Hi guys
my 86 makes a humming sound after its been driven for say 30 miles ..does not do this on short runs. It sounds like the rear end ..I jacked it up and greased /inspected looking for u-joint etc ...48,000 mile car...I noticed seal on differential was wet .thot it might be low on oil ... my theory is its low and with travel and speed it slings oil outward. When stopped it settles back down .???????
here's the rub I can see the fill plug but cant get a wrench on it let alone get it out to top it up.
any tips .. ?and no I don't want to drop the rear end to put 90wt in it.

 

It's a PITA but if you situate yourself at the right angle, lean on one elbow, squint with one eye, have an assortment of wrenches, AND hold your tongue just right you CAN remove the filler plug . I know cuz I've done it a few times.

Or.....if you're more interested in results than gymnastics.....

Remove the tie plate (only, what it is? 22 bolts?) and you can reach the plug quite easily.

Cheers
DD

 

And, as I recall, the filler cap is similar if not to a plumbing cap. Either a female square or a male square for the wrench to attach to.


In olden days, we had a tool for the female version. A short beam with four squares on each end, each a different shape.


Now, I think a socket drive fits, either 1/2" ort 3/8", I don't remember.


There are four sided sockets, but usually a Ccrescent wrench will get the male version.


Gear lube is messy, second only to ATF!!










Carl

 

As I'll have it up on jack stands anyway, and husband has a mostly new battery wrattle wrench, I'll do the 22 bolts.

Mine isn't making any noise yet but I just looked to know the subject, and I see moist dust at the seals so it's probably time. I also see a tiny drop of brake fluid on one of the rear calipers! Maybe I should just drop the IRS and fix it all. THAT will be an adventure, like I have nothing else to do with it this Winter! It was last done probably in 1986 at the time of the conversion.
(';')

 

Thanks for the tip. Yes removing the plate was relatively easy. Used 3/8 air wrench . Remember to wear ur latex gloves. The plug was 9/16 and square . I guess if u had a 5/8 on a swivel and some extensions it could be taken out without removing plate but I don't know how I'd to put it back.
Puting in oil was solved by using an empty "slime" pump. U. Know the stuff u put in tires to fix and prevent flats. I get mine in gallon jugs that have a pump and little hose. Fortunately I had saved one . The 90 wt is a little thicker but it will slowly pump it . Put a quart in my 64 Chevy truck but only a cup or so in jag.
May still be hunting odd HUM noise after a run.

 

Kind of an odd statement...presumes someone here would suggest that.

Kind of more odd that you did end up putting 90wt, albeit just a little.


In any case... your car has low miles and given it's age that suggests it has sat idle for long periods of time. Diff's are vented and can collect moisture. Over extended periods of time the diff oil settles, and the atmospheric moisture can degrade the top half of the output shaft side bearings. These bearings take a beating and are a wear item because they are used to propel the vehicle and act as the upper control arm bushing. You should disconnect the side drive shafts and test the wheels bearings and u-joints for notchyness and feel by hand if, they're ok, then looks like you'll have to tear into the diff as a unit. The rear diff assembly is one of the most complex and amazing parts of the Jag and rebuilding one is a right of passage.