What is a PCV valve and what does it do? PCV stands for positive crankcase ventilation, when the pressure inside the engine is too high this valve opens and allows the pressure to be transferred to the intake tract. Given the engine crankcase is full of oil when the valve opens it can/will allow oil to flow through this valve. With enough heat cycles, engine pressure and oil this valve can degrade and even fail.

A failed PCV will be stuck open and engine pressure will be able to flow through to the intake tract and cause your engine to ingest oil. This will lower our fuel knock rating and can cause detonation and lowered engine performance.

Time Frame

Replacing your PVC assembly on your Ej25 will be around 15-20 minutes as long as all the hoses come free easily. After many heat cycles and being so closely located to the turbo, it is a given that the hoses will be a bit on the brittle side.

Tools

As with any install we will need a few tools to help us with our install. This one is among the easiest and least tool assisted installs. With the Pcv assembly being just attached by hoses and clamps.

I use a set of Mac pliers and Knipex to take care of these pesky hose clamps. Anything will do but these are my go to.

Knipex pliers set

ATE 5 pliers set

A good magnet tool is a great tool to have through any work but it can be exceptionally helpful if you don’t want to remove your TMIC.