Transfer case leak

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Mar 17, 2010 | 05:40 PM

mileswacker

Thread Starter

New User

Joined: Mar 2010

Posts: 5

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Transfer case leak

I have a leak from rear of my transfer case, I believe it is a NP205.

Truck: 77 F-150 Custom, 351 W, 4-speed Manual.

What type of gear oil should I use for this transfer case? And, where is the leak coming is it a seal or from the plug/vent on top?

http://i793.photobucket.com/albums/y...d/IMG_0471.jpg

http://i793.photobucket.com/albums/y...d/IMG_0473.jpg

http://i793.photobucket.com/albums/yy217/1977Ford/IMG_0474.jpg

Thanks!

Mar 17, 2010 | 05:42 PM

82ford302

Senior User

Joined: Apr 2006

Posts: 332

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From: horton, ks

from the pics it looks like its leaking from the vent. check your fluid level to make sure it isnt over full.

Mar 17, 2010 | 08:50 PM

4x4 Bart

Fleet Mechanic

Joined: Feb 2007

Posts: 1,326

Likes: 48

From: Middle TN

Mine looks exactly like yours and I think it leaks out the vent too. It's at the correct level so I don't have a clue why it comes out the vent. It is filled with 90w but a multigrade would be better for winter weather.

Dec 14, 2016 | 10:06 PM

feeble

Freshman User

Joined: Jun 2008

Posts: 35

Likes: 1

Bump. Same issue, leaking from the vent tube.

The NP205 fluid level hasn't been touched in almost two years when it was changed by the previous owner. I have a heated garage and it is damn cold this week.

Drove the truck to work yesterday, just over a mile and home after work, no issues, parked in garage.

Today before going to work I notice a 6" diameter puddle of clean gear oil on the garage floor under the truck, looks like it came from the vent on the NP205. I drove it to work and looked where I parked yesterday, pavement is dry. Drive home for lunch, put it in the garage and rode back to work with my wife (we work at the same place).

Come home tonight after work, truck been siting in the heated garage for the afternoon and there is another puddle on the floor. Stuck my phone up there and it is obviously leaking from the vent.

Suggestions?

Dec 14, 2016 | 10:19 PM

ZarK-eh

Elder User

Joined: Sep 2014

Posts: 862

Likes: 7

From: like subarctic, brrr man!

Those are some weird symptoms... Maybe the case is pressurized somehow from the cold to warm cycle? but.. then how would the oil get there... hmm.. *shrugs* ah goot nuttin'!

But, what about sticking a hose on it? or replace that vent with a nipple (snickers) and run that way up high, like the axle vent is done?

Dec 14, 2016 | 11:42 PM

77&79F250

Moderator & parts slinger

Joined: Feb 2007

Posts: 50,247

Likes: 5,813

From: S/W Missouri, Polk county

Look on the front of the xfer case for a silver/blur tag to ID it. Have you pulled the upper fill cap and made sure it is not way OVER full? Should uses 80/90 gear lube.

NP205 Rebuild Guide

NP205 New Process Transfer Case Diagrams and Information

Offroad Design - Complete Rebuilt NP205, NP203 transfer Cases

Attached Images

Dec 15, 2016 | 04:03 PM

moose4x4

FTE Emeritus

Joined: Jan 2006

Posts: 2,288

Likes: 200

From: springfield Missouri area

The only thing I can think of that would cause that if the fluid level is correct and the vent is breathing correctly. Where the rear housing bolts to the main case there is a small cutout for an oil drain back. It could be plugged up some how. Too much silicone from previous repair or just gunk from old oil. I ran in the rivers and creeks a lot so I ran my vent way up high. Be sure to check tranny level. The transfer case should be over full if tranny was leaking into transfer case.