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Home » Public Forums » GMCnet » 455 bad thrust bearing (Need input on why my 455 failed after 80,000mi)
455 bad thrust bearing [message #371491] Thu, 12 October 2023 14:30 Go to next message
rgogan is currently offline  rgogan   United States
Messages: 82
Registered: February 2004
Location: Milwaukee, WI
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My rebuilt 455 was leaking through the rear main seal. Removing the inspection cover on the transmission allowed me to push the torque converter about a .25 inch forward and this crank movement was also seen of course at the harmonic balancer. Engine died with a bad connecting rod about 200mi later.
What causes a thrust bearing to fail so badly? I received the following answers:

1) poorly machined crank
2) bearings not lining up with the oil supply hole in the block
3) misaligned v belt accessories
4) a torque converter which is bulging the flywheel forward or has excessive pressure from a restriction in the transmission cooler lines.

I can understand the first 3 but am puzzled about how high torque converter pressure could damage the trust bearing. Even if it caused the converter to bulge, there is plenty of play behind the torque converter before it would push the flywheel forward.

Any thoughts
Re: 455 bad thrust bearing [message #371492 is a reply to message #371491] Fri, 13 October 2023 14:55 Go to previous messageGo to next message
bwevers is currently offline  bwevers   United States
Messages: 597
Registered: October 2010
Location: San Jose
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Senior Member
Saw this article about excessive transmission pressure:
http://gmcws.org/techcenter/99-12tc27.html

Good Luck with your rebuild


Bill Wevers GMC49ers, GMC Western States 1975 Glenbrook - Manny Powerdrive, OneTon 455 F Block, G heads San Jose
Re: 455 bad thrust bearing [message #371498 is a reply to message #371491] Sun, 22 October 2023 11:38 Go to previous message
roy1 is currently offline  roy1   Canada
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
Senior Member
Probably not your problem but I lost a thrust bearing due to a shift kit in the transmission . It was real hard on the crank shaft and wiped out the bearings. Had manny remove the shift kit while I rebuilt the engine.

Roy Keen Minden,NV 76 X Glenbrook
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