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Awww..you ain't got shit!
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Discussion Starter · #1 ·
So, I am noticing some rattling under my truck. When started cold it sounds like say if you had a muffler with broken baffles in it rattling around. The noise is definitely not the engine, but centered around the torque converter when you crawl underneath. As the truck warms, the noise remains, but quietens up a bit. I'm thinking the flexplate has cracks between the bolt holes and as it warms up, it expands enough to make it quieten down. I know these are common to crack. Anyone else experienced a cracked flexplate that exhibited this kind of noise? It's not like a knock at all. It's a rattle. Like a gas tank would do with a stereo bumping...but constant. Truck runs fine. As said, it's definitely not the engine itself.

Your comments please. Hope all you guys are doing well!
 

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Awww..you ain't got shit!
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Discussion Starter · #4 ·
JK,
pull the inspection cover and look up there with a light.
I'm pretty sure you can see the front of the flex where it bolts to the crank.
That’s easy since I threw it away years ago. Seemed dumb cause the y pipe was in the way. 😂
 

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Might or might not be able to see the cracks around the bolt holes. Just because you don't see them doesn't mean they're not there, but it might be a way to find out immediately if you see cracks.
PITA to move the trans back, unbolt the converter, then unbolt the flexplate just to find out but that's the only sure way to know.

I used to hang out at a race shop and they replaced SFI flexplates yearly on rebuilds. I have a handful now and just take one of these to the shop and have them weld the balance weight in place, if needed. GM originals are junk compared to good ones.
 

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Awww..you ain't got shit!
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Discussion Starter · #6 ·
Might or might not be able to see the cracks around the bolt holes. Just because you don't see them doesn't mean they're not there, but it might be a way to find out immediately if you see cracks.
PITA to move the trans back, unbolt the converter, then unbolt the flexplate just to find out but that's the only sure way to know.

I used to hang out at a race shop and they replaced SFI flexplates yearly on rebuilds. I have a handful now and just take one of these to the shop and have them weld the balance weight in place, if needed. GM originals are junk compared to good ones.
What is a “good one”? I’m all about this not happening again. That’s for the info.
 

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Awww..you ain't got shit!
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Discussion Starter · #7 ·
Oddly enough I don’t see any cracks and the noise has almost ceased now. Hmm.....
 

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Awww..you ain't got shit!
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Discussion Starter · #9 ·
The "good ones" I have are TCI, all started life with an SFI sticker. They're definitely thicker and heavier.
thanks. If the noise ever returns....so far it hasn’t. So weird. My truck has headers on it. I drove it to the scrapyard with a load of crap in the trailer. I noticed it being noisier exhaust wise than normal right after I pulled out into the road. There was a brass plug that was where that air system garbage would be. It was missing. I fixed that and I also fixed the burned 02 sensor. No more noise. Now what the absolute blue blazes any of that would have to do with that is beyond me. No noise really to speak of. The noise was rightat the torque converter. I’m sure not related but that shit is weird.
 

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Awww..you ain't got shit!
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Discussion Starter · #12 ·
Had the problem several times already, broken flexplate/flywheel, the other time my catalytic converter broke apart inside its housing causing rattling sounds.
At first I thought it was the Magnaflow catalytic converter, but the noise was obviously at the torque converter. Who knows.
 

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I have some of the early snowflake wheels on my Tahoe. Had a rattle on the passenger side that sounded just like a bad cat. Turned out to be a wheel center that had lost it's ring and was rattling.

Good luck!!! As much as I hate to admit it, my experience has been that problems that disappear by themselves generally come back by themselves. Hope this isn't the case here.
 

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1992 s10 blazer 4.3 tbi
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I have a similar noise in mine. It does it idling most of the time and most often while just cruising. I can step on it and itll go away. The clutch pedal also has an affect on the sound while just sitting there. It wont make it go away but it does change the tone. Been driving it for a few years and still hanging in there lol.

I did however order a new clutch kit. I bought a 12” clutch, flex plate, and throw out bearing by Luk. I hope that itll fit. Rockauto said it would. Lol
 

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time to get cereal
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I did however order a new clutch kit. I bought a 12” clutch, flex plate, and throw out bearing by Luk. I hope that itll fit. Rockauto said it would. Lol
I hope you actually ordered a flywheel... flexplates are for automatics. Though usually you can just have your existing flywheel resurfaced.
 

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Awww..you ain't got shit!
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Discussion Starter · #17 ·
Noise is back. Since it cooled off it came back. Definitely has something to do with cooler weather. Same thing. Warms up? Gone. Takes a few minutes but it disappears. Feeling pretty sure that the flexplate is cracked. Ugh. Guess I'll get someone to replace it. My days of lifting transmissions lying on my back on the garage floor are over. Aging just rules.
 

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I’ve had my truck fit around 3-4 years and I’ve replaced mine twice. Now the new one is making noise so it’s almost time for number 3. I’m thinking it’s the torque converter that’s the problem but who knows. I feel like it could also be the little ring spacer that goes between the bolts and flex plate. Although I know exactly how to the the job, it makes me cringe when thinking about. Just getting the pipes dropped sucks.

Mine sounds kinda like a tick right now. In the past it turned into a knocking when it was bad. another thing I noticed is that the bolts are all loose when I go to change it. I use lock tight every time too.

Keep us posted on how it goes. I feel like this is a common problem.

Yowakawaka
 

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Awww..you ain't got shit!
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Discussion Starter · #19 ·
Yep. The stock ones are apparently very weak. What is odd is that this never happened on my truck when it had the 2.8 in it. Same transmission and torque convertor too. Since 2006 when it was rebuilt and still had the 2.8. Now, this plate is the one that came with the motor. Supposedly there are stronger alternatives. Think I'll look into that. For now it can rattle.
 

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Awww..you ain't got shit!
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Discussion Starter · #20 ·
@Salty Crusty

Hey, do you know how many teeth are on the flexplate? I see 142, 153 and 168. Can't find a reliable source to tell me which one is the correct one.
 
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