transmission knock

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Buck76Duster

Buck76Duster

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I have a 76 Duster 318 with a 3speed automatic. Today it started knocking loudly at idle in park an the knocking speeds up when I rev it gently. It continues in drive but goes away in reverse. My stethoscope is relatively quiet on the rear main, really loud on the bell housing (I know the front of an auto tyranny isn't really a bell housing), and then quieter again on the main body of the tyranny. I've been driving it for about 6 months and its always had a high speed (65 MPH+) vibration which seems common on he forum. Not sure if they're related. Any ideas would be appreciated.
 
First check the convertor to flex plate bolts. 2 other places the knock can come from... The neck on the torque converot that drives the from pump may be broken. That would feel like a drummer under the floor pan.
If it is just a audible knock taht you cant feel, its probably the thrust bearing in the enfine allowing too much crank movement. Good luck
 
My guess would be converter bolts also. If you have an inspection cover pull it off. The bolts will be right there. You should be able to turn the engine over using the bolts as well to get to all the bolts
 
Sounds like it could be torque convertor bolts,but if they,re tight you might have a cracked flexplate.Which you,ll have to pull the tranny to have a good look at it.The cracks are hard to see(hairline cracks).Good luck.
 
Thanks to all who responded. I checked the TC bolts via the inspection plate and they're all tight (I couldn't be that lucky). I'm going to tackle the flex plate ($8 at RockAuto) and hope that's it. I may try to get the rear main seal done too as long as I'm that far in. I'll post the results after pulling the tranny.
 
You may as well pull the engine to do the main seal. It's much easier on an engine stand than in the car.
 
Thanks for all the thoughts on my knock problem. Turned out to be the torque converter input collar. Half the collar had broken off at the drive notch for the tranny pump. It was still driveable, but I'm glad I parked it right away. Could have eaten up the front end of the tranny. I found a local shop that rebuilt the torque converter and put a new collar on it in one day for $85. That and half a bottle of Advil, and I'm back on the road. FYI... the guys who recommended against doing the rear main seal in car were right than they may have known. One of the pan bolts is hidden by the K-member so well that I couldn't even get a finger on it, let alone a wrench.
 
Since I was already that far in, I did the tranny mount, front and rear tranny seals, tranny filter and even the starter. It was the rear main seal on the crank I gave up on.
 
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