"rocks in a blender" sound in my wife's slant Valiant

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gregpurcell

Greg Purcell
Joined
Aug 21, 2008
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Near Savannah, GA
I finally found the problem! Actually I suspected all along that it would be a flexplate, I'm just amazed that the car still moved down the road!
brokeflex.jpg
 
What do you call a flex plat on vacation for a day, No flex I am on a break :glasses7: wow, sorry about the joke this morning :coffee2:
 
I had a 318 do that to me, piece flew off and I investigated and found this too. I suspect a early trans/convertor in a later large register crank. That was my deal...I needed TFpatty's bushing.
 
Maybe put in an after-market one built for racing (solid disk). The way it broke, it appears like brittle steel, not tough steel like a flexplate needs, but perhaps there is an axial mis-alignment between the engine block and tranny body that made it flex every rotation and thus fail from fatigue. I found the flexplate in our 3.8L Mopar engine cracked all around the bolt circle, and shifted 20 deg from the crank. That seems to be a common failure, probably due to poor steel.
 
We drove the thing with it making noise for three months. Back then, I took out the dust shield because I thought it was hitting. It got gradually louder and LOUDER but still ran fine!

I even drove it into the garage to take it out! When I took out the first TC bolt, I got an ear..Damn! The second bolt and I got ANOTHER EAR.. F#@k! The third bolt gave me the little piece. WTF???
The last bolt was still attached!
It's one for the history books for me..

I changed out the entire engine and trans because I took in a 67 parts car with a good running one. I now know there's nothing wrong the motor. It'll be a good spare.
 
What year motor and what year trans? post 67 motors had the larger register so a pre 68 small register trans would have had the potential to wobble around in there on every rotation. Solid B&M would not do that but is not really a flex plate either in a matter of technical speaking.
 
KA-BOOM! Never seen a Mopar,do that before.Used to the Chubbie's doing it.Drives you nuts.The damn sound is intermittent.
 
I have recently been educated about the 67 small snout trans thing when I was looking for a replacement for the Valiant so I checked it. The trans in this car was correct for a 72. Big snout. So that can't be what caused the problem.

Anyway the Valiant also had a cracked exhaust manifold, so I just pulled the engine and trans and replaced it with a good running 67 slant and 67 transmission. The engine has a good quiet exhaust manifold, the trans has never been off of it and the motor drove great down the road, so it was the easier way to go.
 
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