My pinion seal started leaking, installed a new seal and a month later it started leaking again, now I'm starting to feel some vibration at steady speeds, I suspect a bad pinion bearing (already changed U-joints). It's a 92 F-150 XLT Lariat 4x4, 5.0 EFI, 4 speed w/granny, anti lock rear breaks. I run 900x16 directionals, 1-1/2 inch lift in the front. Does anyone have any advise on this job, it's one that I have never attempted before.

 

I posted the wrong year for my 4x4, it's a 1989, I must have been thinking of my mother's 92 flare side that I recently replaced a window motor in... I'm also doing a 300 to 302 swap in a 85 F-150 for my son, you should see me when I go to the parts store trying to remember which one I'm buying for.

 

My best friend used to have an F-150 4x4 with a simmilar problem. I don't know if you are having this problem also, but he had to frequently change his U joints. He discovered that his driveshaft was bent years later (probably bent it off road) after having re-worked everything else. If you start having U joint problems your driveshaft may be out of balance or slightly bent. If the U joints aren't showing any signs of wear than I would say that it is definitely your Pinion bearing. Changing that is sort of involved, but you can probably do it yourself in one day. If you have already changed the seal you probably know what kind of timeline & effort you will be looking at.

 

Andy ,
When you replace the pinion seal , its very important that you set the preload on the bearing very close to what it was before the replacment . Also check the vent hose for blockage ....99% of all pinion seal leaks are caused by the vent hose being plugged up . If you have a vibration , its possible you didnt get the proper preload on the bearing .
Paul