What is this thing?

[jay79cj7]

I was under my CJ today ('79 258) and noticed a couple droplets of antifreeze hanging, so I tried to trace where they came from. I found this thing that I have never noticed before and have no idea what it is. About half way down the block on the manifold side there is this fitting screwed into the block. Looks like a brass hex with a plastic part in the middle. The plastic part comes straight out of the fitting, and then has two legs that bend up at a right angle. These legs are probably about 1/8" in diameter, and look like there is supposed to be a hose of some sort slipped over them, but there isn't. Where this thing threads into the block is where I think the leak is coming from. What is this thing? What does it do?

 

[berettajeep]

I believe it is emissions related. both of my '79 258 motors have them.
you should also have another one of these towards the front of the motor,on the manifold side,with 3 vaccum ports. again this is also for emissions.
my cj never had vaccum lines hooked up to them.
so i am not sure how important they are...

 

[derff96963]

Exhaust for a yj??

On my 76 engine is has what you are discribing and it is for the EGR valve. It is a vaccum Switch. The EGR valve is not ment to open when the engine is cold but after is warms up it opens. That switch is screwed into the Block into the Water jacket.

 

[jay79cj7]

so, what lines should be hooked up to this vacuum switch?