How does air/bubbles get in to the cooling system?

 

Thank you,

 

Gary

That's a really broad question - why don't you tell us what you are trying to fix (and maybe what you are working on!) and we'll try to help.

 

Bubbles in the cooling system might not even be "air" - could be exhaust gasses, etc.

 

GD

where are your bubbles? what car? what year?

thanks

bh

2002 outback 2.5, when the car heats up, then overheats the cooling fluid overflows into the coolant overflow tank and does not flow back into the radiator. When I pour the coolant from the overflow tank back into the radiator I can drive for a short distance then the engine overheats and the coolant overflows back into the overflow tank.

I recently replaced the radiator cap and the thermastat with genuine Subaru parts from the dealer.

 

Thank you,

 

Gary

if you didn't properly "burp" the radiator when you refilled it after the t-stat replacement that could be causing your problem. but since something (overheating?) prompted you to replace that and the cap it does not look good.

 

remove the cap (and vent on the other side,) and fill the rad. start the engine and let it run until the tamp gauge reaches normal temp. this should purge the air out of the system. refill the rad and cap and seal. fill the over flow to the max line and you should be good. unless you have another problem.

 

it may help to have the front end of the car uphill, but not required. but having it down hill would be a mistake. haveing the vent open when filling at the cap will allow more air to escape and help the process. it may be helpful to fill the last bit from the small vent on the driver side of the rad.

Your head gaskets are shot.

 

GD

Your head gaskets are shot.

 

GD

 

Indeed, check out my recent thread on the same issue....

 

Steve

could have started with an overheat due to radiator issues, thermostat, air in the system....then the overheating may have caused the headgaskets to let loose.

 

so - be sure to clean out the radiator, replace/test t-stat.

unless you have an after market radiator the vent is on the top of the rad, passenger side at the top hose. it has phillips head slots.

 

see pic.