Broken alternator Bolt ZR6

[sstexan]

Well, my first outing was ruined by a broken alternator bolt. Everything started fine, idled for a good 20 minutes. Once, I got on plane, I heard a strange noise, you know the rest. My questions are:

1. It sure looks to me like one of the bolts had broken off long ago. I could not find the other part of the bolt. I am pretty sure I saw the other part a year or so ago and chuckled that it was just a spare bolt from manufacturing. Not so much the case anymore.

2. The alternator turns pretty freely by hand. Is it possible I have an issue with the alternator that caused it bind and create the friction to snap the bolt(s)?

3. How easy to do you guys think it will be to extract with an easy out? I want to do this myself, but I also don't want to screw the block up?

4. For $275 I can replace the alternator. I have a 2007 with 400 hours fresh water only. Since I have everything completely dismantled, should I just put a new one in?

Thanks, hopefully those bolts come right out, but my guess is this will take the better part of an evening.

Thanks,

sstexan

[Skidave]

Penetrating oil (lots of it), good drill bits and a good set of easy-outs. Maybe a torch for some heat applied carefully.

For what it's worth, if you have a trusted machine shop near by, get an estimate. Even a trusted car dealership. They can do the work, just worry about stains on your interior from them walking in and out.

[swankster]

You would have thought the belt would have gone before the bolt. I would agree with you the bolt probably went a while ago. The alternator is almost 10 year old. If it were me, I would take it to the shop and have them test it before I spent $275 on a new one.

[Laptom]

I had the same problem in my 2007 ZR6. Contacted PCM about it because in my opinion this is a design fault. Only 2 bolts holding this long bracket with a heavy alternator with a pulling belt. This is a recipe for failure. PCM admitted that the have seen more broken, but would not call it a design issue.

I countersink in the middle of the bolt a good dent in it. Drilled a small hole and reversed the bolt with the easy outs. I'm not sure if I heated it up. It took indeed a good evening, but it worked out fine. Bought some good bolts (10.9 steel) and fixed it by myself. Within a year the alternator died 😕.

Now after 5 years or so it still holding up ok.

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[sstexan]

Guys,

Thanks for all your help. I ended up getting both bolts out last night. The Easy-outs did not work, but slicing a groove with a dremel and then a large screwdriver got both of them out. Thanks again!

SSTEXAN

[Cadomin1]

Hi, I own a 2012 super air nautique with a PCM ZR 6.6L 409 HP engine. My serpentine belt broke the two bolts that support the alternator. Is this common? or could it be a problem of misalignment of the pulleys? Does the idle pulley of the picture looks right? or does this idle pulley is misalign with the alternator pulley creating to much tension and breaking the bolts? Thanks in advance

[wakemaker]

update

[docderwood]

I'm hoping to drill out the alternator bolt in mine tomorrow after it sheared off also. 2008 ZR6 390. This looks like a common design issue. Mine was causing the belt to slip off. That alignment looks odd....but maybe the groved pullye is supposed to be offset towards the alternator to pull belt to outer flange on idler? Mine is slightly different (idler has no flange).

On another note: What type of replacement bolt would you recommend? It's 3/8's I believe.

[tdc_worm]

Interesting. Shredded my serp belt two weekends ago. Went to install it last night....turns out you can't keep a serp belt on the accessories if the alternator is laying on the impeller housing pulley haha. Both bolts sheared.

Did anyone happen to catalog the size replacement bolts they used? Plan to try to coax mine out this weekend.

[sstexan]

Sorry, I do not remember the size. I took the old bolt (what was left of it) and took it to a speciality bolt store. As someone else mentioned, make sure you get a 10.9 or stronger bolt.

[sstexan]

For what its worth, my fix has worked for 3 years and 125 hours so far....

[tdc_worm]

Appreciate the feedback. As soon as I figure out the size Im headed to my fastener store ...

[ecoastkid]

Well I guess when I change my impeller this weekend I'm going to replace the bolts on mine with some 10.9 grade bolts. Why wait until I need to extract bolts....

[ecoastkid]

For future reference...here are the bolts from my 2007 220 with a zr6
the larger one is m10 - 1.5 x 110m . The smaller is m8 - 1.25 x70

Lowes only had the smaller one in 10.9 and I'd assume that's the one more likely to break so i replaced it.

I have no idea if there are marine grade bolts for this stuff but I'll Google that up later. This will do for the moment

[tdc_worm]

good feedback. there are, however, two m10 bolts that fix the bracket to the block. The longer m10 also attaches the alternator to the bracket. the shorter m10 only goes throught the bracket into the block.

Both M10s on mine were sheared.

For future reference...here are the bolts from my 2007 220 with a zr6
the larger one is m10 - 1.5 x 110m . The smaller is m8 - 1.25 x70

Lowes only had the smaller one in 10.9 and I'd assume that's the one more likely to break so i replaced it.

I have no idea if there are marine grade bolts for this stuff but I'll Google that up later. This will do for the moment