Hi,

I have a 2011 chev aveo with 180000 kms clock.. its currently building up a lot of pressure in the cooling system.. The water is getting pushed out the water bottle. I have changed the radiator, therostat and flushed the system. The car does not over heat according to the heat garage, It sits at half way mark all the time and just kicks out the water through the water bottle once i stop after a long drive or if i race the car. Someone told me to look at the oil cap and stick too see if oil and water is mixing but it's fine. I'm not really sure what to do now. Please help

 

what is the radiator cap pressure stamped on it?

 

There is no cap for the radiator itself.. just a cap on the water bottle. That says 17 psi and 120 kpa

 

Can you do a compression check on each cylinder?

 

replace the reservoir cap.

if the cap does not seal the system it can't presssurize and raise the boiling point of the coolant. the end result is the coolant boils over at normal operating temperature....the coolant expands and gets gets pushed out the pressurized reservoir.

 

The pressure cap may or may not be defective , but it is a cheap thing to try .

The reason you were asked about compression test and oil mixed with coolant , is another answer is blown head gasket , cracked block or cracked head . This can allow high pressure air or exhaust to migrate to the cooling system .

God bless
Wyr