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Modify air intake of my 406 to be less vulnerable to floods

Posted: Mon Oct 04, 2021 1:02 am
by joydivision
After finding the warnings on this forum (and other places on the internet) about the air intake of the 406 being dangerously low (or creating some strange water sucking situation, whatever it is), making it a high risk to drive through any standing water, I'm really decided to change the air intake of mine (2.1TD) so that it won't be so vulnerable. We have "moderate" flood situations here from time to time... What I'm thinking is a mixture from what I've researched on this forum and other places (munkymanmatt seems to have thought this through quite well, it's just a pity he hasn't reported back on this, now it's years ago: viewtopic.php?f=1&t=18835&start=60) and also from what I've seen on some cars, especially Japanese ones, including my wife's.

What I'm thinking is:

- disconnect the original intake "snorkel" (that goes dangerously low) from air filter box

- buy a new, flexible air tube and connect it to air filter box

- route this new tube to the left, leaving it's end close to the grille, to the left side of the radiator, close to upper corner, so that it can get fresh air coming from the front through the grille (there's a little opening on that side, munkymanmatt spotted this very well, all credit goes to him for this) and this is high enough to be protected from standing water and shallow waves

- I'm thinking of leaving the end of the tube not directly touching the grille and not directed straight to front, though, so that it would have additional protection against water coming in, for example from heavy rain. I think it could be pointed sideways or downwards (what would be best?). I take this idea precisely from my wife's Toyota, where the air intake is a tube that's left open ended close to radiator grille on the right engine side, inside the engine compartment, and is turned sideways by 90 degrees. This can only be for protective purposes, they could have pointed it straight towards the grille, there's enough room.

I am aware of the fact the the air at this higher position (very close to radiator) will be much warmer than from the original intake piping of the 406. But I also know that this is not a naturally aspirated engine, where it would matter a lot to have the coldest air possible. I understand that here the air travels to the turbo, where it gets really hot due to compression, then goes through the intercooler to be cooled down and only then into the engine, so the little difference between ambient temperature and engine compartment temperature mixed with some fresh air from the front, isn't going to make any difference, I think, right?
This way of thinking appears to be confirmed by the way the japanese engineers solved this in my wife's Toyota (which makes it much less vulnerable to water), it also has an intercooler, btw, and the intake is also quite close to the radiator.

Still, it would be great to have some feedback or food for thought of you people on here! 8)

Re: Modify air intake of my 406 to be less vulnerable to floods

Posted: Mon Oct 04, 2021 8:51 am
by D9406
Or you could drill 10mm holes in the bottom of the air box so that any water sucked, minimised because of the air box holes, up drains straight away.
Andy

Re: Modify air intake of my 406 to be less vulnerable to floods

Posted: Mon Oct 04, 2021 9:58 am
by GingerMagic
I'm not too familiar with the air intake pipework on your XUD engine, however this water ingress issue is definitely more problematic on the Hdi as the lower portion of the intake ( in fact at the lowest point ) are holes to allow for drainage I guess - but when submerged these holes let in the water....

I used to simply lift the air box off it's mounting bracket and rest it to one side, so there was a clear airway...

Re: Modify air intake of my 406 to be less vulnerable to floods

Posted: Mon Oct 04, 2021 10:42 am
by steve_earwig
I don't think the warmer air will make a noticable fdifference, especially in the winter...

On my HDi I took the pipe off from the bottom of the air box to the inside of the iner wing.

It's a shame the Volvo S80 air intake pics are gone, I don't remember seeing them either. Looking at them on ebay they look like they go the wrong way to me.

Re: Modify air intake of my 406 to be less vulnerable to floods

Posted: Mon Oct 04, 2021 4:43 pm
by trem1
this is how i lost my 406 :evil: :evil:

Re: Modify air intake of my 406 to be less vulnerable to floods

Posted: Tue Oct 05, 2021 11:34 pm
by joydivision
Thanks, some useful points here.
I don't know, it might even not be as bad as in the HDI, but for sure it does go right there down into the inner wing, which is kind of scary... so I definitely want to improve this, precisely because I don't want to risk losing mine, as this appears to have happened to quite a few people :cry:
I had read about the possibility of simply disconnecting the pipe and it will probably work just fine, even with the warmer air, precisely because of the engine being of the forced induction type. But then again, if I have the chance of doing it even better, fitting a new pipe to a higher located fresh air source, then go for it, right? That's what I though when I noticed the idea of munkymanmatt in that thread. I had a quick look the other day and it checks out, there's a little opening in the grille. I'm now pretty confident of going for this solution. I will get a flexible air tube.

Then the only thing left to decide is: if to point the tube's opening straight towards the opening in the grille (although not reaching directly the grille, this way the probability of strong rain coming in is reduced), improving cold air reception, or if I shall let it go there but point sideways, making the air go around that corner, almost totally avoiding any water that could theoretically come in while driving, but allowing the air to warm up more. For what I can understand, this slightly warmer air won't make any difference in the case of this type of engine, so I guess this should be the best way?