Failed thrust bearing.. Why?

[oestermarken]

When starting up the engine to get the car out off its winter storage, I heard a terrible knocking noise, it sounded like it came from the backend underneath the engine.
After some troubleshooting I decided to pull the oil pan, and then discovered the crank had a lot of endplay 0.14 inches
I then took out the thrust bearing, and could see a lot off material missing from the bearing and also the crank trust surface has a deep groove.

why has this happened? Is it just normal wear and a known issue or is there something internal / external pushing the crank forward and causes this failure?

The reason i ask is because, I want to know if there is something specific to look after, when I disassemble the engine.
It would be sad to have rebuild the engine and this happens again.

/Brian

[moparsr2ast]

  Generally a thrust bearing doesn't fail, at least to this extreme. It is one of 2 issues....either the crank has to much clearance intitially, causing it to rock back and forth in the saddle, and wearing out the thrust bearing in the process, or this is a manual trans car that has gone thru some very spirited driving. A rebuild shop will know if the crank is out of tolerance before it is final assembled. Good luck Brian

[Cooter]

When engine was rebuilt, there are TWO different thrust bearings. One is for like 1966-73 440's and one from like 1974-78 or something. You sure you/engine shop used the correct thrust bearing originally?

[oestermarken]

It's a Auto trans car with a 383.
I don't know if the engine has ever been rebuild, I guess I will find out when I get it out off the car and opened up 

[b5blue]

When engine was rebuilt, there are TWO different thrust bearings. One is for like 1966-73 440's and one from like 1974-78 or something. You sure you/engine shop used the correct thrust bearing originally?

So that would be forged or cast crank? 

[Challenger340]

In theory anyways, the Crank pretty much floats end to end in the Engine, nothing should push the Crank to cause a thrust failure ?
Unless,
something "pushes" the crank backwards from the Harmonic Balancer- DOUBTFULL, unless you have a prybar on it while running ?
or
something "pushes" the Crank from the rear, like a Balooning Torque Convertor, or in some Transmissions(non 727) excessive line pressure ?

Is it an old Engine ?
Maybe it was just time ?

A good tip when repairing, is to file a very small chamfer(.020") on the parting line of the Top(grooved)Thrust Bearing on only one side.
This allows a very small amount of the pressurized Oil to get OUT from the grooved upper bearing onto the Thrust Surfaces for added lubrication.
The above,
we found as a great cure with the sb Ferd 10.5" tire cars running HUGE Clutch Plate Pressures back when them Morons still ran sticks,
but,
works on the BB Mopars/HEMI's also.

Sorry for your loss, no fun in the spring when a guy wants to drive his car, feel for you my man.  

[John_Kunkel]

There is a not-too-common failure in the 727 TF that permits full line pressure into the converter that pushes the converter forward with 3-4 times more force than normal.

[oestermarken]

something "pushes" the Crank from the rear, like a Balooning Torque Convertor, or in some Transmissions(non 727) excessive line pressure ?

My thoughts has been on the transmission/converter, because I have sometimes experienced converter bolts have hit the gearbox shield, especially if I've been in a traffic jam for a long time and it then disappears after some time with normal driving.
I was told, that bad flow in the transmission oil cooler circuit, could push the converter forward. I don't know if this is true?

Is it an old Engine ?
Maybe it was just time ?

This is the original engine. I don't know if it ever has been opened, so maybe it's just time  

Sorry for your loss, no fun in the spring when a guy wants to drive his car, feel for you my man.  

This is really bad timing!! but isn't it allways  

[oestermarken]

There is a not-too-common failure in the 727 TF that permits full line pressure into the converter that pushes the converter forward with 3-4 times more force than normal.

Is this something I can check myself? I will hate to bolt a defective gearbox behind a rebuild engine..

/Brian