92 jetta 1.6 na
When I top up my coolant every 2-3 weeks it is really hard to take the cap off then coolant rushes back into the reservoir.
What causes the vacuum?
Sounds like a faulty cap to me.
As the system cools down, it depressurizes and the cap is suppose to open to let the vacuum out.
I think VWs do this anyways...
It's the blue cap. Brand new 4 months old max
caps are cheap, I'd grab another and see if it fixes the problem.