its standard thread, i use a pipe on the ground and bump the key. works every time. assuming the CPS isnt the issue, take the entire ICM off and check the back side of it and the mount on the engine. ill bet you $20.00 if you didnt already do it, there is tons and tons of corrosion. i sanded it all off and the car ran perfect again. ( random missfire and stalls on mine)

A friend just sent me a video of using the starter motor, with breaker bar braced on frame wish I would of known that before I wore myself out. will try it tomorrow an let you know how it worked. thanks for the pointer. I'll try the frame or a pipe on the floor see what looks safest.

Do NOT heat the balancer, it will ruin it, it is rubber mounted and engine seals are behind it, do you need it off to change sensor? (some don't) sensor is usually bolted to front of motor just behind balancer but it goes on and off without moving balancer. if balancer needs to come off you will need to use a puller designed for it. they are usually cheap if you need to buy one. not quite sure which motor you are working on I'm assuming a V6.

didn't see 2nd page on my comp. I use a strap wrench to hold the balancer, jamming ring gear does work just be sure not to damage the teeth or bend the flex plate. as for strength I use a long breaker bar for leverage.

You will most likely need a cheater bar over the handle to break the bolt free. Use a jack stand to hold the extension for your breaker bar so you can really apply force. It'* going to take a LOT. You may need to add a pipe extension to your breaker bar.

I have the 3800 SC engine it would be great if I didn't have to pull the balancer. the service manual says I need it removed? but I know that they aren't always correct? Any knowledge about if it needs to come off for this engine in the PA will be appreciated.

There is no way to change your crank sensor without pulling the harmonic balancer.

I'm with the others. You need to pull the balancer using a special tool. Which requires different bolts that thread into the balancer itself.

Dan has a good writeup and needed info...

https://www.gmforum.com/mechanical-134/harmonic-balancer-replacement-286278/

Thanks mike but I can't access that write up for some reason, I was pretty sure I would need to pull it. I guy can hope, lol have some welding to do for a buddy then will pull the balancer. positive attitude. please don't tell me I need to pull the motor mount on the front of the engine. well tell me if you have too .lol thanks everyone, it all helps.me and the others looking for these same answers.

I had a hard time with the bolt on the harmonic balancer and then after the bolt I had a hard time with the harmonic balancer itself. I had to buy a heavier air impact wrench and impact socket take the cover off of the flywheel and jam the flywheel with and oversize screwdriver against the frame to get the bolt loose on the harmonic balancer. Then I had to get the correct screws length, size and pitch for a three bolt puller to finally remove the harmonic balance. I believe that there are rubber parts in the harmonic balancer so it is not advised to take a torch to it. The worst of it for me was the bolt I really had to hammer on it. The manual says to replace the bolt that hold the harmonic balancer every time but I know people who have reused that bolt many times.
I may be having the same trouble though mine is not diagnosed yet as my problem is intermittent. I am also not showing any codes that might explain the intermittent engine dying problem. While I do not know if this is my problem the crank sensor is known to sometimes throw no code.