2005V70 2.5T What is the small hose on thermostat housing?

[Zeeko]

Hi All-

I guess I didn't look very closely at my thermostat housing on my 2004 V70 2.5T, but I purchased a new one/upper rad hose recently. When I popped the hood today to go to replace it, I noticed there's an additional small rubber tube coming off the brass nipple of the thermostat housing- does anyone know what the part number for this is? I can't seem to find the hose on any diagram- even in Vida.

Here's the thermostat assembly- you can see the brass nipple where the small hose connects:

https://www.ipdusa.com/products/7007/11 ... -o-gasket

Thanks!

[cn90]

That small hose goes from the PCV pipe coolant system ---> tstat nipple.
That small hose is part of that convoluted PCV-Coolant pipe, PN 30650578 (about $180 or so).

If you are concerned about that small hose, then use a generic heater hose at local auto parts store.
Get the Gates brand hose.

On the other hand, you can re-use it, that hose rarely goes bad before 200K miles.
When I did my tstat in the 2005 XC90 2.5T, I re-used that small hose, you can see it in the DIY I wrote below:

DIY: 2005 Volvo XC90 Thermostat + ECT without removing PS Pump:
viewtopic.php?t=79031

[abscate]

Be really careful working around that end of the PCV, the vacuum connection is plastic and will snap easily, especially if the part is 13 years old