Small Block Mopar Thrust Bearing issue

[Ken Etter]

As said in an earlier post check the back of the crank. I have had this issue with two different cast cranks. The cranks werent machined deep enough. Inspect it with a light and see if there are any contact points.Something I also do is drill a small hole through the bearing into the main bearing oil hole to provide positive oiling to the thrust. Good luck.

[Mopar Mike]

Originally Posted by Ken Etter

As said in an earlier post check the back of the crank. I have had this issue with two different cast cranks. The cranks werent machined deep enough. Inspect it with a light and see if there are any contact points.Something I also do is drill a small hole through the bearing into the main bearing oil hole to provide positive oiling to the thrust. Good luck.

Ken,
Thanks for the input. Will check the crank again.
Mike

[Mopar Mike]

Originally Posted by gmonde

do you use a two step ????,also cold runs with thick oil will wipe out the thrust ,,there is a procedure you can do to help this gmonde

gmonde, not using a two step. Only the rearward side of the thrust bearing is being damaged. Thanks for the response.
Mike

[Mopar Mike]

Originally Posted by Michael Beard

Converter ballooning, had it happen even on a low 12-sec bracket car. Had too much line pressure in the valve body at the time, too... no idea if that had any part in it.

Mike,
The converter is due for a freshening up and we were planning on sending it out anyways. Thanks for the response.
Mike

[Mopar Mike]

Originally Posted by magnumv8

What I have seen that has caused excessive thrust clearance is misaligned pulleys on the front of the engine....this creates pressure forward or rearward on the crank causing either the bearing or crank flange to wear....it takes very little misalignment to create this internal drag especially with a V-belt set up.....


D L Rambo.....

D L Rambo, Will check that out also. Thanks for the response.
Mike

[Mopar Mike]

Originally Posted by mopar

check the back of the crank where the pilot bearing would be. have found that to be the problem even with convertor spinning free. do not have any measurements.


Ron Waters s/st 1346

Ron, will check the crank again. Thanks,
Mike

[Mopar Mike]

Originally Posted by Peter Ash

If any part needs surface lapping. It should be done in a figure "8" pattern on a surface plate(glass or a highly finished checkerboard steel lapping plate). This is how I was taught when we used to rebuild fuel injection components.

Peter

Peter, Thanks.
Mike

[Mopar Mike]

Originally Posted by Mopar Mike

I haven’t ever seen this before, but the crank looks to be pushed forward from the torque converter and is wearing down the thrust bearing. This is a cast crank 340; there is about a 1/8 to 3/16 gap unbolted between flex plate and converter. Spins freely, and moves back and forth easily. The forged crank 340 has no problem with same Trans and converter. Any ideas?? Thanks,
Mike

Thanks to all that have replied, I was thinking converter and will look closer at other possibilities.
Mike

[Henry S]

There is a lot of info on the net. Do a search for thrust bearing problems. and look for the AERA paper on diagnosis and symptoms. most likely restricted coolers or cooler lines cause the torque converter to be pushed forward causing thrust problems. check your cooler line pressure.

[GTX JOHN]

I had problem with imput shaft on my 904 being significantly Bent.....Also I would dial indicate end of crank flange.....I have seen Cast small block cranks becoming seriously bent.