Out for a drive in the 25-30 degree weather today. Had the fan pulley seize ... so just loosened the bracket to let the belt hang free. Cool enough to not worry. But this is the second time this has happened since I rebuilt this car. I drive it on a regular basis ... about 75 miles a week.
I never had this happen with my earlier T that had the smaller pulley and the grease fitting on the shaft nut. I used new bearings and shaft when I rebuilt this pulley ... adjusted the nut and felt washer to what I thought was right. Been using gear oil in the pulley and it does sling it out the seal. So, maybe do just I need to add oil more often .... or should I put a grease fitting in place of the brass plug and use bearing grease?
Suggest taking brg & shaft assembly apart before greasing to see how and where seizure occurred. Everything should fit w/o 'adjustment' for endplay. Maybe bushing flanges too thick, too many felts used, felt retainer washer going past step in shaft, bushings not pressed fully into hub? etc, respectfully, jb
I have been reading past threads on this topic ... so maybe I shouldn’t stir things up between the hub oilers and greasers.
I took the assembly apart the last time this happened about two months ago. Everything seemed to be ok, though there was some slight scoring of the bearings. I got it smooth and put it back together and it worked fine until this afternoon. I’m getting the sense that I simply just need to oil it more often.
I think it's pretty clear that the clearances are too small. If you found scoring and didn't increase the size, and it seized again, that would be a clue...what is the clearance at room temp?
And if you keep the smaller clearances, you definitely need to drop the viscosity of the oil down from gear oil...I assume is 90w?
It should be whatever you're using in the crankcase. Without oil grooves, you need pretty good clearance on bronze/brass to steel bearings with 90w...even with grooves, you need reasonable clearance
That fan's going at a good clip and you want hydro-dynamic lubrication and you're ending up with boundary lubrication
The last time I used Timesaver to lap in the shaft with the scored bearing. The shaft turned freely when I put it back together at ambient temperature .... 70 degrees. I’ll disassemble it tomorrow and go at it again. Then I’ll use regular motor oil and make sure it gets topped off once a week and see what happens.
Yeah, that's gonna be a c-l-o-s-e fit and I think motor oil is going to be your friend.
Most repro fan bushings have been plain brass for at least 25 years and this is the root of most “siezed fan bushing” problems. For the last 10 years or so I’ve made my own fan bearings from bronze and set them up with .002” clearance and haven’t had one seize up that I know of.