Hi,

This is the king of dumb questions, but I'm ignorant on 4x4 vehicles and I need educated.

I have a 77 F150, from researching the web, I've determined it has a NP205 transfer case.

I want to add some oil to it, since it is leaking around the front driveshaft seal.

There are 2 square headed plugs on the rear of the transfer case. They look like filler/drain plugs to me. One is about midway down the transfer case, and the other is near the bottom.

To fill the transfer case to the proper capacity, do I just remove the top plug and fill it to that level (like you'd fill a Ford 9 inch rear end)?

Also, do I use 80 w 90 oil?

And finally, how hard is it to replace that bad seal at the front of the tranfer case? It is the one where the front driveshaft yoke comes out of the case.

Thanks for your time,
John Thomas

 

Not a dumb question at all. You are correct in your assumtion about the two sqare plugs. The bottom one is the drain, and the top the filler. Yes, open the top and fill it to that point with 80w or 90w gear oil. Not ATF, Not motor oil. GEAR OIL. But before you fill it up, change the front output seal. First take out the front drive shaft, next remove the yolk nut on the transfer case front output yolk. (The piece on the transfer case you just took the driveshaft off of. (just in case)) Next remove the 5 or 6 (can't remember) bolts that hold on the seal housing and it should come right off. Now you can work with it on a bench. Take a large socket or piece of pipe and tap the seal out. Take it with you to the parts store for comparison. Tap the new seal in. Put some black RTV on the transfer case re install the seal housing, (make sure it is clocked correctly) Install the output yolk with a little oil on it to make a good seal with the new seal. Tighten the yolk nut down. (the easiest way to do it is with an impact wrench. There is no specific torque it needs to be. I take them on and off with an impact wrench. But thats just my opinion.) Reinstall the drive shaft, fill the transfer case and you should be good to go. Hope that helps.

RubberDuck

 

Yea, I just replaced the front yoke seal on my NP205 a few weeks ago. However I didn't pull the seal housing. I managed to yank the old seal out with a seal puller. You know, the kind with 2 hooks you can pick up just about anywhere.

I used the impact to cinch up the yoke too. I've got about 500 miles on it and have been in 4wd a few times. So far so good.

 

My seals are leaking front and rear, can i do this seal repair with the transfer case still in the truck? I dont have a jack and all that readily available, lol.