harmonic balancer 92 buick lesabre

My husband is trying to replace the harmonic balancer on our '91 buick lesabre. After he finally got it off, he realized the oil seal was bad, so we was going to replace it, also. He has been unable to remove the key way and broke something that the key way slips through. What is this and where is the crank trigger sensor?

If your husband is naming these parts for you, then he already knows what they are. By the way, what is a key way? Are you referring to the small piece of metal, shaped like a half flat football, that goes in a groove in the crankshaft? If so, what exactly did he break, the groove? the small piece of metal that goes into the groove? Either way it is bad. You might be looking at having to pull the engine to both repace the crankshaft and repair the main oil seal. Doing it in the car is very frustrating and difficult. If you must do this, consider junking the car and buying a different car. Fixing yours is probably not cost effective. But if you must fix it, and if you do remove the engine, take the time to get new bearings, piston rings, pushrods, a timing chain, and maybe get the heads reconditioned (or at least thoroughly cleaned). Before doing anything, however, do a compression test and see if the motor has any excuse for living. If compression is poor, the engine may be too worn to fool with.

Oh, and the crank sensor is directly behind the harmonic balancer. It is the small piece of plastic and metal that has two slots that the balancer turns through. It has a wire harness connected to it. The wire harness up a little higher goes to the camshaft sensor.

I'm not sure I understand what broke either... can you send a picture?

Here's some unhelpful info: I used to do some work on those "balancers". I'm pretty sure that all the 3.8L back then had what we called an Isolator. Besides the pulley, it has a huge piece of rubber in it and a small bearing. There are 2 stainless steel rings with slots on the engine side of the Isolator, that are held in by 4 tamper proof screws. (don't remove the screws; that will affect timing). Some of the early versions may have only had one ring(?) These slotted rings pass thru the sensor that is mounted on the front engine cover.

If you need to replace the Isolator, I understand that they are very expensive at the dealer. As for used parts; I also recall that even though they look the same from year to year, the counterweight size changed every year or two. So make sure you get the right one, or you'll end up with a bad vibration.

Good Luck.