Front diff Pinion seal leak

[Lowwill]

My diff breather was completely frozen. At 1st I just noticed the axle seals leak which stopped by the way. Now I notice the front pinion seal is still dripping. I did kinda overfilled it when replacing fluid. Meaning I did it 1st thing in the morning and filled to it was pouring out. Figure if it was leaking anyway just add alittle more. Do I have to drop the whole diff if replacing? How much fluid do I have to lose till ruining the diff dry. Kinda just hoping it will stop like the axle seals did after a certain level of fluid drip out. 05 LX 146k miles thanks

 

[Rodger]

As you can see from my avatar I don't have a 100. but recently had my rear axle pinion seal changed - I didn't know how to do the preload so had it done professionally but the axle did not have to come out, just the prop removed.

Recently I had an interesting and very educational talk with Dave2000. I, undoubtedly like many of us, regularly crawl under with my grease gun and, in my ignorance, pumped loads of grease into the prop sliders. Now I learnt that this can create a hydraulic effect on the transfer box and on the axle pinion seals. Perhaps you do the same as I did and that could be the cause of the pinion seal leaking.

Regards,

Rodger

 

[Chris]

The pinion seal leaking is pretty common and can be due to one or two things. Regardless of the cause - for the second, either the metal has worn off the shaft or the material has worn off the lip of the seal. Or both. Causes?

Well, yes it can be the battering that Rodger mentioned, but it can also be lack of oil leading to a dry seal or excessive sand and dirt getting in past the dust shield slowly grinding things down. But it can also be due to wear in the outer pinion bearing. The inner bearing is a pretty huge affair but the outer isn't so big. If for any reason the pre load begins to reduce on the pinion (wear, no oil, brutal treatment) not only can the end float increase (the in and out movement) but also the bearing can effectively 'weather-vane' around in the bearing race. OK we're talking thou here but the seal is designed to have the shaft spinning centrally in it.

As the seal ages and hardens, that 'gyro' movement of the shaft will cause it to leak. I'm no expert on the 100 series front diff as it's a clamshell type but the principle is the same in terms of preloading the pinion. Whilst you should be able to rotate the flange back and forth about 5 mins on a clock face, there should be absolutely no up and down, side to side or in and out movement. If there is then your pinion really needs resetting. If not, then the seal can be hooked out and a new one driven in, resetting the pinion nut back to where it was originally staked.

 

[flint]

As said, if the pinion bearings do need replacing, then it is a diff out job. If no play other than rotational, then a paint or other marking on nut and shaft before undoing will help on reassembly.

 

[Chris]

Well you can actually replace pinion bearings in situ but you need a very special pullet. It's an SST from Toyota and the cheapest I have seen one was about £400. I've tried in vain to make one. You have to pull on the centre race of the bearing and there's barely any room between the rollers and the core to get a bite on it. Obviously the inner bearing is a diff out job.

 

[Lowwill]

Thanks for the replies