Overflow in reservoir

Hello,

Why did you make these repairs? was you car overheating? Having small amounts of coolant go into the overflow is normal, as the car warms up and cools off the overflow takes the systems expansion and contraction of the coolant. Has the overflow its filled up to the point where it comes out of the car altogether? if you are getting exhaust gas into the system that will also push the fluid into the overflow but that will make it completely come out of the car and you will also get high temperature readings and full overheating. A failing head gasket or head problem makes that happen. The shop that did the repairs should have picked up on that though. you should probably do a cooling system pressure test should be done. Your local AutoZone had a lender program for the tool to do that.
Let me know.
Tom

Hello , thank you for responding. I did all the changes my self because it was overheating and smoke was coming out of the overflow, so I did all the changes. it worked fine then all of a sudden it started heating up and leaking all the coolant through the overflow. I did the pressure test no visible leaks so I’m not sure. I changed the thermostat, the radiator, the hoses, but it’s still leaking the coolant completely through the overflow. haven’t tried changing the head gasket maybe that is why.

Hello,

Yes, smoke and not steam coming out of the overflow is evidence of the head gasket. If you when the car is cold, if you have the radiator cap off and you start the car if there's a head gasket issue you should see smoke or bubbles coming from the coolant. if you have water movement like that before the thermostat opening that's what is going on. if the head gasket is going bad but is slow to check that with the pressure test. Pressurize the system make a note of the pressure and let it sit overnight. if in the morning the pressure is not the same its the gasket.
Let me know what happens with the overnight test.
Tom

Yep, the head gasket is what I was thinking. these guides can help us find out what's wrong:

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

and

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Please run down these guides and report back.