Rare piece in Mazda 6

Hello everyone, today a client has come with a Mazda 6 of 2004, 1.9tdi diesel <- does not carry a citroen engine.
And he tells me when circle paste petardazos, I lame the car I accelerate it in Relay and I see that he starts throwing a lot of smoke through the engine, I turn it off and hear it as a gas bottle throwing smoke for a while. I look below and see an iron tube that comes out of a metal box on the right side attached to the firewood firewalls.

What is that box and why does a metallic surplus that pull smoke? I also seen that it throws a very clear clean oil.

In that box a water tube enters and another water leaves the heating.

All levels stam well, there are no codes of breakdowns.

And I thought that box can be something of the boxing but that it throws smoke and clean oil, I don't know, something weird.

Hello IGRY, if you can put a photo, it could help you better, a metal box with a metallic tube can be an expansion valve of the AA, and the oil, being clean Nuy, it may be the one that is mixed with the compressor gas, it is a bit of it if the air conditioning is put dehydriator ... Specify it, if not, it's hard to tell you, greetings

Nothing, a topic resolved a colleague from the Mazda house, I told me that it is a webasto heater, which in nordic countries is used for a few seconds to heat the water.

The issue by which it worked all the time and a lot of smoke is because the engine temperature sensor looks bad and does not indicate well or something.

SOLUTION Remove the feeding plug and stop bothering, there are no codes of breakdowns and the car works perfect.

Thank you very much for the information, it is very good to know about these "rare pieces" that are used very little but give problems