Coolant is returning to reserve

Normally this is due to a restriction in the cooling system but we need to start with looking for leaks, and excess pressure.

So let's pressurize the system and see if it holds pressure. Here is a guide that will help with this:

https://www.2carpros.com/articles/radiator-pressure-test

If it does then we need to test for a blown head gasket. Here is a guide that will help with this as well:

https://www.2carpros.com/articles/head-gasket-blown-test

We don't have a manual on this vehicle but this issue should be general enough that we can assist with this info and not need your vehicle specifics.

Let us know what happens with this and we can go from there. Thanks