Airbox lid

[940volvoman]

How crucial is it that the lid on the airbox is sealed?

Mine has not been an airtight fit for a few years now, but the car seems to run OK

Granted, it is help in place mainly by the MAF hose on top so is not floppy loose, but it is not fixed as Volvo intended.

Do I need to or can I just carry on?

[Jimsiss]

If you want purely filtered air and no crap then pretty crucial otherwise it doesn’t matter. Mine has no clips left so my dad screwed it shut 😆 (when he owned it before me).

[V40onepointeight]

Not sealing it properly sends some unfiltered air through the MAF, so at some point you might expect that to play up. Happily a quick spray of the right stuff cleans up the MAF nicely. My 940's airbox is also missing a couple of clips so whenever I change the air filter I then use duct tape around the lid to seal it.

[Rversteeg]

I would not be overly concerned about the airbox lid not being fully clamped. As long as it is properly located in position the vacuum created by the air being sucked in by the engine will pull it on quite tightly.

I am just guessing the airbox lid dimensions, but if it is something like 15 x 27 cm, a vacuum of just 0.1 bar would pull the lid in its slot with 40 kg force!

[Laird Scooby]

A couple of long, wide cable ties round it would hold it fairly tightly shut or you could buy an el-cheapo thin ratchet strap (or a pair of) to wrap round the box then thread the ends into the ratchet, tighten and job done :

https://www.toolstation.com/thorsen-...own-set/p68419

Even a bungee cord round it would work...........

[SwannyUK]

Mine was screwed shut by the previous owner. Seems to be okay for now. The plastic has become quite brittle, and the metal clips corroded. At some point I'll get my arse in gear and sort a replacement, I'm thinking printed in ABS or PETG.

[940volvoman]

Swanny UK, thats just showing off!!!

Seriously,though I guess at speed the air was rammed into the airbox by extending a tube to the front grill it could escape via the edges of the 'box?

[Laird Scooby]

Originally Posted by 940volvoman

Swanny UK, thats just showing off!!!

Seriously,though I guess at speed the air was rammed into the airbox by extending a tube to the front grill it could escape via the edges of the 'box?

I think it was David Vizard (the Mini Tuning Wizard - before he moved to Californ-i-a and became David Vi-zard) way back in the 60s or 70s that either calculated, tested or both that to get a bost of about 1psi from ram air induction from the grille, you'd have to be traveling at something like 170mph and the implication was the drag created by the air scoop for the ram air would create more drag than the power improvement would overcome.
Long time ago since i read one of his books where that's mentioned so might have the figures somewhat askew but close enough for the purposes of the conversation.

With that in mind, what Rob says below would still hold true :

Originally Posted by Rversteeg

I would not be overly concerned about the airbox lid not being fully clamped. As long as it is properly located in position the vacuum created by the air being sucked in by the engine will pull it on quite tightly.

I am just guessing the airbox lid dimensions, but if it is something like 15 x 27 cm, a vacuum of just 0.1 bar would pull the lid in its slot with 40 kg force!

Something in the back of my mind says the filters are 183 x 283mm (there are two sizes, one is bigger than the other and i can't remember the other size) so i would guess the force would be even bigger.

[SwannyUK]

Originally Posted by 940volvoman

Swanny UK, thats just showing off!!!

I just think that a lot of these parts could be simplified and released to fit the standard panel filter etc as printable STL files, especially if it no longer becomes economically viable for Volvo to keep producing them.

[griston64]

Just buy some clips like this



Drill the airbox and use small bolts and washers