E90 coolant leak

[Gabriel300]

Hey guys first time posting. Really need help. I have a 320d ant it seems that coolant is leaking from the coolant tank because of gas build up. I don’t know if its a head gasket issues or just the tank. Also car doesn’t overheat. No white smoke from exhaust. Also inside the coolant tank I can smell an exhaust smell. Well the smell is bitter it’s like an exhaust smell but I don’t know for sure also I changed the cap and bleeder valve for a new one.

[marvinstockman]

Exhaust gas is getting into the coolant and building up pressure. If we had an actual temp gauge, you might see fluctuations in engine temp with every escaping gas bubble.

[jclausen]

If there any combustion gases in the coolant system you have a head gasket or head problem

[zellamay]

The test for combustion gases in the coolant is cheap and easy. An auto shop can do it for about $30.