I attached an image with one part that I do not know what is it. I know that big fat hose is coming from bottom passenger side of radiator and I had some chocolate milk color liquid in it. When I removed thermostat and try to blow this hose, air was going nowhere. Is that normal or it is clogged somewhere? Reason why I didn't took it out is because I do not know what it is to order a new gasket when I put it back.

 

what engine is this? That big fat hose that comes from the radiator goes to the water pump and thermostat.

 

I thought I add my car to the signature. I have 2008 A4 Quattro 3.2L
That's what I was thinking, that hose should go to water pump and thermostat but when pump was out, I could not flush that hose. It bothers me because when I removed radiator, pink coolant came out from driver side hose while milky color came from this fat hose on passenger side of radiator. After removing the radiator, I flush it and there were no internal blockages. So I guess I need to take that out and see why doesn't flow. BTW...I do all this because I got low compression on cylinders 1 and 2. Well... when blow air on cylinder 2, comes out trough cylinder 1. I am trying to find the reason for blown gasket or warped head, whatever will be. I did not removed head yet.