You can check the large bolt in the middle to see if it has worked loose, but more likely, if you look closely, you'll probably see that the center hub is not wobbling. Only the outer ring will wobble if the rubber material sandwiched in between breaks loose. This has become a common problem on any car, and the auto parts stores have entire catalogs full of replacements. They are called harmonic balancers or vibration dampers.
January, 10, 2012 AT 4:35 AM
Here's a photo from rockauto. Com of the part for a 3.4L engine. Two different parts are listed for the 3.8L. Notice the thin sheet metal ring with all the rectangular notches. If the center bolt was loose and the hub was wobbling around, that ring would have chewed up the crankshaft position sensor and the engine would have stopped running. It doesn't sound like that's what happened. Sounds like the outer ring is about to fly off.
January, 10, 2012 AT 5:55 AM
Thanks for the help caradiodoc. Is this an expensive repair or can I do it myself?
January, 10, 2012 AT 6:44 AM
That is listed between 62 and 136 bucks from the discount supplier. Expect it to cost more locally but you won't have to pay shipping. You also might consider getting a used one from a pick-your-own-parts salvage yard. There's a real nice chain of yards between Ohio and southern Georgia called "Pull-A-Part". The part will typically cost about ten bucks plus the dollar admission, and you have to bring your own tools. Once you see what is involved in pulling that one off, you'll know if you want to tackle putting it on your engine.
The center bolt must be removed. That is fairly straight-forward, but then the damper must be pulled off the crankshaft. Some slide off real easily with little more than a small pry bar. Some require a puller. You'll see three holes in the damper in the photo. That is where the bolts go for a three-jaw puller. It is important to not use a puller that has hooks that go on the outside. That will pull the ring off and destroy it.
Be sure to tighten the puller's bolts evenly so it slides off straight. If it gets off-center that thin ring can damage the crankshaft position sensor. Be sure the damper stays straight when you use the center bolt to install it.