flywheel turns but engine won't crank

[bradwill]

Hello everyone, I have a question about a problem with my 2005 Silverado 2500 hd 6.0l. For some background, I managed to get the truck back from a mechanic I had working on it but I had to have it towed back to the house. He was doing stuff that I didn't authorize him to do and I'm not sure what all was done. He said it wouldn't crank because there is a problem with the flywheel - which is something he wasn't supposed to be messing with anyway. The truck was running when I brought it to him to change out the wiring harness on the engine.

Anyway, I replaced a couple of things myself, the last one being the starter because it was bad. Now the starter works; it engages the flywheel and the flywheel turns but nothing is happening with the engine. It's not trying to crank at all. He may have replaced the flywheel because it looks good to me - all the teeth are good, nothing cracked or broken that I can see. But it's way to easy to turn. I can do it by hand with no problem.

I'm not a mechanic but I know that's not right. It's not engaging something to turn the crankshaft. The engine is not frozen; I can turn it from the front center pulley and everything moves fine. So what could be the problem?

I need to know what I should see when I remove the flywheel and torque converter. I've been looking but I haven't found the diagrams or videos I need to see for that. Can anyone point me in the right direction for those?

[CamGTP]

The flex plate would have to be completely broken for it to not turn the crankshaft along with it. That means the flexplate broke where it's bolted to the crankshaft itself. There is no way to get at those bolts with the transmission in place, so it's super unlikely that the mechanic removed them. The only thing keeping the flexplate in line would be the torque converter bolts holding it in place.

 

 

 

[richard wysong]

Broken crankshaft is probably what it is, Pretty rare but I have seen 3 in my lifetime but never on a Chevy, could be as Cam says as well, much more likely

Edited March 23, 2023 by richard wysong

[newdude]

I suppose a crankshaft in two pieces is a possibility, but I'd pull the transmission and inspect the flywheel for being cracked where it bolts to the crankshaft.  They are notorious for it.  

[richard wysong]

I agree. The reason I thought crankshaft is that usually a cracked flywheel will make a lot of noise before it actually breaks, If you remove the inspection cover you will see the flywheel move back and forth with the torque converter if the flywheel is broken and if you remove the tc bolts that will confirm it before pulling the trans. I have had success  un bolting the bellhousing,trans mount and letting the engine and trans "hinge" enough to get in with a close tolerance Snap-On ratchet and un bolt and remove the flywheel. It saves a few hours of R&Ring the trans. There is no reason to remove the torque converter unless you are going to change it

Edited March 23, 2023 by richard wysong

[dna9656]

What a mess! I think you should contact a lawyer... You'll need written proof of what that guy with a lot of wrenches (I won't glorify him with the title of "Mechanic") was authorized to do. I'd threaten to sue for the cost of repairs and for the loss of use of your vehicle (rental fee you would have paid for a like vehicle or damages.....if he doesn't come up with some amount of money I'd really consider taking him to court. Especially if this is his living and he has a business lic. to protect.