loose crank pulley
 

few months back i had this noise from the engine and found out that the crank pulley was loose, after replacing the alternator and buying a new power steering pump, and a new water pump (both that i did not install yet) and CVF pulleys that i did install, i used blue locktite on the balancer pulley bolts all good noise gone, until i heard a noise again today thank God i checked today i saw daylight between the balancer and the pulley, all the bolts were loose i just tightend them up, i guess i should of taken them out and put more locktite on them but didn't, the cvf pulley came with allen bolts, why would these loosen up and should i have used the steel plate off the stock pulleys im thinking of getting new bolts and replacing them all or use studs any advice on this would be helpful

I have never ever had to Loctite pulley to balancer bolts in!
If it’s a used balancer then the bolt hole threads must have lost too much meat to rust over time.,

Something is up with that balancer!

probably 20 years old

Happened with my SFI Balancer, but never happened with stock Balancers.

So the bolts loosen and the Pulley holes oval-out.

I drilled 4 new holes and used Short Studs from modern junkyard waterpump Pulleys. Solved.

The same thing happened to me with my 69 GTO Conv. Heard a noise in the front of the motor thought it might be the water pump so I changed it. Still had the same noise. Checked the balancer and found the four bolts loose for the pulleys and the holes egged out. Bought a used balancer from Franks Pontiac parts, bought used pulley’s on EBay and the noise was gone.

loose crank pulley
 

well it happened again, i now have a stock balancer with 1 broken bolt in it, 1 destroyed CVF lower pulley, what gives, is my motor out of balance, the balancer looks good no issues can i get away with drilling new holes or get a stock one

Looks like the pulley is kinda wrecked. I had the same thing happen to my wife's 68 Firebird. Could hear this noise every time we started it, and I finally found it was the bolts that hold the pulley to balancer. I used blue loctite and was never a problem again. I used the blue loctite paste, not the liquid.
I sold a friend a complete engine and a year later he was in the process of pulling the engine out because of this strange noise. I meet with him and found the 4 bolts loose on the balance pulley. We loctite them in and has been fine since.
On our IA2 engine it have a 3 bolt ATI balancer. I used the stock steel pulley that I re-drilled for 3 hole mounting. It uses 3-3/8" bolts. I used the blue loctite paste on the Allen head bolts, and to date no issue. I keep an eye on them. Here could be another issue is that your bolts do not go the full length of the balance threads. I ordered specific length Allen head bolts for my balancer. You just have to watch the engine side of the balancer that the bolts do not protrude to far out the backside of the balancer. I found the longer bolt has more threaded area to apply blue lotite. Seemed to work for me.

If I were you I would go back to the steel pulley. Loctite them in and keep an eye on it. I have a friend who took his balancer to a machine shop and had the 5/16 bolts upgraded to 3/8" bolts. No issue after that. Use some grade 8 bolts in it also.

good advice
 

in my 68 when I shirch from NON AC to AC pulleys with factory blancer spacers
I questioned bolt depth. So I ran a test bolt in to measure depth and installed 4
new grade 8 with blue loctite that were longer. Also used factory spacer/retainer under
bolts on outside of balancer pulley.

No issues and belts lined up perfectly!!!!

Gerry

You do not want grade 8 bolts to hold the pulley on!

They do not stretch at the factory intended torque setting to provide the needed clamping power.

One thing I would do at this point would be to take the balancer off and look for the start of cracks in the keyway slot and look for signs of ware in this slot and on the keyway itself.

Rust pitting can also make for a non tight / poor fit of the balancer, and if it’s slapping around due to poor fit issues you will have to tack weld the pulley on to get it to hold long term!

Can you post up a picture of what the under head area of one of your bolts that are coming loose look like please.

Well, I didn't know that. I have used alot of grade 8 bolts on my 3 vehicle restorations. Maybe that's a different thing since it not a stretch situation. On my IA2 I found some Allen head bolt that had a very high tensile strength. Can you advise what a guy should use?
Thank you

The engine iam building now i have basically studded the crank pulley, quality old school allen head cap screws in from the back, had to chuck them up in a drill motor against a grinding wheel to radius under the head for the radius on back side of balancer so a sharp edge didnt dig into balancer, light hand torque with blue loctite let cure and i have grade 8 locking flanged nuts

the bolts are not going foreward and the nuts should stay tight

What I would suggest to the OP at this point if his keyway and key looks good would be to to first check that the bolts he is using do not have a shoulder that is too long and Is only minimally clamping down on the pulley.
Yes, there needs to be a shoulder to center the pulley, but not so much that it bottoms out on the face of the balancer.

If that is taking place then look for different bolt’s, or add a washer or two.

If the bolt holes themselves have slop, then no amount or type of Loctite will hold for long.

If this is thd case then I would drill and tap those loose holes for the next size up metric bolts to get back to a fresh starting point with brand new threads, and you could make these fine pitch threads also for better clamping power.

higher grade bolts still stretch just at a higher torque value
so you have to be cognitive of if any parts in a given situation can handle the extra torque or not
an aftermarket steel hub vrs stock cast iron or will a bolt dig into a pulley or not

if i ran a aluminum pulley i would spread the under head bolt load out with a thick wide hard washer possibly over top of the stock reinforce ring but i like steel pulleys myself

single alum pulleys can be purchased i wouldnt try to resurect a damaged one

it was probably flexing before and worked against the bolts the alum gave way creating a loose juncture be my guess from miles away looking at a postage stamp size pic ��

rotating and drilling new holes would make its flexability higher in my estimation

What I used. Thoughts?


https://www.grainger.ca/en/product/C...PK/p/EBP22TR34

I'll also throw this out there... When I got my aluminum pulley set from RARE, I asked the owner if I still needed to use the factory steel ring plate and he said no. I'm assuming the same would be true of the aluminum CVF pulley. The aluminum pulleys are thicker than the factory steel pulleys, so that makes sense.

I've never had an issue with the stock pulley setup and using the stock thin ring under the bolts to spread the load.

i did not use the ring on the aluminum pulley and used the bolts supplied with a washer i should of used the stock bots so next is to get the bolt out look for and damage to the balancer and get new pulley with new ring and bolts and loctite it in question is is why this happened the first place

balancer
 

ok definitely should of used better washers and the stock bolts im thinking of putting new bolts in from the back with red loctite and getting a new steel pulley the balancer looks good and the crank as well just not 100% sure why this is happening is it possible that something is out of balance i have no vibrations, also thinking about drilling out to 3/8" as well

Good that you posted pictures because in that front shot you can see that the elastomer that bonds your center hub to your outer hub is shot.

You can clearly see that it has started to shift and in the rear photo you can see that it's starting to split.

This is making for you bolts backing off even though your not feeling a vibration.

That balancer's outer hub is on the way to flying off on you!