubleDingo

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For comparison, I drove my 1991 Jeep Cherokee with a new battery and bad alternator 180 miles. I was concerned the entire time, especially because a good portion of the drive is in the middle of nowhere, but I made it home with a few volts to spare before it shut down completely.
 
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C10_Blackie

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Yep,that's how I thought you repaired it,not good long term but it'll get you to the shop. Have them bend a steel line for your fuel line. If they can't couple it to the Holley line use 3 inches of rubber as a coupler. A pin hole in a rubber line after the fuel pump is a squirter gun spraying fuel on everything,some people have a problem but I've seen more than one engine fire as a result.
Yeah, what you said earlier gave me the impression that you understood what I did from the get-go and after a few more short test drives nothing has loosed up. Thanks also for confirming my suspicions that this isn't something I want to leave this way for too long.

I'm also with you on the fuel lines. Actually all the wire routing in there is horrible but especially the fuel lines. I mostly used to restore old air-cooled Volkswagens and engine fires were almost common because of this very thing. If the shop doesn't find any deal breakers and it officially becomes a long-term project, I'm planning on getting the transmission cooler, A/C and cruise control working again so eventually will need to get all the wire and hose routing settled in there. (@SirRobyn0, I hope you're taking notes...)
 

AuroraGirl

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spacer/bracket bolts to... alternator? and then long bolt through to the head. iirc....
 

AuroraGirl

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This is what i mean about bracket to alternator, then long bolt through the sleeve part
 

DoubleDingo

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This is what i mean about bracket to alternator, then long bolt through the sleeve part
Hmmm, mine have never had that, just a spacer that the bolt goes through.
 

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