j.squared

The bolt labeled #13 in the attached picture and the link below sheared off. This is the second time this has happened in 4 months. Anyone have any ideas why this is happening? The alternator belt was changed in Dec 2009 and the bolt first snapped off in Aug of 2013. Last night, about 2k miles later, the bolt has snapped off again. The belt doesn't make any noise and I don't believe I tightened it too much.


Any help is appreciated.

http://www.hondaautomotiveparts.com/...UNTING+BRACKET

j.squared

I should have said this: The car is a 2003 Honda Civic EX with about 148k miles

ezone

First, the mechanics' credo:
"Too loose is too loose, and too tight can be too loose too."
Did that make sense?
Can that apply to your situation?


What was that bolt torqued to?
What is the torque spec for that bolt?

Not the original alternator?? Alt may have a mis-machined or bent ear causing the bolt to not be exactly perpendicular to the bracket?

IDK, I can't see what happened there myself ....and I can only guess.

j.squared

Good question. I installed the replacement bolt. It wasn't over torqued. I followed the specs in the Hanes manual.

The alternator is orginal and hasn't been removed from the car. As far as I can tell the bolt was perpindicular when I installed it 2 months ago.

Are there more than two bolts holding the alternator on? As far as I can tell there are only 2. They are both present and tight. If the alternator was missing one bolt then it could be possible for the adjuster bolt to be supporting too much force which could shear it off.

ezone

Factory bolt or general purpose replacement bolt from a bulk bin?
Torque spec was.....?

(Who am I kidding? I use an air impact gun on them with no problems.....but I don't go apeshit on it, I maintain some control over how tight it gets.)

Erm...... your car is waaay overdue for a timing belt then. The alt has to come off to do that job.


Only 2 directly attached to the alt, plus the adjuster part that goes on the smaller bolt (#8 and #12 in your parts pic)
Is that adjuster part mangled in some way that would not let the head of the bolt seat flat?

Did the broken bolt snap off or was it sheared off? Or did it fall out? Does the broken part spin right out, no thread damage? How close to the alt does it break?
Got a close up pic of the end of the broken part, still in the ear of the alt?


IDK....I'd put it all back together again, because it's gotta go back together again.

j.squared

I've never done a timing belt job; I didn't realize the alternator has to come off in order to replace the timing belt. It had the timing belt changed about 50k miles ago.

I'll take a pic and check the adjuster tomorrow when it is light out and not freakin' freezing. :-)

The bolt was sheared off clean. It is sheared off between the alternator and part #7. That is to say if I remove part #7, I believe I can grab one thread on the remainder of part #13 and remove it from the alternator without an extractor kit.

ezone

Other half of the bolt is just gone then? I'm trying to figure out how close the break is to where the threads start on the shank of the bolt.

Kinda sounds like it was overtightened at the moment.

drhawkinz

If you have enough room to get a dremel in there you can try cutting a slot in the end of the bolt and then use a flathead screw driver to back it out. There's different grades of bolts which have different strengths. If you take the bolt to a hardware store and get a higher grade bolt then it should be less resistant to shearing off. Grade 8 is the strongest, I did a lower project on an old ranger and used grade 8 bolts to hold leaf hangers back to the frame and it held up great.

But I have no idea what would be causing that much stress on the bolt. I would almost think the belt is too tight but it's hard to say.

ezone

This hardware isn't using any SAE grades, this is all metric.




No matter, I think most of the hardware on the car is 8.8 fasteners, unless in a high stress area.




Can't be caused by the belt.
Bolt maybe?

Cutting a slot in the bolt is a great idea!

j.squared

I forgot to mention that the adjuster bolt is OEM. It is a bit of a specialized part so I just went ahead and spent a couple bucks to get the OEM part.

I doubt it was overtightened because I used a torque wrench on it and used the recommended torque setting from the Haynes manual. I'll look in the morning at the manual to see what they recommend. What torque should it be?

ezone

Bolts that use a 14mm socket: 33 ft/lb

Bolt that uses a 12mm socket: 17 ft/lb



EDIT: Pic removed, Damn GIS, wrong year pic

drhawkinz

I just had to adjust the belt tension on my sisters Altima to fix a squeal and the apparatus looks pretty similar. You loosen bolt #13 and then adjust bolt #12 to get the right tension. I noticed with hers when you'd turn the wheel it would squeal more so I'm assuming the power steering and AC would put more tension on the belt. I would imagine that would kind of tug on the alternator and put more stress on bolt #13.

I guess you could put the new bolt on and then mark the bracket (part #7 it looks like) with a sharpy or something and then if it breaks again look and see where the bolt is in regards to your mark.

I just picked up my Civic about a month ago so I haven't had to do much work to it yet ... Knock on wood.

j.squared

Ok. I fixed the car. :-) Not as cold out as I thought it would be.

The bolt was sheared off flush with the alternator. It was loose so I was able to get it out with my thumb pressed on the bolt and turning counter-clockwise. I thought I was going to have to get out the extractor kit. I was very happy when it came out without the kit.

None of the parts looked bent or caddywampus. The alternator looked to be mounted properly.

EZ - The other piece of the bolt is definitely gone. I heard it drop out and clang in the enginer compartment when the battery light came on.

I included a pic of the remainder of the bolt that broke and the new bolt next to each other to get an idea of where it failed.

ezone

Bolt looks like a clean break all the way through.
I'm going to guess it was overtightened. I really don't have any other guess at the moment- LOL

But I'm also going to guess that the top alt bolt is probably not tight enough. When it is properly tightened, it should take a hell of a lot of effort to move the alternator, it shouldn't just flop and let the belt be loose.

That top bolt should grip so hard you would nearly snap the adjuster bolt if you tried to adjust without loosening the top bolt first. Make sense?

j.squared

EZ - I did tighten the top bolt. Thanks! I made sure not to over tighten the adjuster bolt this time. I buttoned it all back up. Thanks for your help and insight; I appreciate it.

Dr. H - I appreciate your help too! Thanks for the tip with the dremel; I am sure it will come in handy sooner or later.

j.squared

EZ - had the same problem again. Alternator adjuster bolt is sheared off. The top alternator bolt is still tightened. The root cause is this: the top alternator bolt, even when completely tightened at 33 ft-lbs, is not holding the alternator in place. The adjuster bolt is the only thing holding the alternator up. Any ideas on how to fix this? I Don't want to over tighten the top bolt.

ezone

What's the chances of either of the stamped steel brackets being out of square?
Is the bolt is snapping off because it is clamping at an angle?

If it isn't that, and the hole in the alt is squared up right, there shouldn't be a problem there. That leaves overtightening that bolt?

What are you torquing them with?


I can't tell you what I tighten the alt bolts to. Tight enough, not too loose LOL.

j.squared

The bracket is straight. The issue is that when the top alternator bolt is fully tightened the alternator still pivots up and down. This is the issue.

I am using a torque wrench to tighten the bolts. The top alternator bolt is an M10 so I tighten it to within 30-40 ft-lbs which is the spec on an M10. Even when tightened to 50 ft-lbs the alternator still moves on the pivot.

I tightened the alternator adjustor bolt to 18 ft-lbs because it is an M8 bolt and spec is 14 to 21 ft-lbs.

ezone

Then it would seem to me that your small bolt is being overtightened IMO.
SOMEthing is making it shear off, what else have you got?







Is the long adjustment bolt and its bracket in place (#8 and #12 in the parts pic in the first post)?
This combination is supposed to be used to adjust the tension on the belt, then you lock it in place with the bolt #13, then you tighten the big bolt.
The bolts 12 and 13 might be thought of as "sharing the load" of belt tension and clamping the alt ear down.
The big bolt isn't designed to keep the alternator from moving, it isn't supposed to take the place of the other hardware. I'm just saying that when it's tight, that alternator is darn tough to move. There should be significant resistance to pivoting on that bolt.

It also has to ground the alt frame to the block. Well, all of the hardware is supposed to do that.

It CAN move, but it should not move easily. It might let the belt go slack if the small bolt is gone, but it should be tight enough to not let the alternator fall down completely.
It should take a lot of effort to move the alt once the big bolt is tightened.
(When I do a timing belt job, I zip the 2 bolts out of the slotted bracket and remove it before I loosen the top alt bolt. The alt usually stays put until I loosen that big bolt.)

The sleeve that is pressed into the end of the bracket attached to the block, is it seized or something? As you tighten the long bolt, that sleeve should move inward to meet the alt ear.


Is your torque wrench not accurate?
Ex: a 1/2" drive click type would not be very accurate at very low ranges.
I don't think I completely trust my 3/8" drive under about 20ft/lb.
Clickers are usually most accurate in the middle of their range, less accurate at the ends.

j.squared

When I loosen the alternator adjuster bolt the alternator "flops" down. It doesn't stay in place at all. The top bolt is very tight and doesn't easily loosen. It takes a good bit of force to loosen the bolt and I am not even sure if I can get that bolt out. It is at least partially seized. Can you remove the alternator bracket (#1 in the diagram) without removing the top alternator bolt?

I only tightened the alternator adjustor bolt with a 1/4" drive to ensure it wasn't over tightened. Then I checked it with my torque wrench. It is possible that the torque wrench is inaccurate, however, I would be surprised if it was an over-torque issue because I was overly aware of not over tightening it and the top bolt isn't sharing any of the load.

ezone

Well that would explain why your torque wrench says the bolt was tight, yet there isn't sufficient clamping force applied to the alternator.
The torque wrench didn't lie, but the threads did.
Better fix that.
I've never tried, I always have the alternator off when I take the bracket off.

Gotta take the engine mount loose so you can jack up the engine to get that long bolt out.


But what if you are a gorilla?

I can get stuff quite a bit tighter than 18 ft-lb using some of my 1/4" drive stuff if I really try, and I'm no gorilla.


Or being used incorrectly?

You need to start with the bolt semi-loose, then bring it up to the desired torque using the torque wrench.

It takes more force to start a bolt moving once it stops turning (breakaway torque), so you need to keep it moving until it reaches desired torque.
(Ever try to remove a crank pulley bolt from a Honda? Breakaway torque is far higher than the original tightening torque.)

If you only check it after tightening by hand, it could have really been tightened to anything over and above your torque wrench setting.

The object being checked has to move as you tighten it, and you have to stop at the desired tightness.



To an extreme:
I could use my clicker torque wrench set to 17 ft-lb, and put it on a lugnut and it would click.
But that doesn't mean the lugnut is 17 ft-lb.
The lugnut is really at 140 ft-lb.


I see guys all the time using an air impact to tighten lugnuts.
THEN they go over each with the torque wrench set to the spec, and it clicks every time.
They can't comprehend that the lugnuts are far too tight.


I also watched a kid use a beam type torque wrench as if it were a breaker bar. I first noticed this when he was tightening an an oil drainplug of all things.
He had no clue how to use it properly.
Watched the same kid borrow a click type torque wrench to do wheels: set it to spec, then put it on the first lugnut and leaned on it, it went CLICK, and the kid kept going on that lugnut for another quarter turn.
Kid was gone soon after that.

j.squared

Any suggestions on the best/easiest way to do this? I tried to take the bolt out but it will not come all the way out before it seizes up. It comes out about a 1/4" before it is completely seized up. It does go back in though.

BlueEM2

iTrader: (1)

Are you over tightening the belt? If the top bolt is not holding and your severely over tightening the belt I can see it snapping that little bolt pretty easily.

j.squared

I don't believe I am. I checked the tension by seeing how much play was in belt. I will double check this time. It is possible that I over tightened it. Is the small alternator adjustment bolt able to withstand that much force without the support of the top alternator bolt?

ezone

Not really.
Torch?
Sounds like threads have galled and all the threads will just be ruined by the time you get it apart no matter what.

You might try taking the bracket off....
Pull valve cover and timing covers
Pull PS pump up (and reservoir) and lay it up toward the intake area out of the way,
remove pump bracket to make more room
rock alternator up as far as possible
remove 5 bolts holding the alt bracket to the engine block
Remove alt and bracket as a unit, carry to work bench,

then you can try to get it apart.