General Whats that tube for then ?

[silky666]

Usual technicaly ignorant question from me.
I recently replaced the fuel line on the Panda -and had to unclip/move to one side the front of the airfilter box.
I noticed that there was a small flexible metal pipe running from the bottom of this 'air intake' down to a small metal cowling on top of the exaust manifold. (see area highlighted in red)

Although it does enter the air box - it does not enter the manifold - but instead seems to just sit above and 'draw in' hot air to the airbox.

My question is:
What is it there for ? / What does it do ?

The reason I ask is that it was persished and hanging off - so I replaced it.
But all my knowledge of motorbike engines informs me that it is best to draw in cold air to the airbox -- not hot ?????
Confused.

Thanks in advance.
Silky

 

[custard]

its for cold starting,allows the engine to draw hot air in tro warm up.then the internal stat closes and it draws cold air in

 

[silky666]

so the fact that I replaced the rotten / holed / hanging off old one -with a spanking new sealed one - may explain why my Panda now seems to start like a dream for the first time in a year or so
Thanks for clarifying that.

 

[Chas Uno]

It's also of importance in cold weather for carb fed engines as it helps to stop carburetor icing from occuring!

It is also controlled by a thermostatic flap. If you look inside the front part of the airbox you'll see a flap connected to a plunger device. When the engine is cold it will close off the cold air intake (the black plastic pipe that comes out of the bottom left of the airfiler housing) and only allow hot air from the manifold to be drawn in. This helps the engine warm up quicker as well as stopping carburetors icing up.

Once the engine is warmed up the flap will start to close the hot air intake and open the cold air inlet. The plunger effectively keeps the air entering the air filter at a constant temperature, not too hot that it causes fuel vaporisation and not too cold that the carb will ice up.

In the summer it's not really needed, but in the winter if you have a carb engine it most definitely is!

 

[Alan.D]

I agree completely with that, without it my Sisley stopped several times on the M74 as the carb iced up then due to the engine temp a few min later it was fine till I got up speed again then it stopped again etc etc.

 

[petebarchetta]

just for the record, and to serve as a guide.
The diameter of that flange that bolts onto the exhaust manifold is 37mm:yeahthat: ,
Halfords sell a 40mm corregated heatsheilded tube that will fit this application.
every panda i've owned has not had this present when i got them, and the owners always recon it didnt start well in cold weather.
could'nt think why

 

[silky666]

well thats exactly where I got my replacement tube from.
Only needed a short bit - but they only sell a 1m length - so if anyone has a rotting one then let me know and I will post a precut length of tube to you
hows that for service

oh! i also have about a metre of fuel line spare too

 

[default_user]

I'll need one! The Panda I used to rebuild the 'Rat with didn't have one either.