Air filter intake pipe

There are 2 corrugated pipes coming from the fan housing in the picture below. The third pipe is connected to underneath the air filter and disappears under the tinware. It's presumably to preheat air during colder weather?? Does anyone know where this third pipe goes to under the tinware??

Thanks in advance

 

It's goes to a metal air scoop. I brought 1a few year back from vw heritage I think. Basically it just takes warm air from between the head the engine block.

 

There should be a pipe like this
http://www.justkampers.com/113-119-519-g-warm-air-pipe-vw-t2-1600cc-1967-1979-beetle-1968-on.html

Although I've got one and can't get it to fit!

 

Brilliant! I had a recon engine fitted a few months ago, but this pipe was omitted so Ijust blanked off the flange to the air filter. As the weather has got colder, an enormous flat spot has developed when accelerating. This missing "hot air scoop" may well solve it!

 

It'll certainly help.

 

Interesting, not seen that before. ( Gotta T4 )

 

Also known as 'The Hoover bit" after Bob Hoover, the aircooled guru who used to bang on about it's importance

 

Nooooo! Hoover bit's on the oil cooler.

 

is it?....I always thought it was the hot air scoop as mentioned...I sit corrected

 

The scoop or 'stove pipe' has long lugs on it that may need bending a bit before they line up with the tinware screws. And it does catch on the tinware where it pokes through.

Certainly an excellent idea in cold weather, when I changed to a progressive I took all the stock stuff out but put it back when I discovered how much better it was with the stock air cleaner and preheat.

If you read the Ratwell website he points out you can get away with threading the aluminium hose through the tinware and pointing it near the fins on the No.2 cylinder head - you might need to make a strap or something metal to hold it lined up.

 

What does this mean?

 

I can't get mine anywhere near fitted, bending lugs or not, so was going to try the extended aluminium hose thing. Way down my list of jobs though!

 

I just taped it over so all the air went through the part normally exposed to just the engine compartment air. Rather pointless really.

Today I refitted the corrugated pipe and the scoop, which the "mechanic" had just thrown in a box. Took a couple of hours of fiddling but would have taken minutes with the engine removed.

There's a flap at the end which directs air from either the engine compartment or the hot air scoop. Seems to be attached to a vacuum tube, but I don't know if it works or what it does. I just jammed it to force hot air through over the winter

I'm looking forward to going out on a decent run to see the improvement.

 

It probably won't want hot air once it's warmed up. Why not test / sort the vacuum system?

 

Strangely, there was no hesitation until it was warmed up. Sucking the tube leading to the mechanism didn't seem to do anything.

I've also checked and adjusted the accelerator pump to give the correct amount.

 

Took the Bay for a run this afternoon with the air intake now drawing in pre-heated air from the "scoop". Drives like a dream with no flat spot on acceleration

Immediately on stopping, the corrugated hose from the scoop is warm to the touch rather than hot, and clearly the combustion system is happy and so am I

Some useful info at http://www.vw-resource.com/air_cleaner.html#intake

 

As Zed said, you do need to make sure that the thermo flap is working. The engine doesn't like breathing hot air once fully warmed up.

 

What you had was Carb. Iceing.
What you've got now is carb. heat.
Tony