Thrust bearing
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Thrust bearing
I have a 1991 F-150, 302 V8, 5 speed standard transmission, ~148,000 miles. It has been diagnosed as having a worn thrust bearing. Is this common for this engine and transmission? I would assume that the engine has to come out to replace the bearing. Seems like there would be a lot of vehicles with standard transmissions that would have the same problem but I never hear about it. Just trying at this point to determine how common this problem is. Thanks.
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whats the symptoms?
that engine is arguable the most reliable engine in the world.
of course it is not immune to abuse from a teenage son or poor oiling habits like cheep filters and poor quality oil
a worn thrust bearing requires a complete rebuild of the bottom end and is part of the crank and rotating assm.
if the crank is damaged beyond 30-40 tho it may not be cost effective to repair it.
if it is toast i would swap it out for a mustang 5.0 engine with the f150 manifolds and fuel inj.
the mustang engine from 87-90 had all the goodies ford forgot to put in your truck engine like forged pistons,roller cam and 351 firing order.
it certainly wont preform like a mustang with the truck manifolds and computer programing but would be a noticeable difference im sure would be welcome.
that engine is arguable the most reliable engine in the world.
of course it is not immune to abuse from a teenage son or poor oiling habits like cheep filters and poor quality oil
a worn thrust bearing requires a complete rebuild of the bottom end and is part of the crank and rotating assm.
if the crank is damaged beyond 30-40 tho it may not be cost effective to repair it.
if it is toast i would swap it out for a mustang 5.0 engine with the f150 manifolds and fuel inj.
the mustang engine from 87-90 had all the goodies ford forgot to put in your truck engine like forged pistons,roller cam and 351 firing order.
it certainly wont preform like a mustang with the truck manifolds and computer programing but would be a noticeable difference im sure would be welcome.
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Thrust bearing
Symptoms; With the clutch down the fan belt squeeks,on a cold start the flywheel bumps the starter housing. The garage that did the diagnosis did not put a dial indicator on it and theydon't do work this major. I appreciate their honesty. The starter bumping makes me think there may be something loose on the clutch or flywheel but I'd bet I'm wishing there. A shop that I talked to about this said that I have a very good engine, as you said. The truck is in good shape thanks to a lifetime rustproofing warranty. I'm the only one who has driven it since it was new. Really don't want to buy a new truck.
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eww that does sound bad.
have someone watch the lower pully on the engine while you depress the clutch a few times in neutral no movement is good.
i would have to say your oil let you down on this one the crank actually rides on a film of oil and should not touch the bearing but letting out the clutch shocks the film of oil and if the oil is low quality it will push out and allow the crank to contact the thrust surface causing damage.
i better oil that contains zddp (10-30 rottela is a easy one to find) may help limp you by till you can save up for a rebuild or replacement engine
have someone watch the lower pully on the engine while you depress the clutch a few times in neutral no movement is good.
i would have to say your oil let you down on this one the crank actually rides on a film of oil and should not touch the bearing but letting out the clutch shocks the film of oil and if the oil is low quality it will push out and allow the crank to contact the thrust surface causing damage.
i better oil that contains zddp (10-30 rottela is a easy one to find) may help limp you by till you can save up for a rebuild or replacement engine
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Joined: Nov 2002
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From: Concord, NC
Sitting at stop lights with the clutch on the floor can decrease the life of the thrust bearing, along with cold startup. A friend of mine who owns a machine shop said it is not that uncommon on 5.0s, so I try to stay off the clutch as much as possible.
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Wow! I've always thrown her in neutral nut not for that reason. I did not know that.
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