Broke another flexplate, what am I missing?

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Blackbeard44

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I would fire it up and watch closely for end play in the crankshaft, maybe a thrust bearing has become sloppy.

you sure the motor is definatley a 350, if its a 400 or 327 it will take a different style flexplate.
 
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79dentside

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Blackbeard44 said:
I would fire it up and watch closely for end play in the crankshaft, maybe a thrust bearing has become sloppy.

you sure the motor is definatley a 350, if its a 400 or 327 it will take a different style flexplate.
Click to expand...

Should be a 350, but I haven’t run the numbers to be honest. Motor has less than 25,000 miles on it, really doubting it is crankshaft end play, but who the heck knows. I ran it without the flex plate dust cover and didn’t notice any wobble. It’s also very noisy, so I got a quick look and then shut her down.
 
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snap a pic of the harmonic balancer on the front of the crankshaft, what side of the engine is the dip stick on.

i have seen flexplate crack pretty rarely, for a motor to go through 2 of them in short time like that I would dig a little deeper
 
Cuba

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I would think bushing on the front pump would be a likely culprit. Everything needs to be square to each other to avoid stress. If the bushing is worn... that slight angle is more pronounced by the time it reaches the other side of the Torque converter. It may not leak if the seal is still pliable.

Yes, I have seen crank shaft having excessive play or runout (front to rear) to cause this issue too... but the whining has me leaning away from this. You can always remove the belt from power steering (to eliminate this possibility) , especially is the setup still has the multiple v belt. Just be sure water pump & alternator are still going.

I definitely want to follow this... see what the cause ends up being. :hmm:
 
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79dentside

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Blackbeard44 said:
snap a pic of the harmonic balancer on the front of the crankshaft, what side of the engine is the dip stick on.

i have seen flexplate crack pretty rarely, for a motor to go through 2 of them in short time like that I would dig a little deeper
Click to expand...

Drivers side dipstick, 8” dia. dampener. Previous owner said it was a 350, I’m not sure why it wouldn’t be. I don’t have any pictures of the dampener, just of the motor.
You must be registered for see images attach
 
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Cuba said:
I would think bushing on the front pump would be a likely culprit. Everything needs to be square to each other to avoid stress. If the bushing is worn... that slight angle is more pronounced by the time it reaches the other side of the Torque converter. It may not leak if the seal is still pliable.

Yes, I have seen crank shaft having excessive play or runout (front to rear) to cause this issue too... but the whining has me leaning away from this. You can always remove the belt from power steering (to eliminate this possibility) , especially is the setup still has the multiple v belt. Just be sure water pump & alternator are still going.

I definitely want to follow this... see what the cause ends up being. :hmm:
Click to expand...
I’m hoping it’s a pump bushing too..
 
Cuba

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if you happen to hear the whining again. Try pulling trans dipstick... see if there's cavitation or bubbles/foaming. Then there's something up with the trans internally anyway. Either valve body issue or maybe filter.

Beautiful pic BTW. Not much rust from the looks of it.
 
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79dentside said:
I’m hoping it’s a pump bushing too..
Click to expand...

Well, it's not the easiest to replace if trans pump isn't removed. The shafts make it a PITA to remove or install. The seal, not too bad.

How many miles, approx? Edit* read initial post. :D
 
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Cuba said:
Well, it's not the easiest to replace if trans pump isn't removed. The shafts make it a PITA to remove or install. The seal, not too bad.

How many miles, approx?
Click to expand...

The trans I have no idea. Motor and rear gears have 24k and change. Trans has some leaks so it doesn’t seem to be freshened up anytime recently, but it has a pretty fierce shift kit in it so I know someone has been in it. May be time for a pump. Looks like this is getting more and more fun... lol.
 
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lol.. they aren't too bad to do. Im thinking you might have the 4l60.... or 700r4. If it winds up needing to be done, I'd add a TransGo kit... to improve lubrication to certain components and installs fail-safes. This will help prolong overall life, even with a shift kit & driving it like you stole it. Lol

Edit* Goodness! I need to learn to read. Once again I reread 1st post. TH 350... ok. TransGo makes a kit for that too. Prolong clutch pack life and such. The SK 350.

My apologies
 
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79dentside

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Cuba said:
lol.. they aren't too bad to do. Im thinking you might have the 4l60.... or 700r4. If it winds up needing to be done, I'd add a TransGo kit... to improve lubrication to certain components and installs fail-safes. This will help prolong overall life, even with a shift kit & driving it like you stole it. Lol

Edit* Goodness! I need to learn to read. Once again I reread 1st post. TH 350... ok. TransGo makes a kit for that too. Prolong clutch pack life and such. The SK 350.

My apologies
Click to expand...

No worries haha, you are helping me no need to apologize. I considered having it rebuilt... just analyzing opportunity cost, it’s not a high dollar truck by any means. Would really hate to spend a bunch of money, yet I really don’t want to do any of this again so it may be worth it.

As far as the trans bushing being bad, I have never done one and looked into it.. looks like that is going to be no fun... not really sure where I want to draw the line here. None of this is looking too good.

Hopefully this all is just because the flexplate bolts were wayyyy over torqued (Which I can promise that they were) :)
 
Cuba

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You should be able to at least see if the bushing is worn, depending on how far out the trans is coming out to gain access to flexplate replacement. It should give you an idea of what may be going on, a direction.... or maybe something ruled out... never know.

I hear you on wanting to draw the line. Toys are nothing but money eaters... but still cheaper than most Jeeps? Lol :emotions33::D
 
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Cuba said:
You should be able to at least see if the bushing is worn, depending on how far out the trans is coming out to gain access to flexplate replacement. It should give you an idea of what may be going on, a direction.... or maybe something ruled out... never know.

I hear you on wanting to draw the line. Toys are nothing but money eaters... but still cheaper than most Jeeps? Lol :emotions33::D
Click to expand...

Ha! Yeah I will not enter the Jeep game, no way! I like these old trucks. I use it all the time, great pieces of equipment to say the least.

I am not sure what my game plan is. I need to find a place and a time to do said swap. It’s quite cold out.

Right now I will probably just begin accumulating parts. I know I will be doing an HD flexplate, 2,200 ish stall converter, trans filter and a transmission pump. When I have it apart that’s when I will check that trans out a little closer. It needs a pan gasket and a dipstick tube gasket anyways as they are both leaking. I might as well get it completely out so I can do that too. Then I may decide to have more done if it’s reasonable on cost.

Question, were there any washers or spacers that are to be used on the flexplate/torque converter? I didn’t use any, but it was a thought that occurred to me.
 
Cuba

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Regarding the spacers or washers, not on this that I'm aware of... BUT due to the fact you have a TH350, a trans I don't personally see much, there may be a difference. I don't want to misinform. Can't hurt to do more research on that part. Maybe ask your trans guy friend. I rebuild many, but I know I'm no expert in that field.
 
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