14' 360 SV - loud squeal at hot idle

[yorkadam]

I am a relatively new, but not the first owner of a 2014 Caterham 7 360 SV. Wet sump. 2.3k miles.

 

At warm idle after spirited driving (commuting is hit or miss) the car develops a rather loud and annoying squeal / whine. Initially I suspected the usual suspects - belt and , pulleys , or water pump. So I changed the belt, noise remained. Sprayed the pulleys a little, no noise change. So after reproducing it I removed the belt and was still able to get it to make the noise...albeit a bit less shrill / deafening.

 

So far I can make the noise go away by pinching the vent pipe from the top of the camshaft cover - interrupting the vacuum - or if I remove the oil filler cap.... but not knowing the architecture of the duratect I'm pretty much flying blind. Could it be the one way check valve in that line leaking? Any other sources of a shrill sound on the driver side of the engine that are common? Water pump seems unlikely but I don't know how that might be impacted by the vent I'm pinching - could be it's inadvertently affecting idle in a way to make it disappear... But that correlation seems weak since its present without the belt installed...

Edited June 22, 2019 by yorkadam

[yorkadam]

Verified the idle air control valve is deleted as expected with Caterham.

 

Also when the engine cooled I removed the camshaft cover vent attached to the intake track, after the throttle body. I applied some positive back pressure... I was able to hear it passing all the way through the pcv and into the intake manifold. Is the valve inline supposed to be a check valve? Most PCV systems seem to have one in the system... But not sure since this is my first duratec and Caterham.

 

Also notable is the rattling sound coming from the "valve". Perhaps a spring has failed and thus is allowing leaks at idle?

[yorkadam]

Video of me venting the various parts of the pcv system with the car at warm idle... Revving just to keep hot... Noise is constant when the engine is warm: