Hey all, me again! Who would've guessed lol.
anyways long story short just installed new upper radiator hose, thermostat and felpro thermostat gasket. Bled radiator for 30m+ and went for a drive.(20minute drive @ operating temp) My cooling system is not building pressure but i am also not overheating so that's good.

Before all of these repairs, i was building pressure, squeezed hose, felt pressure in system. All good.

i replaced upper rad hose because the inner wall blew out and created small leak. Which caused the old hose to be soft when squeezing at operating temp. Like I said it's been replaced since then.


Is there a chance that even a micro bubble will cause it not to pressurize? Also the gasket surfaces were cleaned well and all of the old gasket material was removed.

I suspect the problem could be at the gasket OR there is air in the system still. Will a pressure test reveal a bad gasket seal at the t-stat on the upper end? Or does it only test the radiator/waterpump on lower end. Since thermostat is shut at cold Temps.

like I said, Thermostat IS working, upper hose gets hot, temp guage stays in safe zone. 195-200 Just not building pressure. Any tips?

Edit: my rad cap is less than 2 years old shows no signs of wear. . Heat works. Seems like everything in the loops is getting coolant flow. Im dreading doing the thermostat housing all over again if its the gasket. Are their any tricks to burping these? I mean I just put a new radiator in last month or so and bleeding the system was very quick, and easy. Hoses pressurized right away first drive. Been pressurizing up until today when I did t-stat, gasket and upper hose. I even parked on slight incline revving at 2500 rpm. I noticed micro bubbles coming out when squeezing new upper hose. ( im Using a bleeder bucket, with the attachments that screw on where cap would sit). These micro bubbles would come out when I would squeeze softly, and then quickly release. 2 or 3 tiny bubbles would float out. I did this for about 30 minutes on an incline.

 

The system partly uses heat expansion to pressurize. It is unlikely you will see pressure until the vehicle sits overnight. At that point, as the coolant condenses more coolant will be drawn in from the overflow bottle. Then the next time the engine heats up, the expanding coolant pressurizes the system, assuming there are no leaks.

 

As long as you didn't use a Failsafe, your thermostat should be working fine. You may have an air bubble in the heater core. Drive it a bit and see what happens. Place some clean cardboard down to make sure you don't have any leaks.