Harmonic Balance play

[6SENSE]

Broke down my engine to swap cams and noticed the harmonic balance doesnt fit snug on the crank/keyway. You can move it side to side pretty good. I checked another block that I had sitting aside which didnt have this problem, fit snug. After comparing, it seems that my keyway and the notch on my harmonic balance are both worn.
Im thinking that once everything is together and bolted tight it shouldnt move around (maybe). So Question is how big of a deal is this? Should I be worried about this now, and change keyway and harmonic balance?

P.S. keyway is not worn where lower timing chain gear is, just in front of it.

 

[6SENSE]

Also,
What will this affect? The only thing I can think of would be the crank sensor, right? If so, as long as the car starts up fine, there is no issue?

 

[bruce]

Originally posted by 6SENSE
Broke down my engine to swap cams and noticed the harmonic balance doesnt fit snug on the crank/keyway. You can move it side to side pretty good. I checked another block that I had sitting aside which didnt have this problem, fit snug. After comparing, it seems that my keyway and the notch on my harmonic balance are both worn.
Im thinking that once everything is together and bolted tight it shouldnt move around (maybe). So Question is how big of a deal is this? Should I be worried about this now, and change keyway and harmonic balance?

P.S. keyway is not worn where lower timing chain gear is, just in front of it.

You might try a new balancer, and keyway, but don't be surprised if they fail and take out the crank.

If the crank has a mottled look where the balancer rides, you probably have enough slop in there, that the problem will reoccur.

When I bought my GN the guy said he'd just put a cam in it, well the only problem was that he didn't torque the crank bolt down correctly and it cam loose causing exactly what you discribed.

A real no joy situation.

 

[6SENSE]

Well that wasnt exactly what I wanted to hear, doh!

I believe that is what happened, except Im the dummy that didnt tighten the bolt down properly the last time I was in there. I remember finding the bolt loose a little while ago and I just went ahead and tightened it up. I guess it was loose enough to to wear the keyway and balancer.
The crank doesnt look out of the norm at all where the balancer rides, just the keyway itself and the balancer notch. I guess I will just change those and hope for the best.
Im guessing that this is something that I'd better take care of now or it will only get worse, huh?
Anything special about these keyways? or are they the same that you can find on any .231/3.8?

Thanks.

 

[Lee Thompson]

bolt

Depending on what book you read, these bolts require 225-250 ft. lbs. The reason they torque this tight is to prevent what has happened to yours. Best of luck

 

[gnsrule]

Theres some stuff out there calld "Gapper". Made by Permatex I belive. Its used to fill in shafts, bearing bores etc... up to 0.100. I used it a few years ago, it works.
The keyway is used to line up the balancer only. So, with the balancer installd, if you cant wobble it back and forth too bad, the gapper might be the cure. Also, dress up the end of the balancer snoot and the face of the crank gear with a file so they'll grip when there torqued w/ an *cough* impact *cough*

 

[6SENSE]

Thanks guys!

I swiped the keyway and balancer from the other motor I had around and now fits snug, hopefully that will be the end of this problem.
Kind of weird though. After further inspection of the keyway and balancer that I took off my motor they dont really look worn. The keyway looks to be cut differently. It is wider on the end where the lower chain gear rides and cut narrower where the balancer rides. It is definately machined this way, there is a ridge, etc. where the change in width occurs. Also, after further inspection, the balancer just looks like it has a wider notch in it than the other balancer (not worn, looks like it is made this way).
Have any of you found these differences before? I dont think this was the balancer that was on my engine when I got it. I put this balancer on because the ring on it was in better shape, the other one was bent a little and rubbed the crank sensor (I think). Now Im thinking that the original balancer must have matched the funny keyway. Something else to be aware of when swapping parts, huh? Is this normal to find?

P.S. thats a pretty cool picture, the machine shop even found a way to run the crank on top and the cam on the bottom of the engine! Now its not a V6 its a /\6 .