ASZ with a blown head gasket?

Have a nice day!

My Audi A3 with the ASZ engine is causing me some concern lately. Specifically, I often hear the well-known "gurgling" sound on the passenger side after turning off the engine. I've read many topics in this forum and have learned about similar symptoms in AJM engines. According to that, it was usually a defective head gasket that caused these noises in the heat exchanger.
Well, that wouldn't be a very encouraging diagnosis...
Interestingly, I also heard these noises last summer (2005), but I didn't think anything of it at the time. Since then, the car has driven over 35,000 kilometers more. I have never experienced coolant loss before, even though I drive on the highway several times a week at speeds of 160-180 km/h (I know that in Austria, the speed limit is actually 130... ).
This morning, I also opened the expansion tank with the engine cold and couldn't detect any gas leaks or anything else unusual. The coolant level always remains consistently at the optimal level.
My question is actually just how I should interpret these sounds now. Can I already expect a ZKD (zero-knowledge-proof) issue, or could there be other causes?
Last summer, I replaced the coolant temperature sensor and had to top up the coolant. About 6,000 kilometers ago (at 92,000 kilometers), the timing belt and water pump were replaced. During that procedure, any coolant that was lost would also need to be replaced. Could it be that there is still air trapped in the cooling system after this procedure, and that this is causing the noises to recur?
Is there a way to safely bleed the entire system?

Sure, here's the translation:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which translates to "Sincerely" or "Best regards" in English.

Hi.

Yes, air can enter the system during the types of work you're describing.
Normally, the engines should bleed themselves by simply letting them idle for a while (until the radiator fan turns on, which indicates that the main cooling circuit is also filled).

But could the humming sound possibly be coming from the air conditioning unit?
So, if you turn off the engine, it's not coolant that flows in, but rather a refrigerant?

Is there enough refrigerant inside?

Greetings.
m;

Thank you for the quick response!

I've never let the engine idle for so long that the fan turned on, but I thought they also bleed air during normal operation? But I'll try that too.
The suggestion regarding the air conditioning could also be... From yesterday to today, I explored the galaxy using the ECO drive, and I couldn't detect any unusual noises .
Okay, I'm going to try driving with the air conditioning on and then off, alternating between the two, and see how it affects things.
While I couldn't complain about the lack of cooling performance from the air conditioning, I would prefer a lack of refrigerant to a blown head gasket .

Sure, here's the translation:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which translates to "Sincerely" or "Best regards" in English.

I had the air conditioning system serviced. It should be done regularly, and then you'll know if that's the cause.

The cooling system should also be able to vent air during normal operation. Normally, you would work on the cooling system after doing other work, but as Dieselmartin already mentioned.

Hello,
I've had that issue for 3 years already.
Comes from my climate control system.
Even after topping up the coolant, the gurgling sound persists.
Don't worry about it.

Best regards,
Jürgen

Hello.

It comes from the climate here.

Normally, the air conditioning system doesn't 'gurgle' after being turned off; a 'hissing' sound would be more typical for the air conditioning.


Don't worry about it.

I would rather investigate the issue with the head gasket further - my AJM is also making strange noises at the moment.


Regards,


hb2000