Passat B6 1.9TDI BKC 105km 2k5: Head Gasket Replacement, CO2 in Coolant, Leak & Regeneration

Welcome.
4 years ago I had the head gasket replaced.
About one month ago
The car started to say that there is no liquid. After unscrewing the cap, the pressure pushed the liquid back into the tank. I bought a CO2 tester I checked
and it turned out that the engine pumps CO2 into the liquid circuit.
The mechanic dismantled the heads and showed me that there was no sign on the gasket where this leak could be and the head was not cracked. And he told me that the screws were very poorly tightened (that is, they could have previously installed the old screws and this is the result).
He installed new gaskets, bolts and assembled, at the same time he replaced the timing gear (40kkm skf pump slightly oozing the belt slowly could be replaced).

After 60 km, the fluid tank was empty. Again all the pressure was pushed into the hoses.

Head imported for regeneration. Checked for leaks (apparently it was so curve that they barely screwed it to the table) replaced valve bushes, sealant valves.

The mechanic replaced the seals on pump injection, seals and thermostat because he noticed that it was broken. He noticed this when, after reaching + 90C, the liquid began to bubble in the tank.

I picked up the car today. The Lord took nothing but work for part. The exhaust fumes smell strangely with some indefinite biting smell (in my opinion, like a burnt liquid from the radiator)

I drove 20 km and the pressure tank built up in the liquid tank and the tester (bought from an automotive store) turned blue from yellow again.
The mechanic said that this pressure is a normal phenomenon and I have to drive. And this tester may be broken. As I have a second one purchased on the Allegro website, I am going to check if something like that happens. After installing this tester and after adding gas, you can see a little bubbling, and when you release the gas when the engine goes out of rotation, you make one big bubbling like in a jacuzzi.

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edit

I checked the same fluid from another source


The man who regenerated my heads said to check that the piston sleeves are not cracked. I told the mechanic about it and supposedly checked it. He showed me that he poured water into the water channels to the full and there was no rust trace in the combustion chamber.

2700 dumped in the mud and the car was broken so probably still broken.

The mechanic said that if he breaks again, he spreads his hands because he doesn't know what it can be.

Check cylinder pressure and provide results.

The mechanic checked the exhaust gas cooler?

Unfortunately not. Tomorrow it will only be checked

Change the mechanic after 1, on a metal gasket with a small blow you rarely see it, damage the gasket once. He didn't take money from you the second time, because I think he came to the conclusion that he gave the body without giving the head to check and plan! (work, your money and your ass)
Recently in Sharan BVK also spilled liquid, after the seal nothing could be seen, only the guy from the head said that the second one was flushed valves.

A colleague above suggests well.
I think you found the answer in the movie you added.
I am already afraid of checking it tomorrow, flooding it with water for the night
There is nothing to check here, you just need to buy a second, even used, cooler for the test, that you could bypass it and then do a CO2 test, but the game is not worth the candle, because the drug does not even cost a hundred.

On Tuesday I replaced the cooler with a used one. So far, co2 is not available. The pressure doesn't build up.
After dismantling, you can see some strange coating on the lamellas inside. As if sediment / stone




But there are still more problems ... after the weekend where the car was standing and was not started, something started roaring. Namely, while driving the 2.3.4 gear from 1300 to 3k (then you can hear) when you step on the gas pedal you can hear a roaring sound like an owl. Idle nothing while idle and while driving

And I think that this pressure will not build up anymore.
To be sure, take a CO2 test after a few days of driving.
What you are showing is probably the glycol residue from the coolant.
As for the roaring, after your mechanic I would check all the intake connections, starting from the air filter to the exhaust connections. Turbo, radiator, exhaust