BHJ + Broken crank pulley bolts ..

Ddubb

Registered User
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Well .. the last time my crank pulley started wobbling, the bolts were tightened up a bit. Now it started making that knocking sound again, so I went to pull the crank pulley off .. three of the four bolts were broken. So I pulled the HB off also, the BHJ bolts are only tapped down to the hub - I remember reading about this in other threads. And my crank pulley looks like its been wearing in where the bolts mount.

I am going to take the BHJ to a shop to see if they can extract the bolt remains .. I am just wondering about putting the crankshaft pulley back on - should I weld some washers on where the bolts were digging into the balancer, use shorter bolts .. or have the machine shop drill the threads a little further down ( would that be structurally bad for the BHJ hub ?? ) ... or just pick up a different crankshaft pulley in better condition ??

Thanks for any input / advice ..


- Dan
 
Thanks .. I tried to search but I didnt think to use Shorter bolts in the search terms.

I bought the BHJ used and I dont recall reading anywhere about using shorter bolts, but that does make sense now ...



- Dan
 
I have heard of others not having the shorter bolts listed in the instructions.
I guess I was one of the lucky ones who did.
 
The bolts may not be fun to remove because the last couple threads are probably jammed into the non-threaded portion of the bottom of the hole which means they may tear up the threads on their way out.
 
Mine did not mention shorter bolts either. Anybody know the specifics so I can order a set?

Freaking BHJ....
 
Yes they are bottomed out in the threads. Does not look like an easy .. or cheap repair.

- Dan
 
You might be able to drill the holes out larger and re-tap for larger (diameter) bolts - if you can't get the broken bolts out safely.
 
Can you drill the holes all the way through?

1. Drill a small pilot hole from the thread side
2. Flip the balancer over and drill a bigger hole through from that direction
3. Drill it big enough to remove the remaining bolt parts
4. Then drill it the same distance inon all 4 holes (basically to balance off the material removed)
5. Could use shorter or stock length bolts after that
6. MAYBE fill the backside with silicone to seal it and keep it clean on the bottom/backside of the threads

I would use a new pulley as that one is damaged. Could have stress cracks and be out of alignment. OR just a bigger washer (might need to grind a flat spot on the edge to get it to fit in place flat on the mating surface.
 
That happened to me and why I parked the car for the winter. It's going to a machine shop to let them sort it out.

Edit: And like someone else mentioned in the other thread, it sounded like I had a rod knock it was so loud. God only knows how that harmonic (before I could hear it) was effecting the timing/tune.
 
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Mine did not mention shorter bolts either. Anybody know the specifics so I can order a set?

Freaking BHJ....

I went to the local hardware store and picked up some Metric bolts with a Flange on the head just like the stock bolts - no washers.

Size is M8 x 25mm 1.25 pitch ... stock length is 30mm, so I figured 25mm was about the .25" shorter size.


- Dan
 
I know this is an old thread, but I've got this same problem. Broken pulley bolts, all 4 of em. The knocking sound was the beginning of stress..... I've got a BHJ with the March underdrive pulley. I'm using the stock bolts (not anymore). What is the correct size bolt that I need? Also, Do I need to pull the balancer to re-thread it or can I tap threads in it while it's still on the crank? I have the Craftsman tap & die set. Maybe I can just run my drill through it and then chase it with the tap set.
 
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I know this is an old thread, but I've got this same problem. Broken pulley bolts, all 4 of em. The knocking sound was the beginning of stress..... I've got a BHJ with the March underdrive pulley. I'm using the stock bolts (not anymore). What is the correct size bolt that I need? Also, Do I need to pull the balancer to re-thread it or can I tap threads in it while it's still on the crank? I have the Craftsman tap & die set. Maybe I can just run my drill through it and then chase it with the tap set.

I would take the balancer off just to make sure everything is drilled and tapped perfectly straight.
 
I know this is an old thread, but I've got this same problem. Broken pulley bolts, all 4 of em. The knocking sound was the beginning of stress..... I've got a BHJ with the March underdrive pulley. I'm using the stock bolts (not anymore). What is the correct size bolt that I need? Also, Do I need to pull the balancer to re-thread it or can I tap threads in it while it's still on the crank? I have the Craftsman tap & die set. Maybe I can just run my drill through it and then chase it with the tap set.

The size is listed 2 posts above yours.

I would try a reverse twist drill bit and see if you can spin out the bolt remains.

If they do come out, I would then chase the threads with a thread repair tap, preferably bottoming variety.

If not, you may be better off pulling it.
 
Ok, pulled the pulley & balancer. The balancer looks ok. The threads are stripped on one hole for about 4 threads down. The other 3 look good. I'll try to extract them tomorrow evening. I'll then drill the holes a little bit deeper on my bench, hope my Dewalt carbide drill bits get the job done. Should I try to make the holes bigger? It also looks like I'm now in the market for a March crankshaft pulley. I think mine is toast. If I put washers on it and bolted the new bolts down real tight, I think the pulley could still move and I would have to continue with this headache...
 

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Also, as I was removing my BHJ balancer, it came off with ease. It started tough, as usual, with the harmonic balancer puller. Toward the end of the crankshaft, though, it practically slid right off. I was able to slide it back on almost all the way with a little force, but just by hand. This isn't supposed to happen, is it? :(

This isn't the 1st issue I've had with a BHJ... http://www.sccoa.com/forums/showthread.php?130431-BHJ-Balancer
 
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As far as the pulley goes, I would feel better if the holes were tighter, but the clamping force of the bolts is really what holds it in place. I would try bolting it down, as long as you have good threads in the balancer to apply the proper torque. The torque rating is determined by the fastener size and grade. If the bolts are grade 10.9, they should tighten to 20-24 ft-lbs. If they are grade 8.8, they should tighten to 14-17 ft-lbs. Don't overdo it.

I am not sure how tight the fit of the BHJ should be.
 
The balancer's been off for almost 2 weeks now. I drilled a hole in the 1st broken bolt with a carbide bit using a hand drill on my work bench. It wasn't the easiest thing to do. However, my back wasn't hurting like it would've had I been bent over the radiator, hanging upside down, drilling out a broken balancer bolt. So I was happy about that.

The bad news, after I put in my Dewalt extracter bit, the broken bolt wouldn't move. It was just my luck, the bit broke off in the bolt. So I took the BHJ & pulley down to Mike's http://www.mikesautomotive.net/ down in south St. Louis. They did the machine work on my engine block & heads 7 years ago. My Dad was going to them since the '80's. Turns out, the broken bit had to be burned outta there. They didn't do that part, some hole in the wall joint on South Broadway did that. Then I had them drill me 4 new holes in the March aluminum pulley to match it up. Now I'm just waiting for them to give me that sweet zero balance I so desperately need. I'm hoping it'll be ready by this Saturday.
 
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