My brother has a 94 WRX. He was wanting the radiator hoses changed and since he works out of town, I thought I'd do it for him.

Hoses are changed OK and I've filled it with coolant and water, but I'm not sure if I've got air in the system or not. When I was putting the coolant/water in the header tank, I could hear the air hissing out of it OK and I filled it until no more water could go in it.

Started the engine up and let it run for about 10 minutes. Temperature gauge was up to working temperature and the top hose going into the radiator was really hot, but the bottom hose coming out was stone cold. The radiator was warm on one side but not on the other.

Is that the way it's meant to be or does it sound like I've got an air lock in it? When I squeeze the top hose, the bottom one is flexing and the level in the coolant tank is just going up and down (no air bubbles) and it's the same with the bottom hose.

I'd be grateful for some advise cos if I've killed his car, he'll kill me!!!!!

Thanks,

Alison

 

If everything was fine before then yes you have an air lock sometimes the heater matrix can be a nightmare to get all the air out.

Do not run it until it is sorted.

 

Eek!! What do I do to get it out? I managed to find a workshop manual online and it says basically to let it heat up, then cool down a bit, take the pressure cap off to release air, top up the coolant, let it cool a bit more check it, then let it heat up again.

Is that the right thing to do? (He's gonna kill me!)

 

Pretty much yeh, only open it so air comes out, not too much or water will come out. Squeezing the pipes can also help.

 

Thank you. I'll try it tomorrow in daylight.

 

is that the best way to go, as ive just changed my coolant and i think ive got the same thing,,,

 

Just want to check this sounds right.

I ran the car till the radiator heated up (though the fans hadn't come on). Stopped it and let it cool a wee bit then opened the cap on the header tank. It didn't hiss or anything (is it meant to?)

Checked the hoses - the top one going into the radiator was boiling hot and the bottom one coming out was pretty warm but not as hot as the top one.

Temperature gauge was sitting at normal working temperature.

Water level in the header tank didn't drop at all.

Does it sound like I've got the air out?

 

Procedure when filling the cooling system is to turn the dashboard temp controls to hot, this allows water to enter the heater matrix.

Bottom hose hot, lower hose cold, could be caused by a stuck thermostat (which might be caused by an air lock).

But since the lower hose is getting warm, the air lock might be out. It takes forever for the car to get to operating temp just from idling. Try driving it for 15 min, the hoses should either both be hot by then or your temp gauge will start creeping up.