Rear Diff 1989 4x4

i see a nipple onthe top of the rear differencial, what is that for? to add fluid. what do i need to fill it? if i have a 1st gear squeak coming from the back should i add fluid? also i have lubed and sprayed the U joints just in front of it helped but very little. also i used some oil additive and it takes longer for it to warm up but it holds the pressure a little better. do you all recommend oil additives? also as per my previous thread the new rear shocks helped. thanks all.

The nipple is a pressure relief valve, not for filling which is done through the check plug on the side of the differential. If the rear end squeek is not coming from you're u-joints or companion flange dust shields then it could be your're differential bearing. This, however, you would hear in more than first gear. Check rear diff. adjusting nut. If it doesn't appear the staked portion of the nut is in the staking notch. Retorque the nut and check backlash ensuring the bearing is hand turnable, not binding and quiet. Oh, and before trying any of this, check your rear brakes and rear axle bearings first. The flange dust shields are an easy check as well.

if you go out under water alot your going to want to change the oil more frequently. i ran the breather all the way up to the bed of my truck so it can be submerged.



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