Buick Century chronic harmonic balancer problem

[HoratioTheJeep]

Need some help/input: What could cause a harmonic balancer to repeatedly go bad? When I say, "go bad," I mean it starts to wobble & make a lot of clatter. Also seems to destroy crankshaft position sensors.

The first time this happened, I let it get to the point where the crank sensor was toasted & the car would stall or not start. The mechanic replaced the sensor without replacing the balancer, but it kept wobbling and making a clattering/hammering noise, so I took it back & had them replace the balancer as well.

Now, 2 1/2 to 3 years later, the balancer is wobbling again, and the crank sensor caused the car to stall twice, and once caused a no-start condition. I'm sure if I just replace the balancer and sensor, the same problem will come back to haunt me in another couple of years -- so what should I look for? Is there something internal to the engine, that is causing the balancer to wobble until it ultimately destroys the balancer and the crank sensor? Is there some bushing somewhere, that could be worn out & needs to be replaced before yet another balancer is installed?

I've done basic repairs on my Jeep before, and I have a few tools, but the Buick is kind of a different animal, being FWD and all, and with less room to work in the engine bay. I suspect I will end up taking this to a shop, but first I'd like some input from somebody who's messed with harmonic balancers before (on any car), so I know how to deal with the repair shop when they feed me a line.

[p.s. - this question also posted on JeepForum, so if you are a member there, too, please respond on only one forum - I will see your reply, I promise!]

TIA,
--Matt

 

[YELLAHEEP]

Is this the 3.8 V6? There seems to be a bit of a problem with these engines but it depends on the year. What car are you working on specifically?

Generally, balancers go bad when the rubber dries out, or gets saturated with oil. When you say it "wobbles", is it up and down like off center? Or does one side of the ring get closer to the timing cover and the other side farther as it spins around?

Things I've read about this issue indicate that the front main bearings tend to go bad, but when that happens, you don't have smooth operation of the engine, usually a bad vibration and some knocking sounds as it gets worse. I can't imagine you'd have a bad main bearing - wouldn't have lasted 2.5 - 3 years.

You might also look on line to see what re-calls or Technical Service Bulletins have been issued for your Buick.

 

[HoratioTheJeep]

Is this the 3.8 V6?

Oops, no, I should've specified -- it's the 3.3 V6. 1992 Buick Century "Custom" (garden variety). Sorry I forgot to mention that!

Generally, balancers go bad when the rubber dries out, or gets saturated with oil. When you say it "wobbles", is it up and down like off center? Or does one side of the ring get closer to the timing cover and the other side farther as it spins around?

One side gets closer to the timing cover & the other side farther. Definitely. Doesn't appear off-center at all.

Interesting. This ugly beast does have an external leak from the intake manifold gasket (i.e. it is not leaking into the top of the engine, but on the outside of the block), which I suppose might be dripping down onto the rubber part of the balancer... but then I don't see that causing the rubber to dry out. Maybe if it were coolant.... Anyway, I'll have to take a close look at any signs of a leak in that area, especially a coolant leak, something might be damaging the balancer that way.

Things I've read about this issue indicate that the front main bearings tend to go bad, but when that happens, you don't have smooth operation of the engine, usually a bad vibration and some knocking sounds as it gets worse. I can't imagine you'd have a bad main bearing - wouldn't have lasted 2.5 - 3 years.

Engine seems to run smoothly and quietly, other than the tremendous clatter from the balancer. Right now I do get what feels like driveline vibes at 65-70mph (manifested in a suddenly squeaky and rattling dashboard ~65mph), which seemed to happen before, as well, when the previous balancer was going bad. I was never clear on whether that was an effect of the balancer going bad, or possibly a CV joint -- but I've been noticing the vibes off and on for years, now, too, so I've stopped trying to diagnose that problem as it seems not to be fatal.

You might also look on line to see what re-calls or Technical Service Bulletins have been issued for your Buick.

Doh! I feel like a nOOb. You are right, I need to look into that.

Thank you, Yellaheep, your post has been very instructive! If you think of anything else, let me know. I'll try to report back when I get a closer look at the balancer, and/or if I find a TSB on some such problem.