Inlet manifold nut

[l0stwhite]

What is the big 17mm nut in the front of the vn,vp,vr manifold a spring is
underneath it?

thanks brett

[Brett_jjj]

It could be the PCV valve.Its under a big nut on some of the V6 manifolds.

[delcowizzid]

PCV valve is under the spring

[WAFFEN SS]

What is PCV for those that dont no?

[Brett_jjj]

PCV- Positive Crankcase Ventilation.It allows a certain amount of filtered fresh air to circulate through the crankcase of the engine to scavenge any fumes in the crankcase,these fumes etc then go into the inlet manifold where it mixes with the incoming air and is then consumed in the combustion process. .When an engine is running,a certain amount of the combustion gasses escape down past the piston rings into the crankcase,this is known as blow-by.It slowly gets worse as an engine wears out.Years ago before pollution gear was fitted to engines, crankcases were vented straight out to the atmosphere.