The video started 2 seconds after I started the car.

 

But there are not any air bubbles. This can be normal? What happens if you guys open cap. Do coolant go up?

 

That radiator cap is designed to be pressurized up to around 16psi before releasing to the overflow resevoir. So as the engine warms up the pressure in the system is expected to increase. This is normal.
What was the reason for opening it while running? Overheating engine, suspected blown headgasket, coolant leaks?

 

No, I opened it first time for the day. First opened the cap, it was 2pm, then I went to start car and then went recording. If someone can do at his cold car same to se if coolant go up. But I do not see in video any air bubble. And idle that car for a while and it didn't overheat. Went to 1/3 of scale and stayed there. Reason for opening was because I bought it at auction and just like routine check. However, no air bubbles in video. How is with your cars guys if open cap at cold engine. It can be that water pump is strong in 3g.

 

This guy at 6:20 said do not get confused between water pump pressure and blown head gasket but do not explain what is difference. This is his
"The water pump will cause movement in the radiator because it produces 10psi plus or minus of pressure as the belt rotates the water pump pulley. Don’t get confused know the difference."

 

I would say now it is normal too. It started moving up 36 seconds after starting the car. If someone would test at his car on a cold engine. If would be blow gasket it would move up right away.

 

Ah, you're checking for a head gasket leak. Check the overflow resevoir when the engine is cold. If empty and there are no other coolant leaks present it could *potentially* indicate a blown head gasket.
A more precise and cheap method would be to buy a combustion leak test kit.

The coolant level rising is normal as the radiator fins are very restricted, its simply going to the path of least resistance. The water pump moves ~150mL/second when idling.

I don't think I saw a single bubble come out through the cap when the engine was running, you're likely just fine.

 

I just try to learn from Ziners. So, bubbles are the culprit? Yeah, I routinely opened it just to check for air bubbles.

 

What are you checking for? Just fill the radiator, add coolant to the overflow bottle and put the caps back on. Run the car normally. If you lose fluid, then you might have cause for concern.

 

Did combustion leakage test and all good. And water is steady when 1/4 of quart is taken off. I can say everything is fine there. Vill post a few videos and pictures.