Under Pressure

I have a 01' Ranger with a 2.3L m/t. I am having trouble with pressure building up in my pressurized coolant system. I have done a flush and filled with coolant let run with a bypass of to rid of air and after my morning drive my coolant develops pressure. It is really noticable in the upper radiator hose as I have had to replace it because of a bulge. Any help would be greatly appreciated.

All cooling systems are pressurized to some extent in order to raise the boiling point. Besides the temperature, the water pump is the only component that may exert some internal pressure through circulation. If your system is over pressurized, your radiator cap should've popped to relieve pressure. Did the upper hose bulge again after you replaced it. Also check your thermostat for proper operation and temperature setting (normally 195F).

like he said. radcap and check on that thermostat.

If the system is too full cold it will have no place to expand hot.

If the system is overpressurized, I still don't understand why the cap (if it has the correct setting) does not pop as it supposed to do to protect the system. I don't know about being airbound. Any air in the system should be relieved thru the overflow.

If your cap is defective or corroded it wont pop. As for the coolant overflow - is the line clogged?

Could it be that the bubble was caused by a bad hose? How do you know the system is "overpressurized"?

All cars have pressure when you shut them off after warming up, and a bad hose could bulge. Unless his car is getting hot overheating or losing antifreeze I would guess there is nothing wrong

Some pressuration is normal in a coolant system. It is designed to raise the boiling point of the coolant so it won't boil. I believe tha cap is rated at around 12 psi. A clogged overflow is easy to detect - simply look at the level of the overflow tank. Assuming that the cap is OK, and that there is no clogged overflow, and the coolant temperature is within range (normally around 210F) and you still suspect overpressurization, best is to get a loaner radiator cap pressure gauge. Install this gauge in place of the regular cap -see how much pressure it reads.