Small vacuum tube

Anyone know what the small tube is for, which is connected to the top of the air cleaner hose directly behind the filter housing? Mine goes across the bulkhead and is open ended. Have searched in previous comments but can't see anything.

What engine ?
What car ?
What year ?

Oops 300tdi, 1997 Defender. I think a lot of vehicles have these but they don't say what they're for.

miktdish said:

What engine ?
What car ?
What year ?

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I thought you might have an idea. Maybe not.

Is it before or after the air filter ?

D1Nut said:

Is it before or after the air filter ?

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After. On the large turbo hose directly behind the filter housing.

On my friends 300 tdi defender we purposefully linked the front diff and trf box and g/box breathers to after the filter
Alas he no longer has the vehicle - and we used thin tubing, attached the whole lot together using the bulkhead as a securing point

That's about as much as I can add

lrmonks said:

I thought you might have an idea. Maybe not.

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It was a fair question to be fair
@miktdish ’s balls ain’t crystal ones. I hope not anyway

meego said:

It was a fair question to be fair
@miktdish ’s balls ain’t crystal ones. I hope not anyway

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No, I didn't say it wasn't a fair question. I did say Oops (I forgot) and sent the reply with the details of my vehicle afterall.

Haven't got that on my 300tdi and don't remember seeing it on my mates.
I can't think what it would be for either. The air is being sucked through the filter and the elephants trunk (by the turbo), I really can't see any advantage in having an open to atmosphere pipe ?

Can you post a picture ?

Thanks, I will pop out and take one in a few mins. Not much to see though as it's completely broken off, just a stub remaining.

miktdish said:

Haven't got that on my 300tdi and don't remember seeing it on my mates.
I can't think what it would be for either. The air is being sucked through the filter and the elephants trunk (by the turbo), I really can't see any advantage in having an open to atmosphere pipe ?

Can you post a picture ?

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Not a great image but with my crappy camera it's the best I can do. The black thing on the right is the air cleaner box.

Good picture, clearly see what you have.
I haven't seen anything like that before, at all.
I see you have all sorts of cables and pipes running across the back of the engine cable tied to the heater control cables...
I presume they are for boost gauges, EGT and additional windscreen water jets etc ?

Perhaps the PO had some form of vacuum gauge on the air inlet ?
Can't think how that would be usefull though.
Where does that black pipe go to ?

miktdish said:

Good picture, clearly see what you have.
I haven't seen anything like that before, at all.
I see you have all sorts of cables and pipes running across the back of the engine cable tied to the heater control cables...
I presume they are for boost gauges, EGT and additional windscreen water jets etc ?

Perhaps the PO had some form of vacuum gauge on the air inlet ?
Can't think how that would be usefull though.
Where does that black pipe go to ?

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Yes I have all sorts connected. It doesn't go anywhere, just tied to the cables as you noticed and it had a screw in the end. Just doing some work at present when I noticed the pipe so it is a bit untidy. I bought it in 2006. It only had 36k on it and it's still in great condition except from the usual rusty bits. But I think I'll just stick a self tapper in it to block it off as I haven't noticed any issues anywhere I just wondered about it. Thanks again.