volvo-boost-pressure-valve-solenoid-valve?

jonahjays · Post by **jonahjays** » 25 Sep 2019, 11:19

Hi All, I am looking for the name of a part on my 04 xc70. It has a hose from the air filter housing and another larger hose that goes down by the radiatior and another hose that goes to the engine. It is mounted to the side of the air Filter box and has an electrical connection. I thought it might be the turbo boost solenoid but when I look up that part, although similar looking it looks different .

: part pictured in the fore ground

Post by **jimmy57** » 25 Sep 2019, 11:33

That is the auxilaiy vacuum pump switch. It turns on electric vacuum pump for the power brake booster whenever the engine provided vacuum is too low. This is usually in the first minute of a colder temp start when the variable valve timing and ignition timing are at settings that reduce the engine manifold vacuum to a very low level. The turbo control valve has three hoses that are about 10mm OD. It should be clipped to the air cleaner housing to opposite (backside) where this vac switch is located.

Note: that vac switch is guaranteed to break one day. If you remove it and use JB Weld metal filled epoxy and spread it around the sides to the bottom of the larger round potion as viewed in photo, it will go past the click tabs that hold the switch diaphragm chamber together. If you remove the switch and look , you will see the snap together tabs aand one will most likely already be broken. If you buy a new expensive switch from Volvo it already has been epoxied. I use the 5 minute cure version and after about 3 minutes of it being on switch it gets firmer. I wrap electrical tape around the epoxy band and it makes the repair look much better instead of looking like chewing gum was stuck on it.

jonahjays · Post by **jonahjays** » 25 Sep 2019, 12:10

Wow, Thanks JIMMY!

dono · Post by **dono** » 03 Feb 2020, 16:56

jonahjays wrote: ↑25 Sep 2019, 11:19 Hi All, I am looking for the name of a part on my 04 xc70. It has a hose from the air filter housing and another larger hose that goes down by the radiatior and another hose that goes to the engine. It is mounted to the side of the air Filter box and has an electrical connection. I thought it might be the turbo boost solenoid but when I look up that part, although similar looking it looks different .20190924_095841[1].jpg

I broke this once replacing the light bulb of all things. I was in a parking lot and just used electrical tape to hold the spring-loaded top down having no idea what it was. The tape lasted about 7 months then it failed and cause the booster pump to run continuously. I decided its a cheap enough part to just go ahead and get a new one rather than do the epoxy thing. On a side note I did just replace the Volvo Boost Pressure Solenoid Valve you mentioned and it solved Cat codes and evap codes that had haunted me for 18 months. $25 for the TCV!