radiator pressure build up

[tercelite]

can any one tell me why a radiator is building high pressure. my radiator is dripping coolant in the reservoir abnormally high. i change the radiaotor cap, thermostat,hoses and flush the radiator already. i even bleed it to remove air. when i removed the radiator cap during bleeding it, i can see the coolant flowing. what are some possible causes for this pressure build up?

thanks in advance

[Tercel GTS]

Possible head gasket troubles. You can have this tested at a shop with a special dye without removing any parts.

[tgidavid]

How high is the pressure? Usually the pressure in the cooling system is around 12-15psi.
When it bubbles over then your most likely culprit is a faulty water pump. When coolant doesn't flow easily, then the excess heat builds up and blows out of your cooling system.

[tercelite]

thanks tercel gts and tgidavid for quick response. there is new head gasket but still original water pump. i will try changing water pump and will keep you posted on the result.

[Paseo15psi]

Do you have the original radiator cap? That helps to control the pressure of the system.

[tercelite]

i installed new water pump and new radiator and still the same problem-- coolant coming out of the reservoir. Can the original cap rated 13 psi be replaced by say 15 psi?.

[Paseo15psi]

Yes it can. I have a 1.3 bar TRD cap on mine.

[Tercel GTS]

You really ought to have that dye test done before continuing to spend money on other parts you may not need. Only takes a minute and is cheap.

[tercelite]

i think the problem is solved. The new thermostat i first installed was the cheap one with no air bleed. i put a new one like the original and the engine even runs cooler. thanks a lot guys.