Oil Leaks

[Fastbackin1970]

I have oil leaking out of the back of the transmission where the driveshaft hooks up. It's also leaking out of the rear diff where the driveshaft hooks up. How big a deal is it to fix the leaks?

[FORDification]

The transmission output shaft seal is very easy....just remove the driveshaft, pop the seal out and tap another in.

The rearend's pinion seal is a bit more involved, mainly cause a lot of folks don't have the tools necessary to break the pinion nut loose and retighten it. (They're on pretty tight!) Also, the pinion is adjusted using crush sleeves for pinion bearing preload. Once you remove the pinion, the preload is gone. If you overtighten the nut, you'll ruin the crush sleeve and have to start over and replace it again.

[Fastbackin1970]

Do you need to drain the transmission fluid?

[FORDification]

No, it's not necessary. A little might seep out, but not enough to warrant the hassle of dropping the pan to drain the fluid.

[James72]

This may sound a little caveman but I've used a long breaker bar on the yolk nut and pushed the truck by hand (or driven a 4x4 slowly) when the bar is forced to the ground the pinion nut will break loose, Use the buddy system on this one cause if you go the wrong way....
That'll get it appart anyway.

[Fastbackin1970]

Have oil dripping out of the rear main seal, the end of the transmission and the diff now.

[MaxKlinger]

How fast is it leaking?

My '83 leaked everything from everywhere. I just kept a gallon of every fluid behind the seat and learned to check regularly. It's really easy to check and fill a 9" rear. Also, remember that a small drop of diff oil makes a big puddle, it's usually not as bad as you'd think.

[390Nut]

How fast is it leaking?

Also, remember that a small drop of diff oil makes a big puddle, it's usually not as bad as you'd think.

That's what I thought too, until I burned up the bearings in my rear differential. Still had roughly a 1/3rd of the gear oil it was supposed to have in there. A lot more gear oil gets slung out when the gears start turning, believe me.

One way to replace the pinion seal without tearing it apart and resetting everything is to get a spacer with shims, instead of a crush sleeve. Simply measure the crush sleeve with a micrometer (or ask your friendly neighborhood mechanic to do it for you!) and measure out your spacer with the correct shims to the exact same thing. Simply reinstall and torque down the pinion nut.

I'm not 100% sure, but I believe you'll need to pull the pinion cover to do this, so you'll need that gasket to reseal it. Keep in mind the pinion cover MAY have shims as well. They will need to go back in to do it right.

Not the best/proper way, but it does work.

http://completeoffroad.com/i-122804-sol ... ollar.html

[fordman]

do you need a traveling mecannic or can you pull the engine or trans by yourself. thats the only way to fix the rear main seal on the engine. however are you sure its the rear main seal and not the rear of the intake leaking? the trans seal is a easy 30 minute fix at the most. remove the driveshaft remove the trans yoke pop the old seal out put the new seal in and put it all back togehter.