Anatomy Of A D40 Air Filter

[Old.Tony]

Having had some not-quite-successful dealings with Nissan over my air filter, I removed it myself and attacked it with a cleaning cloth and some Sikaflex.

I took some "before" shots because afterwards it'd just look like a box, and I thought someone might find the insides interesting.

What's even more interesting is that there was a shitload of dirty water-staining inside, as you can see in the photos. I'm going to disassemble it again after I've done a few runs - particularly water crossings - and see how it looks (disassembly may be little more than dropping a camera inside to see it).

Anyway, it's fairly easy to see the air path from this picture:

Air enters the through the uppermost pipe via the guard intake (which is sitting the wrong way in the photo, sorry, can't fix that now!). It passes through to the baffle chamber, which is the large round section below the main box. It then comes out the right side and is fed into the bottom of the main chamber from the side.

I have to say that my air box was in pretty bad shape. Every joint was loose - the small pipe to the right of the main box shown above was completely loose. I sikaflexed all of the seams and joins, then installed it and sikaflexed that as well.

The baffle cover (shown on the left in the above picture) had broken free and was hanging by a couple of remaining clips. They glued it in with a brittle adhesive - give it a bit of heat and some vibration and watch it come apart - and my car's certainly seen enough of both!

Looking inside the baffle was curious. The chamber can be seen in this photo:

The baffles are filthy. It almost looks like a lot of water goes through there. There's a tiny (about 1mm) hole in the cover (and a similar hole in the base of the main chamber). I did NOT block these up, as I want the water to get out of the box!

The amount of dirt bothers me. It's something that I'll keep an eye on.

Anyway, I thought it was interesting. Now that it's all sealed up, my engine is quite considerably quieter. I haven't fully sealed the guard-snorkel interface yet - I'll get to that one day.

 

[Boxy]

u will get a noticable difference in horses if u **** all those bullshit u turns off and run your snorkel traight into the box aswell as decreasing the amount of joins that have t be water tight, probably i lil better in fuel economy aswell coz it aint trying to suck air through a straw

 

[lookskyward1]

Tony that is a worrying amount of muck in there, while you're sorting out the airbox it may be worth taking out the baffle, have look at this;

http://www.nissan-navara.net/viewtopic.php?f=9&t=10858&start=20

 

[Old.Tony]

I did remove the baffles and cleaned them thoroughly. The outer baffle is held on by two clips (one of which I cleverly broke but that wasn't important) the second one is held in place by the first.

They're spotless at the moment. Will see how they look after my next water crossing.

 

[joe2006]

Interesting to see what is actually inside.

After taking my car back to the dealer to properly seal the snorkel, they pulled the airbox apart and sealed up all the joins as well as removing the foam between the ducting and inner apron.

In my case there was a definite but unwelcome increase in induction noise from inside the cabin which I must have now gotten accustomed. Either that or my hearing has deteriorated.

Like you, they said they did not seal the two drain holes.

Evidently fitting of the snorkel does not normally involve sealing the air filter box. The principal of the dealership said to bring it back and they would fix it however when my wife dropped the car off, the bloke in the workshop questioned her as to whether I had ever owned a 4WD before, suggesting I was some sort of dickhead.

You will no doubt be a little more confident at your next water crossing.

Nice photos.

 

[ourd40]

Pulled mine out yesterday just to have a look at it and i was surprised that i could see through all of the joins on the pipes. I was going to seal everything but did not have anything to seal it with and could not seperate it like you have. How did you seperate pipes from the box? And what did you use to seal it? Thanx

 

[big zetor]

when i pulled mine apart i was shocked so many gaps and very restrictive air box and a stupid foam seal between air box and snorkel, Dealer told me it was a dust snorkel dont bother trying to seal the piece of s#$t airbox just go straight into the side of it from your snorkel and bypass all that other crap.

 

[Old.Tony]

Pulled mine out yesterday just to have a look at it and i was surprised that i could see through all of the joins on the pipes. I was going to seal everything but did not have anything to seal it with and could not seperate it like you have. How did you seperate pipes from the box? And what did you use to seal it? Thanx

There are clips that hold the pipes in place. In the top photograph the uppermost yellow line almost points directly at one on the air box itself. I used a flat-bladed screwdriver to depress them and/or lift the plastic so the clips disengaged.

The sort-of 'U'-shaped pipe (the third object from the left in the top photo) does NOT have anything retaining the lower part of the pipe - it uses that sponge to seal it (woefully, I might add - my sponge had collapsed into mush). This pipe only has a single clip in the top, the part that is inside the main part of the air box.

The cover on the left side is bloody well glued on and it's crap glue! If yours is on tight then you'll just have to work at it. The face around the rear (the service sticker on the airbox faces forward) is the flat face with the glue, the front face of the cover clips into place.

I used real Sikaflex to seal it. Took me half an hour to seal it up neatly, 5 mins to put the filter box back in, and 2 days to clean the shit off my hands.

 

[ourd40]

Thanx Old Tony,
I will have another go at it later in the week and hopefully not break anything.

 

[stiffy21]

I attempted to remove my baffle in the airbox today because I was told it was a kind if 'silencer' so I removed my airbox and realised the section that holds the baffle is non existent in my airbox. I have a 2010 2.5 Thai built st. do I have a baffle or is it just somewhere else?

 

[user 10312]

Thanks for the write up and pics Tony.

Have had mine out when new. As usual they didn't seal it when the snorkel was fitted before delivery. That U shaped pipe was making an anoying vibration to. All sealed and sorted now. Like yourself, did not seal those drain holes and left the pre cleaner hooked up.

Be interesting to see a Dyno test, one with the pre cleaner in place and the the other bypassed.
I would take a punt that there would be very little and more likely nothing in it.

 

[Old.Tony]

Stiffy, it's entirely possible that they changed the airboxes between Spanish and Thai builds too. Next time I get close to a Thai model I'll take a look.

Tappet - might be very interesting indeed. I'm willing to bet you're right - there will be a very marginal difference, but 1% is next to nothing and not noticeable in the greater scheme of things.

 

[stiffy21]

Stiffy, it's entirely possible that they changed the airboxes between Spanish and Thai builds too. Next time I get close to a Thai model I'll take a look.

I'm sure they did because the bloke I ordered an air filter off gave me one for a spanish built and it didnt fit, just a tad longer

 

[skullbone]

hi

I have a slight leak just after on the exit side of the air box around the large o ring. I have replaced the o ring but there is still a slight leak.

I was wondering if be advisable to use sikaflex on this area as well?

 

[Old.Tony]

As long as the surface is cleaned properly, sure. Sikaflex sticks to the plastic of the airbox very well. It's a vacuum area - Sikaflexing the outside of the gap is better than coating the inside.

 

[skullbone]

tar thanks