2005 Passat TDI 130 Highline Huge Loss of power high pressure in rocker cover

[ditcher]

Hi,
I bought this 2005 Diesel Passat estate 130 Highline about 18 months ago. Its the B5.5 variant. 3BG or maybe 3B6 (Couldnt work out if the last Character is a G or a 6. From memory it's an AWX engine.

When I first bought it, I noticed oil leaking slightly from an assembly with an actuator arm that is connected to a vacuum diagram by a thin vacuum pipe that connects to a vacuum above the turbo. The assembly that is leaking oil is made of cast aluminium and just above the inlet manifold. (I was a mechanic in 1970s and 80s and don't know a lot about modern diesels.)
I looked to me that pressure was blowing oil out of the union between this cast aluminium part where it joins on to a hard rubber connector. The engine smelt of exhaust fumes but the exhaust wasn't and still isn't blowing. Fearing a possible blown head gasket, I removed the oil filler cap from the rocker cover and it was blowing out of the oil cap with as much pressure as at the end of the exhaust tail pipe in my estimation. Of course it was blowing a mist of engine out and I quickly put it back on after noting that there was no creamy mayonnaise visible. So I figured that the pressure was from the crankcase and a breather was blocked.

The car drove very well and I was getting 55 MPG and plenty of power but as its done over 180,000 miles I drive it gently and never rev it very high. It had a new cam belt at 160000 but its an older car and high milage so I drive her gently. I changed the oil and all the filters a few months after I bought her and ive done nearly 10,000 miles since I've owned her so I was planning to change the oil and the filters again soon (I use semi synthetic long life oil of a good brand and the correct type) I regularly check the oil level as my oil level indicator light has always been on and I understand this very common. The oil level is always at full, I have never had to top it up once even.

Here's the problem...The exhaust fumes smell has gotten worse and in traffic, I once got a headache. Then it started sounding like the exhaust was blowing and started sounding like an old VW beetle engine at start-up but once driving the noise was not noticeable, Over the past few moths it has got progressively louder and running rough at idle but drove completely normal. A couple of weeks ago, I started the car and I thought the the exhaust down pipe had was no longer sealed at the manifold flange. I drove the car and it was loud and it would not rev and the engine was juddering as if an engine mounting was loose or worn out. WE went to the shops for 15 minutes and when I started her up it had gone much quieter again and drove a normal for a couple of weeks.
Last weekend, I was about to go on a longer journey and a lot of motorway driving so i checked the oil and coolant levels and tyre pressures and with the engine running I carefully felt around the exhaust flange and I could not feel any blowing. The car was idling for 10 minutes whilst somebody I know came over to speak to me and then another person I know came over so the car was idling for 15 minutes and the temperature gauge was at normal. I checked again for any leaks from the exhaust flange and the exhaust manifold and felt nothing so I turned the engine off. I heard a hissing sound like air or pressure escaping and it gradually subsided but took over 5 seconds to gradually stop
5 minutes later when I was leaving on the journey, I started the engine and started driving and when I put my foot down, I had no power and the engine was barking and juddering really badly. I even thought the mains or big end ng had gone because the noise was a similar sound when i put my foot down hard to try and clear it.
I know its something to do with a PCV or EGR valve or breather coming off of the rocker cover is clogged up. I have tried to find answers on Google but I don't really know exactly what is blocked or faulty so I cant type in the correct query to get a useful answer.

I live out in an isolated rural location so I cant walk anywhere and there are no buses out here so I keep using the car and it still drives as long as I don't need to rev it over 2000 rpm. I really need to get to the bottom of this and be able to fix it myself as long as I can do it without removing a ton of components to get to it. It seems like it might be blowing back out of the air box but thats not for certain but i know enough to know that the pressure building up in the crankcase must be finding any possible any it can escape now and if there is any valve overlap, wouldn't it try to escape though the inlet manifold?

I feel sure that somebody will read this and know exactly what the problem is and tell me if I can fix it myself. My average fuel economy figure has dropped down to 47mpg and it till starts on the button and drives but steep hills are getting difficult and noisy. Im not getting any engine warning lights at all (apart from the yellow "check oil level warning light" that has always been on.

TIA Ditcher