rear axle vent question

[Pops]

Hello fellow truckers. I am new to this forum and happy to have found it. I own a 66 GMC. It's an inline 250 with a 3 speed. It's been modified mechanically but it looks, sounds and drives as an original (I think; lol).
I've always loved trucks but this is my first classic. I am still attempting to learn what is wrong with it vs. what is the-nature-of-beast. Especially when it comes to various sounds.
Since there are many days, hours, and topics to cover, I will attempt to write on one issue/topic at a time.
My first question concerns the axle air vent. Looking back from the cab, its on the right axle tube; its about 3/4 inch tall and it's shaped like a mushroom (dimpled on the sides of the so-called cap).
QUESTION: Being a conservative, I'd like to know how to verify that the vent is doing its job without breaking it. It looks to be clogged with black paint as one of the PO painted the entire undercarriage. What concerns me is that it looks so simple to remove, and clean, that I can't help but believe something will go wrong if I just reach up there and break it loose. What risks are involved if I remove; does it take heat; PB blast; etc.? If I break it am I going to lose fluid, etc. If I don't remove, could I just put some heat to it and use a pin to pick the gunk out of the mushroom/cap.
I'm a family man who loves God and Country. Pops

[FetchMeAPepsi]

Hi Pops! I cant help with the axle vent thingy. I never knew they had vents but I will say you sound like my kinda people! Welcome to the club!
And you are doing it right too. You do need to make a new topic for each problem. That way idiots like me can search the forum from time to time to figure out fixes when we get to that point. Thanks!

Someone will come along in a minute and help with the problem. We have a bunch of helpful guys here.

[Pops]

I look forward to the help. I stumbled on the air vent feature as I was looking up info on my dana 44; 354 rear end. I first saw it under an article by folks that sell truck parts through Jim Carter. Its a breather that should be clear from what I read. Like all breathers, if they work, there's less pressure and fewer leaks. And, I have a slight leak at the pinion seal so I thought I'd start with the vent. LOTS cheaper.

[BarryGMC]

Its just pressed in. Its pretty hard to plug however. At least completely. It really does not have much air movement through it. As the rear warms up and cools down it let's the pressure stay balanced with The out side.

[BarryGMC]

Ditto to your last line. PS I would not worry to much about it. Barry

[Pops]

The air vent cap spun freely. Thanks for responses and welcomes. Pops