Had an oil pressure problem all of a sudden ranging from normal to 0. As I increased rpm
"slightly" the oil pressure moved toward 0 and let off the throttle it went back to normal. I removed the oil pump and screen and found the screen clogged real bad. Checked all of the main bearings/journals and they are good and within specs. But # 3 thrust bearing on one exterior side is pratcticlly gone. Cut open oil filter and found no metal particles. But in the pan found a piece of the # 3 bearing thrust side. My guess is this happened in short order and probably the screen plugged restricted oil circulation and somehow toasted the side of the bearing. I am replacing the oil screen and pump. Of course the cranshaft end play is way out.
Note, all of the bearings at journals are good, the engine does not have any noises...knocks etc., what are the opinions if I just replace the thrust bearing and if the end thrust clearance is ok, just leave the engine as is and drive it.?
This is the original 302FI in my F150 extended cab, never had any issues with oil/pressure before. Been using Mobil 1. About 125K on engine. Plan on keeping the truck (it is like new condition in and out) and later tear it down or buy a long block when I have the time to do it. I do not drive it much these days and figure at 62 years old I dont need another one until light years away. I have a 67 nova and some other toys I use more than the truck.
Thanks for your opinions.

 

If the rest of the bearings are within specs, just replace the thrust bearing. That seems like a pretty odd failure though. Is the truck a standard transmission? Excessive use of the clutch, by keeping it in for long periods like at red lights and such can supposedly cause the thrust bearing to wear heavily.

That's great that you stopped driving the truck right away when the problem came up. It appears that you saved the other bearings from getting ruined.

 

Its an automatic. Yeah, it baffles me why only the thrust bearing outer shim surface worn off??

 

On what are you basing your judgement tnat all your bearings are good except, of course, the thrust bearing? Are you inspecting them by sight or are you measuring and ensuring proper clearance?

 

measured them twice with the old plasti gage method. don't feel I need to go further with a micro since all journals appear well and even with a coin or finger nail there are no grooves. just really baffled how only the outer side shell of the thrust bearing wore out? thanks

 

talked to a mechanic and he pointed out that the auto trannie coverter may have balloon or the pressure within the trannie pump may be excessive,resulting in pushing the crank forward against bearing shim shoulder.???

 

The defective convertor sounds reasonable.