Rear diff seemed pressurized - clogged breather?

I did my 30,000 maintenance yesterday. I noticed that when I unscrewed the fill plug that air escaped from the diff. Not a ton, but it was enough to be noticeable. Do you think my diff breather is clogged? I'm assuming if it wasn't the air would have vented out the breather.

Is there a way to check and see if the breather is working correctly? It looked OK to me, the little cover rattled around, it wasn't caked in mud/dirt or anything. I've babied this truck and don't see how it could be clogged unless it came that way from the factory.

Any ideas, or is slight air escapement out of the fill plug normal?

 

A small amount of pressure is normal. The breather is actually a one way check valve, Lets hot air out, does not let air and water back in. The amount of pressure not being eough to open the spring loaded check valve is what you are seeing when removing the plug.

 

My experience with an old Toyota truck that had the same breather setup:

I would check the diff fluid level and there would be pressure. I was 16 and did not know any better, ignored it. The next symptom was gear oil leaking all over my brakes from a failed seal. Replaced the seals, brakes (learning experience), cleaned the breather. When I was done with all that I would check the gear oil at each oil change and there was never any pressure buildup.

Havn't been doing the maintenance on my 06 myself, so can't comment on the 2nd gen specifically.

I would say get a can of brake cleaner, remove the breather and flush it out till you can blow air through it.

 

Thanks!

I slightly rounded the fill plug trying to break it free, so I've got another on order. I'll drive the truck a bit and replace the fill plug and see if I get the air venting out again.

 

Do you take your truck off road? do you do water xing? If so you might want to consider a remote diff breather.

 

Just unscrew the brather from the diff. and see if you can blow through it. The spring is light and with just a small amount of 'puff' you can blow through it.

Click on the link in my signature below to see the breather mod which will protect the rear diff. from getting contaminated if you go into water over 18" deep... The same way Toyota protects the front differential.

 

I've had my rear seals replaced 3 times over the past couple years. They tell me the vent keeps plugging. Why is this ? Any suggestions? No off road. 1998 I haven't done anything to bend/damage axel. Is there something I can do to keep vent from plugging and blowing the passenger tire. ??

 

This (it will eliminate that breather 'vent' altogether) :
https://www.tacomaworld.com/threads/diy-differential-breather-extension.15223/