For several years I have taken off the "air box" to make repairs.
It is split into at least two pieces actually.
If you look at the part of the air box (which hold the air filter) at the bottom
by the transmission, it joins the other part of the air box (which screws
onto the front top of your car). It is joined with a cheap gasket which
I am sure leaks air.
At the joining of both parts, the shape is rectangular, not circular, making it
difficult to repair.
Nissan sold me the cheap little foam gasket for $15...I took it back-no
way it would hold.
I used a rubber seal part from Lowe's hardware to reseal this area. It is part
#70389, 3" PVC IPS Donut (used to join pvc pipe). It has a large lip to cover
both rectangular parts of the air box where they join.
I put the gasket on the air box which joins the front of the car.
It was kind of tough to get it on and I also used some electric tape for a permant hold.
I fit it over the other side but will use a hose clamp as additional insurance agianst
air leaks. It fits pretty snuggly as well. When removing the air box, i will remove
the permanant side first after removing the hose clamp
