thrust bearing wear

[flyinlow]

What would cause the thrust surfaces to wear .015" . The main and rod bearings look good.  (sbc sorry)

[Challenger340]

sbc
Insufficient End Thrust to begin with when Assembled ?
Lack of Oiling related to above ?
Poor Crank Regrind, with High Taper evident on the Journal ?

Other "in service" conditions, are related to Thrust applied to the Crank Mechanically while in operation, ie; Convertor Ballooning(heat), Clutch Pressures, etc., etc., etc., or ANYTHING else that could be PUSHING the Crank forward or back while running ?

If Aftermarket SCAT or EAGLE Cast Steel Crankshaft,
pay particular attention to the "finish" on the Crank Thrust Face, Campaign Changes were employed a coupla years back due to high numerical Thrust Failures Associated.
Same old story, finger Pointing both ways,
Clevitte Bearing and others, were blaming the Cranks Manu's, Crank Manu's were Blaming Brg Co's !
Nonetheless, it was the Thrust "Finish" as the culprit on those.

Hope this gives some ideas...

Bob out.

[elacruze]

What would cause the thrust surfaces to wear .015" . The main and rod bearings look good.  (sbc sorry)

If it's a clutch car, remember that all the force from the throwout bearing translates directly onto the thrust bearing, on the rear thrust face. If the engine has had a lot of stop-and-go traffic with a performance clutch, this is the most common result. Low RPM/oil pressure, high thrust pressure and lots of operation hours = worn face.
Auto trans, usually a converter issue doing the same thing, forward pressure. Can be a ballooned converter and don't forget that higher-than-stock pump pressure forces the converter into the thrust bearing just the same as a clutch.

I had a Chevy van w/350 in which the thrust was so badly worn that it had a knock when idling...had the knock for 20,000 miles. Upon rebuild I discovered that the knock was a crank weight tapping the block because there was so much clearance.

[flyinlow]

Thanks , maybe i should clarify. Total end play .030 . the thrust surfaces of the #5 main appear to be worn about .015 compaired to a new one.

2006 350 crate motor returned under warrenty for a noisy thrust bearing.  The short block was given to my son for a project car . It looks in good shape except

for the thrust bearing. Thinking about putting a new one in and a new pump and running it.

[elacruze]

...Thinking about putting a new one in and a new pump and running it.

That's just what I would do.