Leaking Rear Differential

2013 Toyota Tundra Platinum with 135,000miles.

Recently, I noticed a humming/howling noise starting at about 40mph and continuing to 50mph. Then the humming noise decreases or stops at 50+mph. There is NO noticeable vibration, or drivability issues, just a humming/howling noise.

I got under the vehicle and it looks like oil is leaking from the differential where it meets the driveshaft. I also noticed oil leaking from the vent hole at the top.

Maybe heat from a bad bearing causing it to leak from the vent hole?

Anyone have a similar issue? Any idea what this may be?

Thanks in advance! Curt

 

Have you checked the breather cap to make sure it isn't stuck? If it is, it may cause leakage as pressure builds up.

 

This is what I was thinking as well.

 

I gave it a tap when I was under there and it feels loose and springy. It appears to be working properly. I there any way to confirm its functioning properly?

 

I'd take it off and blow in it lol. It's a cheap part, can just replace it to be sure. Might just be the seal at the shaft spraying back as you drive too.

 

I took it off and checked it. It is working properly. I'm thinking a bad bearing due to the noise.

 

Did you push vertically right at the pinion flange? Did you check backlash as well? Backlash
can be ok just by rattling it back and forth but there better not be any vertical knock, rattle or movement
at all.

 

Just checked it, everything feel tight. No movement vertically or horizontally at the differential driveshaft junction. Guess the next step is to take a look at the diff fluid. I'll drain a few ounces and see what it looks like.

 

Drain it all. Need to look at the magnet on the plug.
Doesn’t mean the bearing is not shot it’s just not really bad. Could be the pinion seal
only is shot which isn’t too bad. Next step is put rear axle on stands and remove
driveshaft. Then remove wheels. Turn the pinion by hand. Now there is no load,
if the bearing is really bad you might feel it as it turns. I just pulled rear diff of my
Land Cruiser apart. I could almost feel it grate. It was shot but still went around.
The race was ground up by inner bearings. One step at a time.

 

Do you have 2 piece driveshaft? Did you check steady bearing in the middle and all
the u-joints?

 

Not a lot of ways to get lube coming out of vent. Best guess is that it is partially blocked. Pressure builds and then blows out of the tight breather and pinion seal. Might be worth a look inside the wheel bearing( pull abs sensor to look), as it may be blowing out of the axle seals also.

 

I'll drain it all and take pics this week after work. I'll post some pics when I have a chance.