Inyo_man
Don't piss down my back and tell me it's raining.
So after a recent trip that took me through Beef Basin, Bobby's Hole and over Elephant Hill, I decided that I was fed up with the level of dust intrusion. I adjusted all doors and siliconed the seals when I took ownership, so the first suspect(s) were the flow through vents at the rear corners. A little Pajero research, indicated this was indeed a problem with the early production NM's(I have an '01), in addition to the lack of a cabin air filter added to later production.
Long story short, cut into the blower housing and installed a panel of furnace filter media, as a proof of concept, and also because $50 for a Cabin Filter from Australia, seems a wee steep. Decided to do the same thing to the rear flapper vents and to see why I was accumulating "sand painting" levels of particulate.
The housing:View attachment 339682
Simply cut a panel of filter media to fit, closed the flap, and taped it shut. The cabin filter from an NL will likely occupy this role, as soon as some more $$ occupies my wallet. I am in the process of sourcing this filter domestically, so stay posted for filtration efficiency info and pricing for what may become a group buy for anyone interested.
So on to the rear, which I presumed to be the real culprit, based upon dust accumulation on the interior grills near the Pass. A/C and subwoofer. Removed the left side first, and, though filthy, the flappers were intact and functional.
The same couldn't be said for the the right side. It wasn't fully inserted, and the lower portion of the frame had been bent, all allowing massive flow by when the interior was in a negative pressure, such as having the sunroof venting, windows open, etc. Two-stroke guys know that a reed cage that doesn't allow the petals to close is no bueno...same case here:View attachment 339686
As a recovering OCD that has recently taken "perfection is the enemy of good enough" to heart, and after contemplating some plastic welding, I decided simply to duct tape the malfunctioning reed cage. We seldom carry passengers, and the 3rd row has long since been removed, so why not. Additionally, as it adds more restriction to passive positive flow, I figured it would further help creating a positive cabin pressure.View attachment 339687
View from Exterior:View attachment 339696
Note that one side of the media has a smoother mesh "face".
I placed filter media both on the interior and exterior. The media I used was very fibrous, and even the smooth side, had individual fibers sticking up enough to prevent the flaps sitting fully closed. A quick trim and everything sealed well. Be certain the flaps lay flush, or you just added filter media for your "open all the time rear vents".
The exterior:View attachment 339688
In position:View attachment 339689
So how does it work? Awesome! Drove an extremely dusty road, located by a local gravel operation back and forth in several states of A/C On/Off, Recirc On/Off, Sunroof, Venting, etc. Windows open creates dust, barely, and even with the roof vented, and driving through my own dust cloud...NO DUST. I may ultimately replace the filter with some material from Unifilter or something similar, but for now, dust free and loving it!
Total time: 1.5 hours, including the road blast. WIN.
Well done!
Did the same thing to my rig years ago.
(Next time I'm visiting my brother's property in West. Oz. I'll bring back a couple of extra cabin air filters...)