My harmonic balancer came off

[Stan G.]

Hello, I know this has been discussed in the past but yesterday I fired up the 58 to take it out , when I heard a loud bang from the engine compartment , shut it off and find that the balancer and pully have come off and are laying on the garage floor.Now searching the archives I see that the fix is to drill and tap the crankshaft and install a bolt to hold it on.Can't do that in the car , so i'm going to install a new balancer.Is there a good source for them.The car is not being judged so the correct number doesn't matter , I just want it to stay on.
Also I have noticed some oil on the floor under this area , could it be because the balancer was apparently not in direct contact with the crank? Is there a seal that can be installed to stop this leak without pulling the timing chain cover ?

Thanks for any info, Stan.

[Mike M.]

Re: My harmonic balancer came off

i'd install a sleeve designed to overcome any grooving of the harmonic balance and i'd remove the timing chain cover and install a new seal in the cover. you may be able to remove the seal with the timing cover on the engine but it'd be a real bear to install the new seal. i'd drill and tap the crank(although its a difficult proceedure with the engine in the car). not sure you want to hear this. good luck,mike

[Joe L.]

Re: My harmonic balancer came off

Hello, I know this has been discussed in the past but yesterday I fired up the 58 to take it out , when I heard a loud bang from the engine compartment , shut it off and find that the balancer and pully have come off and are laying on the garage floor.Now searching the archives I see that the fix is to drill and tap the crankshaft and install a bolt to hold it on.Can't do that in the car , so i'm going to install a new balancer.Is there a good source for them.The car is not being judged so the correct number doesn't matter , I just want it to stay on.
Also I have noticed some oil on the floor under this area , could it be because the balancer was apparently not in direct contact with the crank? Is there a seal that can be installed to stop this leak without pulling the timing chain cover ?

Thanks for any info, Stan.

Stan------


You can replace the balancer with a GM #3896904. It's now GM-discontinued without supercession but there should still be some around. If not, no problem. You can get an identical balancer in the aftermarket from NAPA and other sources. The GM #3896904 is configured differently from your original but it will fit and perform perfectly. A new balancer should cure your balancer retention problems AND any grooving of the seal surface in one fell swoop.

The only seal involved in the whole system is the front timing cover seal. These can be replaced with the cover still installed on the engine but I don't recommend it. There's too much chance that you'll distort the cover in the removal process and then you'll have to remove (and replace) the cover anyway.

[Roy B.]

Re: My harmonic balancer came off

Replacing the timing seal is not that big a deal ,done it many times in the past just be carful tapping it on and using a new balance you'll probably never have that happen again.

[Tom S.]

Re: My harmonic balancer came off

That happened to my wifes car years ago. It was a Pontiac Grand Prix. The wierd thing was I had it in the Pontiac garage and told them I had a strange sound under the hood somewhere. They said they could not find anything wrong. So the next week my wife is going to work and right in front of the Pontiac dealership the balancer came off. At least she didn't have a long walk.

[Stan G.]

Re: My harmonic balancer came off

Hey thanks for the response.So what I'm hearing is that a new balancer will solve the problem of coming off again in the future? The best part of this whole problem was where it hapened.It could have happened out on the road somewhere and not in the garage. You have to find a bright spot in every setback. I'll check my autoparts today.Did not want to try drilling the crankshaft and tapping while on the car.

Thanks,Stan.

[Michael F.]

Re: My harmonic balancer came off

It's made it over 50 years without being tapped. No reason to do it now. A new unit will solve your issues. The seal may not even need replacing. It may have dropped the oil when it spun off. If it was backing off slowly? The oil leak probably start then. Lucky it didn't fly off doing 70 on the highway.

[Randy G.]

Re: My harmonic balancer came off

Back in the 1970's I had one come off my 1960 (I was a 19 year old kid at the time). I went to install a replacement balancer and had a little surprise. The old balancer evidentally had been loose for quite a while. Before the balancer worked itself off the crank it damaged the front of the crank shaft to the point where it the crank snout was undersize.

Since the balancer is a press fit I had no other option but to pull the engine and replace the crank. Today there are companies that can weld, remachine and heat treat the front of the crank.

I think just because they didn't put a bolt in the crank back then it is no reason to ignore the fact they they need one now. And in case you are able to press a new balancer on without replacing or repairing the crank I would strongly suggest changing the front seal. They are cheap and easy to do. You are changing the sealing surface when you put a new balancer on.

RG

[Joe L.]

Re: My harmonic balancer came off

Back in the 1970's I had one come off my 1960 (I was a 19 year old kid at the time). I went to install a replacement balancer and had a little surprise. The old balancer evidentally had been loose for quite a while. Before the balancer worked itself off the crank it damaged the front of the crank shaft to the point where it the crank snout was undersize.

Since the balancer is a press fit I had no other option but to pull the engine and replace the crank. Today there are companies that can weld, remachine and heat treat the front of the crank.

I think just because they didn't put a bolt in the crank back then it is no reason to ignore the fact they they need one now. And in case you are able to press a new balancer on without replacing or repairing the crank I would strongly suggest changing the front seal. They are cheap and easy to do. You are changing the sealing surface when you put a new balancer on.

RG

Randy-----


Yes, there is the possibility that the crank snout is damaged and, if so, something will need to be done about it. So, the crank snout should be inspected for damage and precisely measured to be sure the OD is still what it needs to be.

If a crank snout is damaged, folks should not consider the "solution" to be just tapping the snout for a balancer bolt. All that does is ensure the balancer will not come off. The proper FUNCTIONING of the balancer depends upon the proper interference fit between the balancer and the crankshaft snout.

[Stan G.]

Re: My harmonic balancer came off

Hey thanks for all of the help. Have not picked up another balancer yet,but I will definitly look at the front of the crank for damage.I'm hoping that its a case of just a wore out balancer.It was a rebuilt 283 I picked up down in Cypress Gardens when the Fla. Chapter was still holding their Jan show down there.The motor only has a few hundred miles on it but it was a used balancer I got out of Calif.


Thans , Stan

[Stephen B.]

Re: My harmonic balancer came off

Stan
I recently rebuilt the correct numbers matching motor in my 59. I specified that the crank be drilled and tapped. One of the resones I absolutly would not want an untapped crank is the motor that came out of this car had a hamonic balancer that would float back and forth on the nose of the crank. The only thing that kept it on was the belt.I also suggest using some lock tight on the bolt if you go this route. There's a reason why GM started tapping their cranks. Can you imagine the damage thats been done over the years, for the lack of one bolt?
Stephen Barrett (21558)