lovetharunner

My 4Runner has had a slight vibration in the rear between 60-65mph.
So tonight I got underneath and found this:



Specs: 94' 4Runner 22re 180K 5 Speed Stock Suspension with 31s
I haven't taken it off the road in over 4 months.

I am new to the Toyota scene and would appreciate any input.

Joshua

apalmer1

check the oil level, then pull the whole third member out and either buy a new gasket for it or use differential form-a-gasket. the formagasket works great and is much cheaper so i would recomend that. hopefully your vibration is being caused by something else and not damage to the gears from oil starvation.

algranger

looks like you got a leaky diff seal

lftd_86_yota

make very sure that your breather is moving freely... also, if the leak continues, then there is just a gasket on the rear diff seal.. not to big of a job. check lube before continuing to drive!!!

abecedarian

or maybe leaking drain plug?
I say that 'cause it looks cleaner than the rest of the housing so has probably been seeing oil longer.

Tofer

pull the 3rd member, clean it up and throw new RTV on it... make sure the diff breather is clean and extend it while your under there.. pulling the 3rd is pretty easy in the rear. jack it up, throw it on jack stands. 4 bolts on each side and the brake lines allow you to slide the axle out (tire, rim brake drum and all) then pull the 3rd member....

lovetharunner

Thanks for the help guys! I need some further help:

What is a breather - and how do I check it?

How do I check the oil - and what kind of oil do I put in?

Tofer

the breather is the knob looking thing on top. it allows air to release when the 90w diff oil gets warm and pressure builds. I would just drain the oil (bolt on the bottom of the housing) and re-seal the 3rd member then fill it back up with 90w diff oil. where are you located, someone may be in your area that can help.

drew303

is there a ton play in the driveline? Put the parking break on, put the tranny in neutral... then in gear (releases any tention the driveline) and get under there and turn the driveline, should only move at the most about roughly half an inch... less is better... If there is excessive play in the driveline you could have some other issues with the differential and ring and pinion.

Excessive backlash can be a big factor in highway vibrations.

In other news, you obviously have a 3rd member leak, probably from the 3rd to housing seal.

You don't need to go out and buy a gasket, just drain the oil, discconect the driveline, get ready to 'eff up your back, unbolt the 3rd and pull it out. Well you gotta pull the axles first. Inspect everything, clean it all up and use RTV silicone on the housing and third member mating surfaces, put it back on. Let it cure for 3-4 hours before putting oil back in. and if you wanna be safe, wait a day before driving it (but you dont really have to).

Before you pull anything apart, check the fluid and at least replace it. So pull the drain plug and see if any metal shavings are caught on it (its magnetic) Should be a lil bit of shavings but nothing excessive. If its got a lot, I would pull the third.

ALSO pull the breather on top and clean it up, make sure it aint clogged and is working right. A clogged breather will cause oil to find ways out of the housing, usually past the outer wheel seals but could also get pushed out the third member seal there.

goodluck!

YotaJunky

I second that...

drew303

yeah, the breather is that stem ontop of the housing. You can see it in the picture you posted in the upper right. just unscrews out.

PISTOL1000

hey cool mine does that in front and in back on the side its goood

lovetharunner

Wow - thanks for the response guys! This forum rocks!

I live in Eugene, Oregon. Do you guys have a DIY for removing the 3rd, cleaning it all up, and resealing it all back up?

I am a total newb - I don't even know how to check the diff oil. You said I need 90W diff oil?

Thanks again.

drew303

The bolt on the back side of the housing (center) looking at the axle from the rear-end. You just take that bolt out, i think its what... 22mm? stick your pinky in there and feel for the oil.

Of course make sure the truck is on level ground first. If you take the plug out and some oil seeps out, your full =p ..

You're looking for a few things

level of the oil, if its low, obviously it should be if your leaking
Looking to see if water is in it (does it look like chocolate milk?)
is it black, is it somewhat clear? (thats what u want)

And smell, how does it smell. If you pull that plug off and want to puke, you got bad bad oil LoL ..and it can smell reallly bad.

The front diff I pulled off my donor frame that I salvaged from the side of a barn =p ... that oil smelt rancid. hehe

Yea 90w gear oil is what you'll want to put back in. I think theres also like what is it 85-90, thats fine to. I think thats what I use in mine, i forget small details like that. The Haynes manual has those details listed in the front as well (good reference for torque and oil specs, otherwise nearly useless manuals LoL)

after draining, you fill it back up to the fill plug level.. obviously you cant put more in the axle as it'll just flood out the fill hole (obvious reason they put it on the side and not the top)

lovetharunner

Update!

Fluids were not terribly low (measured 2.5 Qts.) and was dark & dirty (but not smelly). Very small metal shavings on drain plug (sand sized). Cleaned caked dirt from exterior of breather and slightly loosened metal cap on top. Replaced fluid, tightened gasket bolts, cleaned axle.

Went for a test drive and experienced the exact same vibration from rear as before. Swapped passenger rear tire with passenger front. Vibration completely removed from rear, but now the steering wheel vibrated!
Took the tires to Les Schwab to be re-balanced and vibrations were eliminated. Les Schwab determined that one of the tire belts may be coming apart

Thanks for everyone's input!

Joshua