1987 T-Case Oil Going Into Tranny

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A friend has a 1987 FJ60, when we check the t-case oil, it is low.

After driving a while, we recheck it and it is low again, but tranny overfilled. No major external leaks.

Is there a seal between the t-case and tranny that may have failed allowing the oil transfer?
 

g-man

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yes there is a seal. Quick fix is a bypass line that goes from the transmission fill plug to the t'case fill plug. this will help even out the gear oil but it will probably still be off from what normal levels are supposed to be. Correct fix is to pull the transfer case and rebuild it and replace the seal.
 

Godwin

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When you replace the seal use one from a FJ62 because it has a double lip instead of single. Part # for the seal

9031648003​

 
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Thanks, nice idea for the hose between the fill holes, but agree we will pull the t-case and replace the seal. Winter project
You might as well rebuild the t case while you have everything pulled apart. The kit costs $245 or there abouts and if you get it all apart you’ll feel silly if you don’t have all new bearings and whatnot to go back together.
 

OSS

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Or remove the skid plate permanently to get it out of the way (if you want), then check the oil levels frequently and adjust as needed.
I used that method for 15 years (but kept the skid plate on). Kinda a hassle but after a while you get to know how fast the leak is.

I'm not a fan of using that bypass hose at all. Gives a false sense of security because oil can migrate past the seal in either direction, and when it starts flowing from transmission to transfer, that hose will do nothing, but you think it will - and the transmission will run low on oil and you'll never check it - and tranny can get damaged.
 
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Or remove the skid plate permanently to get it out of the way (if you want), then check the oil levels frequently and adjust as needed.
I used that method for 15 years (but kept the skid plate on). Kinda a hassle but after a while you get to know how fast the leak is.

I'm not a fan of using that bypass hose at all. Gives a false sense of security because oil can migrate past the seal in either direction, and when it starts flowing from transmission to transfer, that hose will do nothing, but you think it will - and the transmission will run low on oil and you'll never check it - and tranny can get damaged.
Just drop it and fix it correctly. It’s a lot of labor, but it’s an enexpensive chore when compared to a toasted transmission/t case.
 

OSS

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This is the pesky varmit that's leaking
image.jpeg
 

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