Head gasket leaking

I do not trust that those products actually work and might even do more harm than good. I would just replace the head gasket.

Recently I had to change the coolant metal rail across the front of the block then I noticed water running down the back of the block underneath the manifold. I am trying to figure out what it is. Can someone please help and let me know what I can use to stop the leak?

Good morning.

Can you post a picture of the leak so we can see it?

There is no stop leak to add. They are useless and cause more issues by clogging up the radiator and heater core.

The correct repair is to repair the leak.

Did you pressure test the system? It may be a hose or the intake manifold itself.

Roy

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

https://www.2carpros.com/articles/car-is-leaking-coolant

No, I do not have a pressure tester. It just looks like that is where it is coming from to me.

Okay, then you need to rent one at a parts store and pump it up and use a bright LED flashlight to pin point the leak. Once you find that let me know or post a picture for me so we can continue helping you.

Roy