Don't know why your removing pipes. There's 2 bleed screws. If you need to get air out then you need to check air is released from both screws. If it has over heated then you still need to check both screws. If it loses pressure the coolant in the engine will boil (if it's hot) creating air and this will only come out via the engine bleed screw. Have a look on this fred for how to bleed:Hippo,
Yes, the top hose from rad is rigid on high temperature.
When I changed the thermostatic valve, I tested the pressurizing system with air and checking on the gauge the pressure. The system had no leaks.I put 10 PSI and gauge the pressure stays in 10 min test. If the pressure rises above 16psi, the reservoir cap releases the air.
To bleed the system, I completed the reservoir and open the screw of heater hose getting out the bubbles. Then I removed the small hose from the cylinder head and let out the bubbles from head. Started the engine I pressed the top hose several times to help get the rest of the air out. After open the bleed screw sometimes.
This second bleed screw you talk is what is behind the block? This screw I opened a long time ago (6 months) when I changed the coolant. This screw I read it only serves to drain all the coolant from the block, and not to bleed the system, am I right?
I tested today removing the top hose from rad to see if the engine coolant outlet has flow (temp 98ºC on ODB scanner), and the results are the same as the video from another user. 98ºC the thermostat was already open and I think the coolant flow is too low. In another car that I have (S10 2.4 MPFI) when I removed the top hose from rad the flow was much higher than that.
The video does not have the answer which was the problem.
My idea now is to change the water pump, but it is work to a week now.
Nodge68,It might be worth checking the water pump for a plastic impeller.I've seen the plastic impeller come loose and stop spinning when the engine heats up. There's no need to take the pump out to check as the impeller can be got at through the thermostat link pipe if you use a dental mirror or cheap endoscope.
B34R,
I do not know this bolt in the engine rear bank, I tried to search but found nothing, very hard to access too.
My last chance is to replace the water pump, although check the thermostat tube it was good.