I have a 93 f150 with the 5.0 (302) in it. I’ve had issue in the past like rough idle and the truck shutting off while driving, it not wanting to start, front fuel tank back flowing into back tank, etc. Now I have an issue. The truck still runs and drives but after it runs I was hearing a grinding noise with white smoke coming out from under it. I got under the truck while it was running and figured out the noise was coming from the fly wheel. There’s a cover plate that bolts over the fly wheel that was making contact to the fly wheel causing it to smoke and make noise. So I thought I’d try to bend the cover out with a screwdriver and when I put the screwdriver in there and tried to pry the cover out the whole fly wheel slid back about 2 inches. That can’t be good. I popped the hood and discovered I can grab the lower crank pulley and slide it by hand back and forth about 2 inches back and then back to where it should be. I recently replaced the serpentine belt and the throttle position sensor. Could either of those repairs cause these issues? I haven’t ran the truck since noticing out of fear of ruining the motor completely. If those repairs had nothing to do with it what could be the cause? Is it the main bearing? If so should I replace the motor?
Thanks for any responses!
I recently replaced the serpentine belt and the throttle position sensor. Could either of those repairs cause these issues?
I don't see how. It sounds like either your thrust bearing is shot, or the crank journal that rides against it.
If those repairs had nothing to do with it what could be the cause? Is it the main bearing?
Over 30 years of wear and tear.
If so should I replace the motor?
Either that or overhaul it if you want to keep the truck.
Today I learned what crankshaft thrust bearings are thanks to @ChuckTobias. Thank you for sharing your knowledge.
@Rootertech the crankshaft moving 2 inches seems like a lot of movement. I'm surprised the counterweights on crankshaft can move that far without hitting something.
Here's a video showing that on some engines it's possible to replace the thrust bearings by dropping the oil pan. This probably only applies to engines that use washer type thrust bearings.
