? strange hissing noise while checking transfer gear oil level

Been keeping a monitor on odd transfer case and or manual transmission weep...
Each time I have checked levels in the past 5k miles they have both been full as full can be

After a lengthy 150 mile run the other day I cracked the transfer fill plug and heard a noticeable hissing as I was unscrewing the plug. Hissing stopped and then gear oil came out fast from being heated up?

I think there is one of those breather plugs on the case somewhere like there is on the rear axle housing.
But I don't know where the plug is if there is one and how to best access it.

Could it possibly be plugged and causing that hissing noise heard with excessive pressure not being able to vent while heated up?

Has anybody else heard a hissing sound while unscrewing the fill plug?

 

Transmission, transfer case breather?
Discussion in '1st Gen. Tacomas (1995-2004)' started by Kristi with a K, Mar 11, 2022.

 

Awesome link Honda. Thanks

black97……
I see a can of brake cleaner in your future!
If there is a positive here, your transfer case seals are perfect!

Just spit balling here……
Put compressed air (not 200lbs or anything) thru the drain plug at same time douse that breather to clean
??
GL

 

Plenty of brakleen on hand
I have to find out where that plug is located and reachable hopefully
Are there better pics of its location out there other than a parts diagram

Cracking the check plug sounded similar to opening a fizzy root beer lol

I don't even know what the level should be at when it is exceptionally hot

 

That’s crazy about the fizzy sound

from those posted pix on other thread,

Possible access to view through shifter hole in floor tunnel (?)
Possible to grab that breather hose with a tool, and get access to the clogged breather vent (?)

 

found some decent pics in here...

Swapping the Transfer Case – ADVENTURETACO

no clue where the breather vent plug is at lol, cannot see it on there! my eyes are glazed over

 

I’m not a first gen guy, but I suspect it’s under that red plug

 

Should be right here

 

thankYou!
is that vent plug replaceable without having to dismantle the transfer case off of the truck?
should it just be able to wiggle like the one on the rear axle or is it a different type of vent plug
i might be able to reach a hand of there to feel around & see if it is seized

 

blew up and cropped that area for a closer up
well there it looks like it is located to the right of the blue marking

 

Yea that's the one. It is replaceable, so long as you can physically get to it. Might be in a hard to reach location. If you can't get at it from below, I'd remove your shifter boot and try to get it from inside the cab above it.

 

The R100 Tcase breather vent is pressed into the top-rear of the manual gearbox rear case. The R150F tranny breather vent is pressed into the tranny shifter tower itself. A hose from that red plug next to the Tcase J-shifter tower in your pic leads to the rear tranny case. Toyota put the vents up at a high point and you can service both factory breathers when you pull the shifter boot. Small hands are useful to do it but mine are XXLarge.

OEM breather vents on R150F tranny:




Both the tranny and Tcase breather vents were extended on my Taco, but you can see the armored vent hose on the upper right attaching the Tcase to the tranny case:

 

? that other pic is a different variation of Tcase for a different year of gen1 Tacoma?
i probably have the '97 one like you do except the R150F is no longer a '97 model on mine currently and it is having some issues yet to find out about