Alternator Problems - won't stay put

[gbarrett]

As we pulled down our street at the end of our long vacation in the GW, we heard a loud ticking from under the hood. The alternator bolt had broken and was in the way of the fan. I replaced the bolt and put everything back together. This morning on my way to work, it happened again. I'll put it all back together later today - I took the wife's car. Here's the million dollar question: When the A/C compressor is running, the alternator "bounces" a bit. When the compressor is not engaged, everything looks as it should. Has this happened to you? Any ideas?

Thanks

Greg

[Bob Barry]

This has never happened to me, and I don't believe it should be happening to you.

Do you have a bracket bracing the rear of the alternator to the block, going to behind that long round tube spacer that the main pivot bolt passes through? Are you using a two-groove pulley? How is your belt tension? It's not unusual for the belt to oscillate, but the alternator should be braced well enough by the factory brackets to not be affected by that motion. It sounds like yours is not braced well enough, or the tension may be too tight, not giving the belts enough slack. With the two belts on the factory pulleys, you should have enough grip on the belts without having to tighten the snot out of them.

[bignblue]

That HAS happened to me, and it scared the cr*p out of me when I heard that fan banging into the bolt. It had snapped off, right at the level of the block--hellloo, Eazy-out!

I didn't have a bracket holidng the alt., so I went to a local speed shop and grabbed one (actually, Daniel and his buddy took me when they came down to buy my Chero). I cheated: I took the bracket off the Chero and hodge-podged it on the Wag, and used the speed shop bracket (really nothing more than a long, curved piece of metal) to hang the alt back on the Chero.

WIthout the bracket, the alternator's weight and the belt tension is totally focused on that bolt. The bolt itself is a high-grade piece, but it's right next to the exhaust manifold--it gets hot, and it gets brittle.

BTW...I think the speed shop bracket was for a Chrysler motor, if that helps. They're pretty generic.

[JINGA]

Yup, happened to me. And it wasn't the first time it had happened on this rig. The fan blades had dings in them that I could never explain, but after I had that bolt go into the fan, I knew what had done it.

By the time I got it all apart I found out that the PO had heli-coiled the bolt hole. I don't think it's doing a very good job in there and I can't thread the bolt in as far as it needs to go.One of these days I'll have to remove the helicoil and start over.

If yours is backing out again, maybe you don't have everything put back together the way you think you do. Maybe your hole is helicoiled too and you bottomed out giving you the right torque long before you have the needed depth.

Here's a webpage I made about my adventure.
http://www.geocities.com/wwwjeffdotcom/altbolt

HTH,
Jeff

[gbarrett]

I'm curious about the aforementioned bracket. On both of my GW's the top alternator bolt goes through a bracket which is bolted to the water pump, timing cover, and A/C compressor. The bottom alt bracket is a curved one much like the generic chrome ones at the speed shop. Both GW's look like the diagram in my Haynes manual. There isn't a heli-coil and I know the bolt is going in all the way as the first time it happened the bolt was sheared off even with the engine. I was able to retrieve all of it using an EZ-out on it.

Do I need to fabricate another bracket? Am I missing something?

Thanks,

Greg

[JINGA]

Well, I'll go out on a limb here.

If your parts are right and everything is put together correctly it leaves the question: Why would the bolt come out of its hole?

1) Incorrect torque? I'm sure you checked this.
2) Too much vibration? Maybe a bad motor mount or something else is giving too much vibration and letting this thing work its way out.
3) Something is wrong with the threads in the head. You probably would have noticed this.
4) The head is getting too hot, allowing too much expansion, the hole gets bigger and the bolt works its way out. Sounds like a Click-and-Clack answer, but maybe it's worth something.

Have you put a star-type lock washer on this bolt? That might help it resist the tendency to back out. In an extreme case maybe cross drilling the head and wire-wrapping the thing down might work.

BTW, I think the stock bolt is a grade 5. I couldn't find a grade 5 when I replaced mine and used a grade 8. The last one that broke was probably lower than grade 5 (2 or 3?). I heard somewhere that stainless bolts are roughly equivalent in "grade-characteristics" to a Grade 5. Didn't now what the guy meant, but filed that info for later evaluation.

Jeff

[gbarrett]

Let me go farther out on a limb. When I replaced the alternator pulley with a double pulley, I purchased a "matched pair" of belts from Advance Auto. The belts were a discount brand of sorts. When one belt is on, the vibration is not visible, but when two are installed, it bounces like a Lakers cheerleader. I am beginning to wonder if the belts are not truly matched or one is stretching more than the other or something along those lines.

Whatcha think?

[JINGA]

hmmm, right, you said you had that visible vibration right at the alternator.

Well alright, while we're out on limbs here, HOW is it vibrating? I mean, can you see it "bouncing" about some point? As if one bolt was tight but some other was loose? Also, are your fan nuts tightened down properly? That fan-pulley will wobble like a belly dancer if it isn't tightened down correctly. Maybe with the extra compressor load, pulling on that second belt, the load in the belt on that fan-pulley is just right to make it wobble.

I'm having a problem with my own accesories in that by the time I tighten the alt. belt to spec, I can see deflection in my other components. Something ain't right. One of these days I'll clear everything off the front of that engine and put it back together slowly, with new hardware.

Keep me posted on what you learn. This one has me intrigued.

Jeff

Oh, and if you're worried about the belts not being matched, how about switching them? You said one gives you no bouncing but two does. Try reversing their positions, try each separately. (That sounds like fun smile.gif )

[64Trvlr]

Is the alternator bouncing and moving around or are the belts vibrating and dancing? If the belts are different lengths that will happen. Did you measure the belts to see if they're EXACTLY the same? Close doesn't count here.
:cool:

[coach-frank]

Read my message about the oil leak, same bolt so former owner put a homemade bolt with a nut welded on only it was a little too long and I think it pierced my timing cover

[tuckers89GW]

gbarett, This is a post showing the correct alt. bracket. I'm not sure if it goes back to '84, but that is it on my '89. Suppose its possible that the alt would twist just enough to loosen the bolt allowing it to work out without the back brace to the alt.? http://www.ifsja.org/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=2&t=004846

[ August 10, 2001: Message edited by: tuckers89GW ]

[porchpiggy]

My 88 GW has another small (about 4inch) bracket that runs from the water pump area over to the back side of the alternator, sandwiched between the long barrel bushing and the back side of the alternator top hole. This bracket has a slight "Z" curve to it and appears to be a brace to that long alt bolt, about half way down the length of it. I have discovered that this bracket is sometimes overlooked when re-installing. I failed to re-install it and noticed my pulley's did not line up by about 1/4 inch (the thickness of the bracket), plus I had the bracket left over. It took me a while to figure it out, because it sits back in a ways, not real noticeable. I found at least two other people that ran into this, one of them did not have the bracket prob becuase a PO did not look long enough, or maybe not all wag's have it. I know it has been found on a 72 wag, an 88 GW, and a 78 Chero. I have not been able to find a picture of it in my Haynes man. I have notice that in the several threads on alt bolt breaking, there does not seem to be mention of this little bracket, and I can see where the long alt bolt with out any other bracing could snap fairly easy. :(