Heater valve is manual and can be opened with the temp knob. I assume i need to open the vacuum water co*k as that's the area which needs to be tested? how do u get vacuum without running the car?

You do not get vacuum.

The system pressure will equalize without opening the valves, there's coolant on both sides.

If you start the engine and let it get to temperature you'll generate pressure.  The main concern would be that if there is a leak, it will be hot coolant instead of cold.

11 minutes ago, Zed Head said:

The system pressure will equalize without opening the valves, there's coolant on both sides.

If you start the engine and let it get to temperature you'll generate pressure.  The main concern would be that if there is a leak, it will be hot coolant instead of cold.

I am thinking to put like 1G coolant in the system before testing?

What testing method will you be using?

https://www.oreillyauto.com/detail/c/evertough/tools---equipment/rental-tools/air-conditioning---cooling-rental-tools/12095d53bcad/rental-tools-evertough-radiator-and-cap-test-kit/ren1/67085

I was thinking of renting this...put 1G of coolant and get the pressure up to whatever is on the radiator cap and see if it holds up?

That's a lot of money for a one-time test.  Why not just fill it with water, start the engine, and see what happens?  Worst case you spill some water in the cabin.  Put a towel under the valves and cleanup should be easy.

22 minutes ago, Zed Head said:

That's a lot of money for a one-time test.  Why not just fill it with water, start the engine, and see what happens?  Worst case you spill some water in the cabin.  Put a towel under the valves and cleanup should be easy.

The test tool is free, Orielly's rent tools for free.

Should work fine.  If there's no leak you don't really need to add coolant.  The ability to hold pressure will tell you.

But if it doesn't hold pressure then you'll need to add coolant to see where it's leaking from.  Unless you have good ears and can hear the air hissing out.

I'm going to guess though that you might have problems getting the cap to fit correctly.  Just the odds, the right size and fit might not be in the kit.  You might get lucky though.

If it wont hold air pressure, a spray bottle with soapy water might help

You only need about 15#s of pressure for testing

Edited March 1Mar 1 by Patcon

40 minutes ago, Patcon said:

If it wont hold air pressure, a spray bottle with soapy water might help

You only need about 15#s of pressure for testing

If I hook up this thing to the radiator cap, dont you think pressure wont hold due to the overflow tank not sealed?

 

This is exactly what is going on what is shown in the video, everything was nice and tight. The old seal inside the vacuum **** is no good. That’s why the older one was also rusted. It only need a new rubber seal as well. It leaks between the two metal mating surfaces as the coolant goes around the damaged seal. Heater valve was holding nice. No leak there. There goes $30 worth of coolant.

Edited March 1Mar 1 by MH77280Z