2000 Tahoe flywheel bolts sheared off. How'd that happen?

[Diesel6point6]

Hi guys, wondering if you could shed some light on how this might have happened because I have no idea, and I'm really curious. I bought a tahoe with a suspected bad transmission. I just pulled the engine and trans together and went to take out the flywheel bolts and was shocked to see there weren't any. Got the tranny and engine separated and could clearly see the bolts had all been sheared off, a lot if carnage was done to the flywheel itself, the rear cover, and the oil pan. What could have caused that? Engine was running really smooth before pulling.

 

[Diesel6point6]

Just realized I put this in the wrong section. D'oh! Mods, can you please move or delete and ill repost in the correct one? My bad.

 

[Scottydoggs]

my first thoughts are someone drove it like they stole it. aka beat the living crap out of it one day. and came home on a tow truck, then sold it as is, "has a bad tranny" now you get to fix it.....

 

[nonickatall]

I guess something blocked the transmission while engine was running at high revolution. Probably something in the transmission or in the transfer case stuck.

Can your turn the input shaft of the transmission?

I don't think that it's possible to do that damage, by shifting into P or R while driving.

 

[strutaeng]

Post some photos so we can have a better idea and do some wise speculation...

 

[Mudsport96]

Could be a couple things.
1. Hard part internal transmission failure Locked the pump up and stopped the converter.
2. Reverse drop/neutral drop shock loaded the flexplate.
3. Bolts started to work loose then the flexplate beat them to death.
4. Gremlins.

 

[nonickatall]

Could be a couple things.
1. Hard part internal transmission failure Locked the pump up and stopped the converter.
2. Reverse drop/neutral drop shock loaded the flexplate.
3. Bolts started to work loose then the flexplate beat them to death.
4. Gremlins.

I guess gremlins is the most likely issue...

 

[Diesel6point6]

I guess something blocked the transmission while engine was running at high revolution. Probably something in the transmission or in the transfer case stuck.

Can your turn the input shaft of the transmission?

I don't think that it's possible to do that damage, by shifting into P or R while driving.

Yes, input shaft spins freely. A bit squeaky, but freely nonetheless.

Post some photos so we can have a better idea and do some wise speculation...

I've attached some photos of the carnage. First of the bolts sheared off in the torque converter (I should have been more clear in my original post that it was these, I thought later it might cause some confusion and some might think it was the bolts attaching the flexplate to the block, those were still intact), 2nd is the flexplate, 3rd is one of the bolts I found inside the bellhousing, 4th is of the rear of the engine (sort of hard with it on the engine stand)

 

[strutaeng]

I guess one possibility is the flexplate bolts (somehow) worked themselves loose, and they kept driving until the flexplate bolts hit something and flexplate fell off? I don't even know if that's possible?

What are you going to do to the truck? I would be checking engine front-to-back endplay just to make sure you don't have a destroyed thrust bearing.

IDK what to even say about the transmission, as far as if damage was a possibility. Probably front end play as well. @NickTransmissions may offer some advice.

What did the previous owner tell you about the truck? Is that even known?

 

[Diesel6point6]

I guess one possibility is the flexplate bolts (somehow) worked themselves loose, and they kept driving until the flexplate bolts hit something and flexplate fell off? I don't even know if that's possible?

What are you going to do to the truck? I would be checking engine front-to-back endplay just to make sure you don't have a destroyed thrust bearing.

IDK what to even say about the transmission, as far as if damage was a possibility. Probably front end play as well. @NickTransmissions may offer some advice.

What did the previous owner tell you about the truck? Is that even known?

Yeah I read some threads that mentioned sometimes one bolt backs loose from the torque converter, which then in turn gets everything out of whack and it eventually causes carnage if it keeps getting driven. My best guess is this is what happened to this one.

I'm going to swap it into my S10. This is the 3rd one I bought with that purpose, the first 2 I didn't have the heart to pull the engines out and still drive to this day haha! I guess you can say I have a love for these SUVs. But would the engine sound as good as it did before pulling if there was a destroyed thrust bearing? My knowledge in this department is very very limited.

The previous owner said the transmission was bad. Said he was driving it one day, heard a clunk, then no movement. Which makes sense, if the torque converter fully separated from the flexplate that would make the vehicle immovable. I have my suspicion if the tranny is in fact still good though? Again, my knowledge is very limited so I could be way off base here, but the torque converter bolts separating from the flexplate would exhibit behaviors of a bad transmission (just revs), but that could be because there was just nothing attaching the engine to the torque converter at that point, but the internals of the transmission are still good? Idk lol.