So back my car up today to find coolant all over the floor. Popped hood and my reservoir was full and coming out of the tank.
2005 Wrx
Mishimoto radiator
Mishimoto hoses
Mishimoto radiator cap
OEM upper reservoir cap
30,000 miles on thermostat.

Tried to let it idle and have the fans kick on and they never did.
OEM gauge says normal heat levels
No coolant in my oil
any ideas. Anything I saw online was related to 2.5L and didnt match up to my symptoms

 

i would run the car with the heater all the way up and once it reaches to 210 degrees the fans should come on. if they do not then your fans or relay could have went out on you.

 

Nothing with the fans would explain the coolant overflowing...

For the coolant to be overflowing there either must be a restriction in the downstream line causing the fluid to back up upstream of the restriction, or, some other fluid is displacing the coolant in your system. Since you see no mixing of fluids I would suggest a restriction.

It could be that before you replaced your radiator... Etc... Some material got lodged in your coolant system and only now it has caused a restriction. The most likely place for the restriction downstream of the coolant overflow bottle would be the water pump.

Check the water pump for debris.

 

How about your thermostat?
Check and see if your bottom hose is hot after it reaches normal temp. If not then you thermostat isn't opening.
If your fan relays are still good then your fans are bad.
Open up your radiator cap and see if you see the coolant flowing.
Do you hear any sounds coming from your water pump?


Btw do you still have my gauges oil and water temp sensors?

 

I had the same issue with my 05 STI, It was AIR in the system. Try Burping the Cooling ststem W/ Heater on from Res. near Turbo, since it is the highest point.

 

So coolant looked foamy this morning. I burped the system and got it flowing again. Fan won't turn on so imma check electrical. Temps won't go about 198•

Quite possibly blew a head gasket. Guess I'll update this

 

fans not coming on can be caused by a thermostat stuck open. coolant bubbling out of coolant overflow, my blown headgaskets caused that. HG went out and was mixing with exhaust. killed my cats as well as my exhaust valves

 

Thanks. I have a replacement thermostat. In the past a CEL would go for it being stuck open. So I'll wait for that. In the mean time I will check coolant for hydrocarbons

 

well im jealous you have a code for that. if my bugeye RS has one as well, it never came on, just ran cold and wasted a good amount of gas. lol

 

1: mishimoto caps are crap get rid of them they could have failed buy some sti ones I have if need

2: thermostat could be stuck open and could be giving you symptoms of a blown head gasket

3: for fans check relays and fuses make sure the relays are seated all the way

4: for burping the system turn your heat on full blast don't know why but it causes your fans to turn on.

5: if all else fails head gaskets and arp head studs yay!!!

 

I'll keep an eye out. For now the problem is resolved. It was like a freak incident. Still going to try to track down what caused it.