Tranny/Transfer Case

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G

gibgoaz8

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Joined
Jan 17, 2009
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35
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108
Location
Gordon, Georgia
A rookie just looking for a little advice. I have a 1978 FJ40 everything original, 4 speed tranny with low and high transfer case. I have read somewhere that on some models of the FJ40 that the seal between the transfer case and the transmission would go bad and the oil in the transfer case would leak over into the transmission and actually come out of the tower on the transmission. This would also leave the transfer case without any oil and case damage. The cure for this was to drill both fill plugs, tap them and run a rubber hose from plug to plug to keep oil in the transfer case. I hope all of this makes sense. Any how, the question I have is: Do I need to drill the fill plugs on my tranny and transfer case and run this hose to keep this from happening to me, or, am I ok without doing this. Thanks for any response.:)
 
that kit has been around forever and then some.


you do not need to install it unless you have a seal leakage issue. the simplest way to check this is to pull the FILL plugs on both units. not the drain plugs. if a lot of excess fluid drains out of either fill plug, then you have a "swap" issue. otherwise you're just fine. make sure you keep the trans and t-case full and check the diffs while you're at it.

hth

georg @ valley hybrids
 
On 4 speeds it is often wear on the tranny output shaft splines that pumps gear lube from the transfer case into the tranny and not a worn seal. Lube seeps into the spline gaps and when you let off the gas, is squishes out; some going into the tranny side. I have replaced several seals and all of them transfered gear lube to the tranny from the transfer just like before. Replacing the worn shaft stops it.

Since virtually all 4speeds have worn output splines, the moral of the story is just install the hose and forget about the seal.
 
Gentlemen: Thanks for your advice and input. I think that I would feel much better if I just go ahead and run the bypass line. IH8Mud has been good to me. I appreciate all responses and help.
 
Small hijack -

Has anyone done the bypass hose on a stock PTO setup? The question was posed in the thread linked above but no answer.

I have a leak on a recently rebuilt tranny and transfer case that appears to be coming from b/w the two. I'd like to try the bypass hose to see if it remedies the leak but am not sure if having the PTO gearcase that bolts to the transfer case would be a problem casing the fluid exchange through the hose to not work the way it's intended.

Maybe just a longer hose is all that would be needed??

Anyone gone this route with a PTO setup?

-Jon
 
S4Cruiser said:
Small hijack -

Has anyone done the bypass hose on a stock PTO setup? The question was posed in the thread linked above but no answer.

I have a leak on a recently rebuilt tranny and transfer case that appears to be coming from b/w the two. I'd like to try the bypass hose to see if it remedies the leak but am not sure if having the PTO gearcase that bolts to the transfer case would be a problem casing the fluid exchange through the hose to not work the way it's intended.

Maybe just a longer hose is all that would be needed??

Anyone gone this route with a PTO setup?

-Jon
Click to expand...

the pto should not affect the fluid exchange either way since it shares the fluid with the t-case thru the opening in the side of the case. a longer bypass hose hould take care of any fluid exchange issues but i highly doubt that it will cure a leak between the trans and t-case.
i'd say you either have a leaky gasket ( due to a tear in the gasket or uneven mating surfaces ) or maybe the idler shaft o-ring got cut during installation. the t-case would have to be removed to fix the problem but it would be a good idea to figure out exactly where the leak is coming from before tearing into it.
 
Ok, really dumb question, but here goes....

Where is the fill plug on both the Transmission and Transfer Case on my 1981 Split Case?

I've drawn a yellow line where I believe the bypass kit would go, but I'm not 100% that I am correct.

Can anyone confirm?
DSC01047.webp
 
Last edited:
KY Longhunter said:
Ok, really dumb question, but here goes....

Where is the fill plug on both the Transmission and Transfer Case on my 1981 Split Case?

I've drawn a yellow line where I believe the bypass kit would go, but I'm not 100% that I am correct.

Can anyone confirm?
Click to expand...

You are correct!
 
Well, finally got my bypass hose made up.

Bought the flared fitting from McMaster-Carr just like BSEVANS and then took them to local hydraulics hose shop to make the rest.

Flared Fittings $22.00
Custom Hose $33.00

Total $55.00

Gosh. Only took me 9 months to complete. :rolleyes:
IMG_0494.webp
 
Question... for those that have used a barbed fitting how do you make it secure so it does not fall out of the drilled hole,currently I have drilled and taped out the filler plug but cannot find a brass fitting that has the same thread sizing and at the point were I am going to lathe down some tubing and thread it out the same as the plug I drilled and tapped out.
 
solder it--acid core solder will work fine.
 
This problem exist on all makes and models not just Toyota.....
 
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