Help with leak identification

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Feb 24, 2005
So my local TLCA group is going to get together and help me plug some leaks in my drivetrain. First I want to figure out what is leaking to get grasp on the scope of work involved. This will be a one day wrench fest and I would like to have it driveable at the end of the day.
First let me say that every part of the drive train leaks, pics to follow. I know the front knuckles leak, so a birf rebuild is going to happen. I know the oil pan leaks, not sure about the front or rear seal though. Also the trans/TC are covered and the rear pinion leaks.
Front oil pan leak.jpg

front diff leak.jpg

rear engine oil leak.jpg

side view trans to TC leak.jpg

underneath trans to TC leak.jpg
A few more...

underneath rear oil pan leak.jpg

rear pinion leak.jpg

So help me get a parts list going. If the rear main seal is leaking I understand its very easy to replace with the trans/TC out. So if we are going to pull the trans we might as well replace all of those seals as well.
To replace the rear pinion seal the 3rd member has to come out and we will need to completely set up the rear gear again?? Is that correct? I searched the 40 section for 3rd member rebuild info and could not find much.

Thanks for your help.
Brad - did you get your leaks all figured out?

I just replaced the RMS, hoping to resolve an underside oil leak. Also replaced the oil pan & gasket - only to find the leak is still occurring at the rear of the oil pan gasket. I'm pretty sure that I overtightnened the pan to the block, and that is causing my issue. Luckily I just finished the job today, so I'm gonna drain - save the oil - and remove and reinstall the oil pan & gasket - and refill on Monday.
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The pinion seal can be changed without a complete tear down.But I have to warn you it it not for a novice.
By removing the big nut at the pinion yoke, you can gently tap the yoke on the back side with a hammer to work it off of the pinion shaft.
Then you can pry the old seal.
For tapping the new seal in they make a special tool, but if you can find a piece of black pipe or a big socket that fits the flat metal portion of the seal well, you can tap the new seal in. Just be careful to keep in straight while knocking it in.
Next is to clean the spline and seal surface of the pinion yoke and scuff it up a bit with a scotch brite pad or steel wool.Apply just a small amount of chassis grease onto the lip of seal (so it has some lubrication), apply a thin smear of rtv sealer on the spline surface of the yoke( so it seals between the splines) ,then gently tap the yoke back onto the pinion shaft. Apply some thread locking compound to the pinion nut. Install the washer and nut.

Now the hard part..
Tightening the nut is where you can get in trouble, Tightening the nut adjusts the pre load for the pinion bearings. Too tight= BAD Too loose= Just as BAD. The books will tell you 15-20 in /lbs using a needle style torque wrench, but that is with just the pinion gear installed.That's not going to work if the diff is all together.
This is what works for me..
Remove the wheels and drums so that the axles can spin freely. Then hold the yoke and tighten the pinion nut slowly and feel the movement of the pinion shaft. ( you can use a big pipe wrench to clamp onto the yoke to hold it in place, just be careful not to bend anything up)You will feel that the play will eventually start to tighten up to where you have zero play . At that point you should be able to turn the pinion shaft and it should feel smooth, with no lumpy or binding feel.
Recheck for any free play, if you need to tighten a bit more that's ok. just don't over tighten.
Once you have zero free play ,tighten the nut another 15-20 degrees to where you just feel just a little bit of drag.That's the pre load you need to keep the bearings happy.
Lastly, If your not comfortable doing this, by all means take it to someone with the skills to make sure its done right.
There's no disgrace in calling in for back up... Good Luck !!!

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