hey guys i meant to ask if pressure buildup is normal in the rear diff. i changed the oil out a month or so ago and forgot to ask. when i loosened the fill plug it hissed.. never had one do that to me.. granted i have only had jeeps in the past.. first yota

 

check your diff breather. it may be clogged.

 

so i am assuming its not supposed to have built of up pressure?? also where is that breather??

 

borrowed from wattora (thanks rob )



while your at it you might as well do the diff breather extension mod, http://www.wattora.com/index.php?page_id=12

 

If you let that pressure go too long, eventually you're going to have blown axle seals and a set of rear drums that refuse to let go even with the e-brake off and pedal released (ie you'll be in need of a rear brake job and have to change those too).

 

so how do i unclog this? oh and thanks. ill probably just clean it and put it back on. i dont see much mud at all.. thank mtc

 

how do you clean the factory diff breather? can you take it apart and clean it what??? i doubt ill do the mod.

 

The stock breather doesn't always bleed off pressure, so it is natural to have some in there. It works by bleeding off when the top is swiveled by hitting a bump or what not. Next time you drive your 4Runner just reach up to the breather and move it around, the pressure should then bleed off.

 

oh ok good deal. i may take it off to check and see if its clogged though

 

I check mine constantly, as I enjoy submerging my axles on a regular basis. The way I do it is to first remove and clean the breather, use solvent then rinse thoroughly and dry. Then I blow into the open end gently to see if it vents. I like to feel a "pop" as I blow just hard enough to open the valve. Next, suck the same end and see if it seals. It should be impossible to suck air in through the top, which by the way does not allow the valve to be opened. There's no swivel involved. If that were the case the valve would be forced open at the slightest force. It is not designed to do so, infact it's designed not to. This keeps water out while submerged in breif circumstances where needed, if it were to be bumped open in a stream crossing/deep mudhole that would be trouble. Toyota knows better.

 

hmm interesting! maybe you should to the diff breather mod

 

Yes I am interested in that one. I'm still at the top of a looooooong list of future goodies. You know I heard recently the average joe spends approximately 8-10 years on his project truck, before it gets to the just maintainence phase.

 

LOL i can beleive it

 

I had mine hiss at me too at one time...eventually like MTL said I did have to do a brake job and replace the rear seals cus' they got gummy from the axle grease/fluid. I like to submerge my axles too during water crossings and big puddles, the diff breather mod is only like $10 and it's well worth the piece of mind.

 

well i dont submerge lol!! couldnt i just get by with cleaning the factory breather??

 

From what i learned, if you're in mud, or water over your wheels/tires periodically---it's good to extend the breather. On 3rd gen's the front is already extended, it's the rear you have to mod. Should cold water or some slick mud get in the breather....cold water and hot diff oil don't mix----BYAH..blown axle seals or leaks IMHO.

 

gotcha thanks guys