Superb_Owner_1

The sound and behaviour of mine right now is exactly the same as it was in the very first post I wrote back in August last year. I just checked and the vid attachment in the post which still works.

Interesting, thanks.

Is that behaviour after the removal of the plastic washer on the pcv diaphragm? Thanks

I've just made the videos pretty short, and I think you can usually degrade the quality in your phone video editor

Curious, interested to know how you get on with the mod.

My car has never had a fault code in relation to the evap, crankcase ventilation or air / boost leaks. The pcv valve was changed twice on the old engine and the same humming sound always occurred, it is also present exactly the same with the new engine. My current speculation is that there is a small air leak somewhere in the evap system below the threshold which would trigger a dtc. But at this point it remains speculation and I'm continuing to monitor for any changes in symptoms or behaviours which would support or rule this out.

In mine air pulses into and out of the holes as the diaphragm oscillates and this is what I think creates the characteristic humming sound. There is no overall leakage of air volume in or out of the holes which leads to the conclusion that the diaphragm is not perforated.

One thing to note is I think there is an earlier and later version of this engine, mine I believe is the later where the evap is routed to just upstream of the compressor, I think in the earlier version it is routed to the pcv valve on the valve cover. The pcv on mine has a blanking plug where the evap pipe would have connected. Whether this is relevant to the behaviours observed I've no idea.

I'll post any updates too. I'm sure the humming from the pcv wasn't present when the car was new until around 10k miles or so which is when all the issues started, they were subtle at first getting progressively worse over time.

Yes, there is a fair amount of suction at the oil filler cap when the engine is idling, and some at the dip stick too. Removing either when the engine is running results in increased idle speed. I think this is normal, however what is considered to excessive vacuum in the valve cover I don't know. The vacuum level has never been measured on my car and I don't have a reference valie for what the normal range is. What I can say though is that after the engine has been operating for a while, say several long journeys, the dip stick is really hard to remove, for instance to check the oil level (engine off obviously). I'm not sure if this is just a design issue or whether there is excessive vacuum which is pulling a small amount of air past the dipstick seals and drying them of oil.

One question I have is whether anyone with this engine notices there never being any vacuum in the fuel tank? I thought it was usual for there to be some vacuum on petrol cars as the vapours are pulled into the intake. When removing the fuel filler cap on my car after short or long journeys three is never any air in rush into the tank.

Yes there is still quite a lot of vacuum in the valve cover, I think some is normal, and the pcv valve still hums.

This was the whistling noise on the car's original engine 20231121_084658_1_1_1_1.mp4

I did find a video on YouTube for a symptom I have observed on my car which is a knocking sound coming from the evap purge valve. The video shows the evap pipe from purge valve to carbon canister is split, I checked the pipe on mine in the same area but could not see any visible failures. https://youtu.be/EAz9wVGhEv4?feature=shared

Hi, Quite a lot has happened since my last post. The engine in my car continued to worsen in terms of driveabilty, it also started to whistle loudly when hot from around the intake pipe area just before the turbo compressor, and it developed a significant vibration. As well as continue to exhibit all the previously symptoms I posted about. The vibration was traced to a failed flywheel, and failed thrust washers on the crank. The latter resulted in significant amount or metal in the sump and metal particals in the oil. The engine has just been replaced under warranty including the turbo. With all the diagnostic work and learning over the past few months I'm pretty sure that the pcv diaphram had never actually failed, by that I mean perforated. For some reason it's made to oscillate causing the humming sound. Even with the new engine the pcv valve still has the same humming sound which stops when you put your fingers over the holes, and you can hear the sound decay when the engine is turned off as the inlet manifold pressure increases. Despite the new engine in mine I'm still not convinced it's running quite right as it feels down on power but it's still running in so I'm holding back on testing it at this point. The steady state torque control instability and whistling sound have gone, as well as there being a significant reduction in nvh from the engine. My thoughts are on the pcv valve humming is that there is a small air leak somewhere in the evap or crankcase ventilation piping but nothing has been found to date (and there has never been any fault codes relating to it). And this may also explain why the engine feels a bit down on power. I'd love to know if anyone else has experienced this humming sound from the pcv valve and if the cause was found, I'm sure it wasn't as loud as it is now when the car was new.