pd170 bottom end whine

[Dan1425]

Hey guys, bit of a tricky one here! going to try explain in as best detail as i can!.

2007 b6 passat, pd 170 engine, saloon.
stage 1 remap, dpf and egr delete

after experiencing some running issues, i took the car to my local garage and the problem was found and repaired:
Cam sensor replaced
Rear fuel pump replaced
full service
Egr stuck open, blank plate applied

Car ran amazing for 2 days commuting to work.

woke up the following morning, started the car and then came a really high pitched whine in sync with the rpm from idle all the way up through the revs.

Here is what the mechanic tested and is NOT the problem:
Cam belt tension
All tensioners
aux belt, still makes sound with it off
turbo
all cam belt area bearings

After those tests, we discovered the noise is coming from the bottom end, inside the engine.

sounded like possible oil pump, replaced with a whole new unit and the noise is still there.

3 mechanics have looked at it and all have failed to find the issue.

when i looked last night, i noticed there is a lot of gases escaping from the oil filler hole when you tske the cap off. if you rest the cap on the hole and run the engine, the cap bounces around like crazy indicating too alot of pressure or gases escaping to there?

any advice would be massively apreciated. please do not get distracted thinking it is top end or turbo because that has been ruled out by 2 mechanics.

video link of the noise: pd170 bottom end internal whine noise

funnily the car is actually running the best it ever has been, full power and has plently of torque. no tapping or knocking.

im completely stumped, any help would be amazing right now!
only option ive been given is a new engine which is not ideal.

[DMitch16]

You likely have a gear driven balancer unit and it could be related to that. Perhaps the gearing is too tight between the crank cog, intermediate cog and the driven balance shaft cog. If it is a chain driven balance unit it could be a slack chain drive or worn chain tensioner. Perhaps something internally has worn in the balance unit to the point it is complaining.

Could also be a worn timing tensioner, or timing belt rubbing on something. Cams look OK? No marking or signs of contact at non contact points? AC compressor in good health if you have AC? Some Passats have constantly rotating compressors that utilise a swash plate changing the angle to promote pumping of the gas and levelling to cease pumping. These do not have traditional magnetic clutches to switch AC pumping on or off, it is basically on all the time but either active or inactive.
All need to be checked.

Finally it is illegal to drive a car that has had emission control parts removed or 'deleted' from operation. Oddly it is not illegal to remove or delete these parts, just to drive the car once it has been done. And we know the engines supposedly run better and are perkier etc., etc., but altering them like this increases nitrogen oxides NoX gases 40 fold, which is an invisible killer in built up urban areas especially affecting children who develop lung issues as a direct result. Some altered engines have prematurely failed after emissions parts were removed. My 170 has stock DPF, stock EGR blows way under the 0.50 VIN plate in the irrelevant MOT smoke test (it is a NoX test that is needed) and goes like a bat out of hell still at 232000 miles. No excuses for removing these parts imo.