Rear diff under pressure?

so I was installing an ARB diff breather today.... and as I took the factory breather off.... I noticed it was under pressure, and was venting a non-insignificant amount of air as I unscrewed the breather.....

I’m not terribly concerned... but is this normal? The car hadn’t been driven for at least 24 hrs, so the diff was cold.

But shouldn’t the factory breather have vented that pressure?..... it seems like keeping it under constant pressure would eventually wreak havoc on the seals.

 

AKA "significant"

Can't answer your question, but by chance was the existing breather plugged?

 

The sound you heard is completely normal. The factory "breather" is actually a one-way check valve- that's why it's a good thing you upgraded.

 

It's a one way check valve, it doesn't suck in water it only lets out air. This breather mod - at least for late model Tacos - is of limited value

 

Well I did the ARB breather relocation (at 3500 miles) and when I took the factory breather off a lot off air came out as in highly pressurized.

 

No wonder it wants to leak through some diff seals. Why would the thing be highly pressurized ?
Check valve not working ?
Need to check mine now.

 

Isn’t the reason for the mod to not suck in water through the axle seals when the check valve “breather” slams shut? Obviously it would only be necessary under certain conditions. Such as when the diff is very hot.

 

Exactly, that’s what I’ve been saying for six months in these other threads where members are having the leaking diffs.

However, there’s members that have done the aftermarket relocation and it still leaks. But, I wonder if they’re just reusing the stock breather and relocating it.

The ARB is a two way breather, completely open on both ends, so it always vents.

 

Nice, you should do a write up on the ARB dif breather, I just bought it a couple days ago

My understanding is that when entering cold water, water can get sucked in through the axle tube seals. The dif breather allows the axle to equalize and thus prevent water from being sucked in.

 

There’s a couple write ups already. It’s a 5-10 minute mod, very easy. I ran it into the right side storage in the bed. There’s already drain holes in the compartment you can run the line through.

 

Mine did the same thing when I installed the breather. Yes, it isn't supposed to breathe in.
As for the vacuum, can't fully answer but I suppose the axle seals will allow some air back in after the diff cools

 

Interesting, I was planning on running it up to the engine bay. Also read that the tubes of an odd diameter or something and dont connect well.

 

I guess the ARB provided air lines are metric or something and dont easily mate with other air lines.

 

The engine bay is a long ways, I’d leave it near the back of the truck. Others have put it behind one of the rear tail lights (you have to take one of the tail light covers off).

 

Did you just do the dif or the trans and transfer case too?

 

Those, and the front diff (also your crank case) already are vented

 

Just the rear diff. I’m looking into the manual trans and Tcase which others have done. The front diff is already up high in the engine bay from the factory.

 

Yeah the front diff, transmission and transfer case breathers are all mounted up pretty high.....but seeing as the rear diff is holding pressure, I’m wondering if it’s not worth it to get another arb kit to mount upfront to get rid of the factory breathers

Also I think someone asked, the arb kit is 8mm macro-line

 

That’s been my thought as well. Actually the trans and Tcase breathers are not that high up, they’re just under the bottom of the cab.

 

I wonder why they ran a breather up front but not in the rear?