Hey guys, still having random overheating problems, it will run stable for a while and then out of nowhere the temperature gauge sky rockets, also when I turn the car off the coolant is still going around the system, undo the bleed valve near the ecu’s and coolant still spurts out, the reservoir is also having coolant spitting back into it. This continues for a few minutes before it stops. Thoughts anyone? https://youtube.com/shorts/ZUFkKDPGNv4?is=qVfqNQxoPOcvTFWb
also when I bleed the sytem using the bleed point near the ECU’s it has a consistent flow, this indicates that the system is pumping coolant around, but the reservoir runs low before any air comes out, can I bleed the system with the reservoir lid off, as someone on a previous thread said that it’s a vacuum system and the reservoir lid needs to be on to create vacuum. when it does overheat with the reservoir lid on the coolant reservoir starts to fill above the max line.
In my opinion, you have air in the system. It’s normal,that the coolant flows for a bit when engine is turned off. In my expirience, properly bled system leads to the return chamber in the coolant reservoir be always filled with coolant (even after engine is off and it stays off for as long, as it needs to cool down fully)
Run VCDS output tests for coolant pumps V50 and V51 to see if they are working properly.
If they do, you should check if thermostat is working correctly.
Also note - the engine shows it’s at operating temp at around 75-115 deg. C. The gauge shows overheating pretty abruptly after going above 115 deg.
Also, the coolant should be at max mark when cold according to the repair manual, and can be above max when hot. In my expirience, for the system not to release coolant, it should be in the middle between min and max when cold, and goes around 3/4 MAX letters height.