PCV Upgrade on my Volvo 850

The PCV system (positive crankcase ventilation) in cars is set up to vent pressure that builds from the rotating parts in the engine. In turbo charged cars this pressure is compounded with blow by, air forced passed the piston rings. For my car, running higher then stock turbo pressure, along with a fairly high millage engine, the OEM system has a hard time keeping up. The result is oil being pushed passed seals, and into the combustion chamber leaving me with trails of blue smoke.

To solve this I beefed up some of the tubing and added my own breather with a liquid catch can.

If you look closely you can see the black plastic box tucked next to the engine block, it has a few hoses going into it. This is the oil separator. It’s job is to recalim and oil vapor that may try and escape with the vented air/gases. The vent port that is closest to the outside part of the box is a nice 5/8″ port, but the vent hose used is reduced to something much smaller. It can’t be seen in this image as it has a foam jacket over it.pic08

My solution was to add a much larger hose, one that can take advantage of the vent port on the oil separator box. I used 5/8″ power steering return hose. A hose that is oil safe must be used, otherwise it will rot away in no time. Using a shot piece of hose and a 90 fitting i was able to direct the hard to flex hose into the direction i needed.



The oil catch can i used came fitted with 3/8″ ports, not quite big enough for this new hose. So i went ahead and tapped it for a bigger fitting. I retained the 3/8″ fitting for my vented oil cap.



Here is how the new hose will be routed. It’s carefully routed around the charge hose so it did not kink or cause any constrictions in flow. The catch can is next to be upgraded, either with a whole new can or tape a larger fitting into the top to handled a filter with a larger ID. This filter has a 3/8″ ID.


The end result is what i was looking for. No more smoke when i get on it. The car is tuned to 17 pounds of boost, but just hitting 14 would cause me to burn some oil.

This entry was posted in Automotive, Maintenance, Modifications. Bookmark the permalink.