G'day guys - 2001 F250 7.3L 280k miles. Truck is new to me in the last 6 weeks. Was driving out to Glenwood Springs last night and I got a wierd rear end vibration between 79 and 81 mph - couldn't say if it's a new vibration as haven't had the truck long enough. It's sort of still there over 81 but less obvious than bang on 80. Whilst the vibration was there I caught a slight dip in the road that caused a grinding noise to accompany the vibration - I'm guessing because something's was getting extra loading on the upside of the dip.

I'm away from home until Monday so my options are a bit limited, however while crawling around in the dark last night pushing and shoving stuff to see if anything was loose I noticed a couple of things:

Minor leak from pinion seal - but it has flung some spots of oil.
Drive shaft 'centre bearing'(? U shaped attachment on drive shaft to chassis with rubber bearing?) has play I can push the drive shaft at least a 1/4" with my hand and it seems a little sloppy but I'm no mechanic.

I'm going to check transmission fluid level today and top up if required and check the magnets, such that I can limp home as necessary avoiding 80 and get the diff checked and pinion seal replaced.

Does the drive shaft bearing need changing or should it have that much play?

Thoughts comments appreciated - I'm assuming it's LSD on the rear? - cheers guys

 

I've never seen an old truck with a good D/S hanger or center support bearing yet. It may not be the cause of your problem - but it needs replaced. 250k+? Uh, yeah.

 

Is it an easy job?

 

It's not real bad. Seems to me a bearing press will help, though. Take it to a driveline shop and have them do all the u-joints as well, check for straightness of the driveshaft itself and I think they can do a good job balancing the whole thing.

 

That is not leaking.


Check tires and ujoints.

 

Nice it's not, that's the centre bearing, the pinion seal has the leak. Didn't post photo yet, but I can. Just had 4 new tyres all round and balanced - checked the weights they're all still there. Doesn't mean they didn't mess up tho eh?

 

 

Center support or hanger bearings don't ever leak. They just get loosey goosey and vibration levels go way up. Replace it.

 

I would not be concerned about that bit of leak. Clean it off and watch.


Remove the driveshaft and look at the ujoints. Just because you can't feel slop when it installed does not mean they are good. I bet you find one or more seized.

 

noticed your thread message, I f it was me I would check your u-joint, when you turn the driveshaft with your hand, there shouldn't be any play or movement in the u-joint, if you notice either one, I would replace the u-joint,
also do you know how many miles are on the u-joint could it be original, if so based on mileage install new one, also based on what you said your symptoms
were I would recommend doing a visual inspection of the worm gears in the rear end, hope that this info is helpful to your situation,

thanks moreland66

 

Thanks dude, there doesn't seem to be any play in the u joints, and I can't say for sure wether they're original - wouldn't surprise me if they were!! I'll get on it with the work gear and try do it this week!!

 

So the diff plug doesn't seem too bad! Oil was just below the full plug hole which is encouraging. Checked drive shaft this morning and there's no play in u joints. Edge of centre bearing hangar isn't uniform I noticed, like it may have had some rubbing. Drive shaft out tomorrow for new bearing and balance and then test run. Rear wheels off for re-balance as well, even though the tires only been on 2 weeks.

 

I mentioned up there /\ checking ujoints in the vehicle is impossible unless they are falling apart. No wiggle does not mean they are good. One or more could be seized.

 

Ahh ok gotcha, DS is coming off tomorrow for new centre bearing I'll check them out and see what's what - thanks again

 

Centre bearing changed out, new U joints and driveshaft balanced, have two fastners to replace on the rear yoke? to driveshaft and then i can take it for a run and see whats what!