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.