Alternator Bolt / Engine Block Options

[hokiebird17]

Earlier this year I shredded 2 serpentine belts before realizing my alternator bolt was sheared off in/at the block (2007 ZR6). I replaced the tensioner, idler and raw water pulley prior to this realization. After getting the rest of the bolt out, I needed to rethread the block. This didn't go completely as planned as my EZ Lok thread insert had a tiny bit of play after inserting & a 3 day cure. In order to fix this, the block will need to be filled & rewelded as there is no room left to bore a larger hole.

Wanting to get feedback on options I was presented from dealer.

FYI im the 3rd owner & the original owner was from Miami, boat was exposed to salt for 2-3 years.

1. Remove motor, remove cylinder head & send offsite for repair
2. Remove motor & replace long block
3. (My idea/question) If above are not much difference in $ - remove & replace with rebuilt engine

Thoughts on other options?

[NautiqueJeff]

Can't they remove the head with the engine in the boat? Not sure why it would need to come out for that.

[hokiebird17]

A couple years late....Good news + 2 years w/o issue ... a quick & cheap DIY fix thanks to knowledgeable friends

Yes, we were able to remove the head & thread insert. Ironically there was still more bolt in the block that we backed out. We felt there was enough usable thread so we fabricated a bracket to brace the bolt. It wont win any beauty pageants but has done its job for 2+ years / 100+ hours.

[jkallen21]

I have the 06 ZR6 and reading stories on this forum (perhaps it was even your story), I proactively had the mechanic swap the bolts. I ordered them from Nautiqueparts and had it done as part of winterization. I'm glad yours worked out. If anyone else reads this and has that engine - be proactive!

[Scooter G]

Ingenious, amazing what you can come up with when you lay awake all night. Good fix!
Also like jkallen21's proactive approach. Known problem, beat it to the punch.

[srock]

woah... the known problem is shearing the bolt holding that bracket or is that bracket the fix? Or is the bolt the one behind the alternator?

[hokiebird17]

We added a bracket for peace of mind given the state of my head/bolt hole.

The alternator/idler bolt hole was not 100% but was still usable after extracting the bolt & thread insert (pic attached). When we noticed the open bolt slot - we came up with the bracket idea vs sending head off OR buying one.

To Scooter G & jkallen21 's point - a simple bolt swap likely covers everyone. I was trying to salvage some Plan B/C/D work when my thread insert didnt pan out.

Biggest learning from me on this - IF ANYONE HAS A BOLT SHEAR OFF - TAKE OFF THE HEAD FOR EXTRACTION & REPAIR WORK

[srock]

Thanks for the marked up picture. If it is an issue I should be placing a drop of penetrating fluid every so often until I make the change. Is the bolt replacement of a different grade?

[hokiebird17]

Yes, a 10.9 vs 8.8

98446070 in the engine parts manual is what sheared in the head.

I replaced with below, the bolt that came out was an 8.8 grade
M10-1.5X70mm Gr10.9

[Scooter G]

Fantastic write up, very detailed, thanks for taking the time.