evan98xj

hey guys i have a problem with the bolt and washer that holds the harmonic balancer onto the motor backing itself out. It all started on tuesday, its backing itself out to where its not applying pressure to the hb therefore causing none of the pulleys to turn. I tigtened it with everything i had and since then its backed itself out 3 more times, twice today and once yesterday. Im completly stumped and need a few opinions or has anyone else had this problem? Any help is greatly appreciated, thanks in advanvce. Evan

1976Mustang

Thread locking glue.

evan98xj

i was thinking that too, but would it make that big of a difference?

1976Mustang

Get strong enough stuff yeah, it should hold.

F1Addict

I agree that thread-lock would help but when you say it's loosening up to the point that your pulleys aren't turning... This likely means that you've sheared the keyway. Someone else can correct me if I'm wrong but your HB should never free-spin on the crank. Ever.

EDIT: Just read more carefully, it's not spinning on the shaft, just not contacting the belt. Sounds like a job for thread lock and a breaker bar.

DFlintstone

X2, shouldn't spin. The key is missing or sheared. That's also why it's loosening up I would guess.

evan98xj

There's no keyway on this hb

F1Addict

I'm not knowledgeable enough on the '98 to speak intelligently about it but I've never seen an HB without a key.

That said, I've never seen a '98 HB. Someone more familiar will have to volunteer their ideas.

tgordon

Something ain't right. I had a **** of a time replacing mine, had to use the pulley puller to get the old one off. Loosen the belt and take the HB completely off and inspect it carefully. There might be damage to the center bushing causing it to wobble and backing out the bolt. I would think for it to vibrate enough to loosen the bolt, it must not be balancing very well. I am just a DIY guy, no tech by any means. Please correct me if I am completely wrong here. The something that ain't right could be me.

Turbo X_J

?
I have yet to see one without, take a pic(s) so we are all on the same page.

F1Addict

My understanding of Evan's problem is that the harmonic balancer is turning correctly, with the crank, but that it's backing off the shaft enough due to the bolt loosening that it's no longer putting enough tension on the belt to spin the rest of the accessory pulleys.

I'm still concerned about the apparent lack of a key, that doesn't sound right to me. Without the key to hold it in place, the harmonic balancer would be allowed to place spinning forces on the bolt that holds it on and would certainly explain why it's loosening.

RTorrez1

I have never seen a harmonic balancer with out a key. That's what keep it lined up. I hope that it didn't screw up the crank while it was free wheeling.

Kwint

Pull the balancer and inspect it to make sure it's not cracked at the key way machine grove and inspect the crank key way grove as well , replace the key way , May have to replace the balancer , they can go bad and I have seen them cracked as well . Use the yellow or purple loc-tite (spairingly) on re assembly . On my 2nd one on the MJ

evan98xj

Is the keyway usually on the front of the hb or on the back of it? Looking at it from the front i see no slot for a key way, just the threads for the bolt and the fitment for the washer

Carl48

Just replaced my harmonic balancer last week...there was a woodruff key. Also, it is a tight .001" interference fit ...needed a special tool to press it on. The crank center bolt is a 1/2"-20 torqued to 80 ft-lbs...if the bolt is coming out and the balancer is spinning, something is really fubared...pull the balancer and do a thorough inspection.