911 3.2 airbox port? What is this?

M491Cabriolet · 01-21-2008, 10:34 AM

I just noticed a round hole (factory made) about 1/2 inch, with like a grommet or ferrule in it, through which there can be seen about 1/2 inch of daylight in the bottom of the fixed half of the airbox of my 3.2 Carrera. This looks like some sort of a breather port to me, but it seems strange because it is between the filter and the intake. If you can imagine the bottom surface of the fixed half of the air box, it's about 1/4 of the way from the forward edge of the box. I have a spare air box, which also has this port. I have no idea what this is for, but it seems to me that one would not want unfiltered air going into the engine. What is this thing? Should there be a breather tube attached here? Thanks.

tonythetarga · 01-21-2008, 10:41 AM

I think that is where the oil tank breather line goes. Have a look and see if it is lying on the back of the engine or engine compartment. You should be able to trace it from the tank.

M491Cabriolet · 01-21-2008, 10:53 AM

Thanks. No, that one attached to the vertical side of the box. This hole I'm talking about is like a drain hole in the horizontal side of the box (the bottom). There is no way to attach a hose to it. Any idea of what this is?

Mitch Leland · Mitch Leland's Garage

I have just installed my 3.2 engine and found that someone had not attached the rubber hose bracket at the back of the air filter housing, it turned out to be a real challenge to get the 2 no. 5mm bolts into the bracket and housing.

I also noted the the oil tank vent line was kinked up against the firewall structure, I cut off the plastic nipple, drilled a larger hole, machine an 90 degree AN fitting with large aluminum washers and AN nuts so the hose went vertically off the air box.

As for your extra hole I would use a metal plug as well as some silicone to seal it in...

M491Cabriolet · 01-21-2008, 02:57 PM

If it were not a factory port, I would agree that it should be sealed, but this is a factory port. There's the exact same thing on my extra air box. I wish I knew what it is for and what, if anything, should be attached to it. Doesn't anyone know? Thanks.

dshepp806 · dshepp806's Garage

Gotta' pic?

Not the bottom mounting hole (for the stud)???

Mitch Leland · Mitch Leland's Garage

I'll bet Doyle is right... If the hole is for a 6MM bolt size then you're missing the rubber isolator that has a 6MM stud out both ends, one mounts to the air plentum, then other goes through your mystery hole. If the hole is in the forward part of the air filter box and against the inside back wall then it's the mounting hole for the shock mount. By the way I believe this hole has an aluminum reinforcement around the hole.

I have a 45,000 mile car, but it's incredible what P.O's or their mechanics have left off the car. It doesn't take long to cobble up small parts here and there.

M491Cabriolet · 01-21-2008, 06:30 PM

Mitch, That could be it. There are the four bolts that hold the box to the air sensor, the stud through the front part of the box (through a sort of tab), but no support toward the back of the bottom of the box. There is an aluminum reinforcement (that's what I was referring to with the incorrect "ferrule"). So, there should be a stud going through the mystery hole? I wonder where that is. I'll have to have a better look when it warms up a bit. For now, the car is tightly tucked under its cover in the garage. The tires are no good for temps under about 40 degrees farenheit, so we wait for a warm up... Thanks!

4flyboy · 4flyboy's Garage

Nice catch Mitch!

dshepp806 · dshepp806's Garage

mmmm...good luck!