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I have a 1991 Full size Bronco with the 5.8 v8 in it. I had brought it to my mechanic because it started smoking really bad. Coming from my engine bay, under my truck, and through my vents. ( I knew it wasn't my valve cover gaskets, I had them replaced a few months back) The smoke would start when I drove up or down a hill or any longer than like 15/20 mins.....but never if it just sat and ran. I had to physically be driving it. I was told that it was my rear main seal and the reason it was smoking like that is because oil was hitting my exhaust. Well anyway....my mechanic called me to tell me yesterday that he had put in a new rear main seal and a new oil pan gasket but there was a problem.......he told me that my crankshaft bearings were bad and that it might continue to leak oil and smoke because it had "so much play in the crankshaft". Well its still smoking and leaking ......I was told by a few people to get a second opinion because my engine would knock if it was crankshaft bearings..... my engine is fine no odd sounds. Could it still be that problem with no noise? He recommended a rebuild or new motor. I'm a single mother and it would take me a good amount of time to save up what it would cost to get that kind of work done. I really don't want to get rid of my truck I love it.......just some advice on what to do. Any replies would be greatly appreciated.
 

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if the thrust bearings were worn, it may not have any noise ,just too much end float

a hot oil pressure test could give you an indication of general condition of engine bearings
 

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a spun bearing would cause a knocking noise. that bearing would have no oil and would start flaking away from heat. this wont cause an oil leaking problem. once a bearing is spun you have minutes left till the engine seizes.

however worn bearings wont cause a noise. but a worn bearing wont cause leaking either unless it was soo worn out that the crankshaft was sagging making to top of the seals not seal. but id imagine if they were that bad you woukld have little/no oil pressure.

I suppose worn thrush bearing could make a oil leak in a very severe case but don't see it likely. if the crank had enough play the seals would probably move onto a non worn out section of the crank where there wouldn't be a wear mark on it from the old seal.



depending on where the oil is getting burned at would help determine the problem. if the oil is burning at where the drivers side exhaust going under between the engine and tranny then it might be the rear main seal or oil pan gasket still. but it could be the valve cover gaskets leaking again, intake manifold gasket, camshaft end plug. if the oil is burning on a exhaust manifold on either side of the engine its most likely the valve cover gasket. if the oil is coming from in front of the engine it could also be the front main seal or timing chain cover gasket.

if the old seal left a groove in the crankshaft, which does happen over time, even a new seal can have issues. when this happens, they make a sleeve that goes around the crankshaft so the new seal can have a good seal.

groove from seal


how it should look
 

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Strange that he would do the job then after he did ti tell you the bearings are bad.

Sounds like a shadey mechanic to me.
 

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bad bearings = knocking sounds.

I've had engines that knocked REALLY bad and had horrible bearings, and they didn't leak oil.

the mechanic sucks and he's using this either as an excuse for failing to fix the oil leak, or an excuse to sell you a bunch of work you don't need (new/rebuilt engine)

Oh, and crank bearings generally don't go bad (within the first 400k miles or so) unless you either
1. never change the oil.
2. run it out of oil.

I'd go to another shop.
It can be hard to find a good shop, of the ones I've used, nearly all have either had poor workmanship, or been dishonest (or both).

What part of the country are you in?
 

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Strange that he would do the job then after he did ti tell you the bearings are bad.

Sounds like a shadey mechanic to me.
I agree with ^^^^. The mechanic should have informed you of the other issues when they were discovered.
 

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Spend your money on a compression check and oil pressure check to determine the condition of the motor. From this information you can assess the future need to rebuild/replace the motor.
 

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the mechanic sucks and he's using this either as an excuse for failing to fix the oil leak
This was my thought. I'm guessing he thought there was a good chance that he'd botched the seal repair and went into preventive cover-thy-a$$ mode ahead of time.
 

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Discussion Starter #10
Just wanted to thank everyone for their replies!
! They were very helpful. I got a second opinion and was told my engine was pretty shot. I was just shy of 300,000 miles...... :/ I think I'm going to hold on to my truck and get a rebuild done. Already did the transmission about 4 months ago.
 
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