How to prevent Thrust Bearing failure

[meenkeene518]

AS the title says, my last motor failed because of a severely worn thrust bearing, what ways can i prevent this from happening again? i ran redline 20 50 oil and always had good pressure, but still the failure occurred, any info will be greatly appreciated.

Thanks,

 

[SouthernCal GN]

The oil (20W50) seems a bit thick, especially for this time of year. The thicker stuff will always give you good pressure readings, but just as important is flow thru the engine.

Who built the motor? How many miles on the engine before failure? Circumstances under which the engine failed?

In short, more info, please.

As to how to prevent thrust failure- all I can tell you is to build the engine to spec, making sure all clearances are within tolerance. Check and double check before bolting it together.

 

[Steve V]

What type of torque convertor? They can balloon and take out the bearing.

 

[chris718]

As stated clearances is the main thing.yes you can run the rods at .0009" to .0012" and the mains at .00112 to .0015".Just look at the factory specs.I really dont like when engine builders come up with their own oil clearances.This is one area where the factory specs rule.there is a crossdrill mod for the thrust bearing but its failure is almost always related to transmission issues or improper assembly /clearances.

 

[meenkeene518]

well the engine was a cheapo shortblock so it wasnt pro built, it blew up in the summer late fall so 20 50 was needed. we suspected alot of things but we think we ruled out the converter, bbut it needed a higher stall so were changing it anyways. the engine didnt fail, but it was about to, it was being inspected when they discovered the flywheel moved 1/4 inch. this time its going to be build with good components, so i just wanted to see if there was anything to do so i can keep this thing together and make it a reliable car. the mileage was approx 15000 ish i would say, and wasnt driven hard at all, never dragged, and only saw top power maybe 20% of the time rest was cruising

thanks for the info guys!!

 

[Chuck Leeper]

1.The part line edge of the brg can be chamfered a bit, to allow oil onto the contact surface.
2. The brg shell must be properly seated, before the main caps are torqued. [This gets 100% crank contact on both 1/2's of the brg face.]
3. The crank face must be flat, smooth, and perpendicular to the crank centerline. If you are using the old crank, this must be checked. [As should any other crank you may use.]

 

[turbodave231]

I don't think the type or weight of oil has much to do with a thrust bearing failure. You might want to check crankshaft end play before and after transmission installation. If the endplay changes after transmission installation, you have a problem.

I also like to center the torque converter rather than just bolting it to the flexplate. How do you do this? Before you install the torque converter bolts, push the converter all the way into the trans. Measure the distance between the converter and the flexplate. Install hardened washers or shims to take up half of the distance. BTW, if you can't measure a gap between the torque converter and flexplate, you have a problem.

I agree with Chris, transmission and/or torque converters cause most thrust brg failures.

 

[Ken H]

What transmission are you running? Has it been modified? What is the line pressure in the transmission?

This was the same problem a fast TSO contender was going thru. The converter checked out okay. Turns out the line pressures were too high. Contact someone like Lonnie at Extreme Automatics - he is on this BB - he can probably help you out with the correct line pressures the transmission should be at.

 

[turbofabricator]

I have found that the crank grinder is the usuall cause of thrust bearing failure. They always "true" the thrust surface by touching the side of the stone to the thrust surface. If you look closely at the thrust surface after a grind, the surface looks like a saw blade. I use 1500 grit sand paper to polish the saw teeth out of the thrust surface. I have, over the years, tried everythng to get more oil to the thrust to verifying the converter. The polishing of the thrust surface by hand has had the best results. It takes me about 1/2 hr of sanding to get it right. Then you must SMACK the crank snout backwards THEN the rear flange forwards with the thrust cap hand tight before torquing to seat the trust bearing.

 

[NJ Torque]

Locking converters hurt too...

 

[meenkeene518]

Thanks guys foir the needed info. also are there spec sheets as to which all engine parts need to be clearanced/ tolaranced into? that would be much appreciated!!

 

[turbodave231]

Ken is right on target with the comments about making sure the thrust surface is perfect and seating the thrust bearing before torquing the cap.

The clearances might be slightly different depending on the bearings and intended use. For a street engine, I set the rods and mains on the tight side of the factory specs. Pay close attention to the oil pump. blueprinting the pump and keeping clearances tight will ensure you have good oil pressure and oil flow to all the bearings.

 

[bison]

You need to test the cooler charge pressure on the transmission. Not the line pressure. It should not be over 50 psi.