Cooling system excess pressure.

[nizmo]

Hi. I searched this but could not find anything. Sorry if it already exists.

I brought a v7 wrx on the weekend. It has had a full alloy radiator installed recently. I test drove it and checked it over and it all seemed fine. I drove it home 5 hr trip. Coolant temp fine all the way down. Checked the coolant level following day and was down a bit. Went for a short trip today and noticed the top hose was very hard and coolant was leaking from around the cap. I replaced the cap with a new one and this is still leaking. The top hose is rock hard. Does this seem to be a head gasket issue?

Edited April 21, 2016 by nizmo

[lachlan]

It might be the cap is fkd . Well if its leaking then it prolly is . Where is it leaking exactly ? And is it a stock cap .

[SpeedySub]

Is the bottom hose hot as well? If not there could be something wrong with the radiator (potentially blocked?). Have checked to see if it has all the air removed from the system.

[dmacnz]

Check that The rad fans are working.

If that's ok. Possible head gasket.

[Firenza]

I hate to say it, but probably head gaskets. I've had it happen before and am currently dealing with a ej25 with the exact same issue.

See if you have someone who can do a hydrocarbon test (not a tee Kay test, those are useless on subies) that will at least give you a definitive answer.

[nizmo]

thanks. new radiator so not blocked. new rad cap. std pressure one. top and bottom hoses just as hot as one another. its leaking all around the seal of the cap. and the fans are kicking in. i contacted the seller who had no hesitation in paying fot the repair. he will pay parts and machining and ill do the labour. i am a mechanic and im sure it is head gasket but just wanted to ask here first. next question. where to get cheap arp head studs and what head gasket to use???

[nizmo]

Update. Engine was pulled and heads stripped off. Both head gaskets were gone. Machined the heads and the block. Apparently boost pressure was making its way through the head gasket in to cooling system but the radiator pressure was not enough to get in the the cylinders. Caught it in time.