Hi guys, my forged 2.5 sti has developed an over heating problem.


When sat at lights, the temperature gradually raises and the fan does not kick in. As soon as the car moves again the temps go back to normal and goes hot again once sat idling at lights.


Am thinking it must be a faulty thermostat as the fan isn't kicking in, does this sound about right?


Have ordered a new thermostat, but don't want to fit it just yet incase its the water pump at fault etc.


Any suggestions welcome.

 

Sounds very much like, swap the stat and see what happens. Could also be the fans failed.

If temps come down as soon as air is flowing i doubt its the pump

 

Thanks for the reply. I thought it might be the stat.

Which antifreeze do you guys recommend? I can't seem to find the blue oem Subaru antifreeze for sale anywhere. Is there a good alternative to use?

 

I would check if the fans work at all.

 

whats the best way of checking they work? They didn't kick in when the temp rose high at idle

 

As a basic test, im sure if you connect the two green connectors under the dash/ steering wheel, start the car, it goes into a test mode. This will run the fans, boost solenoid etc

 

Turn the ignition on, don't start the car.

 

Have you checked the fuses in the fuse box under the bonnet ??

The fans are triggered by the ecu when it hits a pre set temperature, as long as your temp gauge is working correctly is unlikely to be your thermostat. Are your fans working when you turn your A/C on ??

Any decent brand antifreeze is fine, make sure its suitable for aluminium, it should state (OAT) Organic Acid Technology on the label.

 

Agree with Dubzy, a stuck or knackered Thermostat will send the car cold on open roads, whereas if it's controlling as usual on the go but heats up when stationary, it's more likely the fans not working. Fuse first.

 

I have had a hawkeye where both fans had failed. Make sure they are working

 

Hi guys thanks for the replies.


I'll try the green connector test in the morning, that would be a good indication if the fans are actually working or not.


Not checked fuses yet Dubzy, which fuse number is the the one for the fans?

 

It will display the fuse layout on the inside lid of the fuse box cover.

Try turning your A/c on and see if your fans come on as they should.

 

So did the green connector test. Only one fan started spinning, the one on the right hand side as you look head on at the engine. Is this the AC fan or the radiator fan? The one on the left did not spin indicating the fuse must have blown.

Lookong at yhe fuse box, there are a few for the fans. Which one specifically controls the radiator fan?

Thanks

 

Just look along the fuses and see which one is blown.

 

Checked all the ones I can see and none are blown. All the rest are relays, do they have fuses in too?

 

I've never had a relay blown so can't comment really.
if one fan is working I'd say it was probably something else that is causing the overheating.
does the car overheat in normal driving as in my experience it takes a little while in traffic or idling for the fan to actually need to kick in.

 

Neither of the fans start up when stuck in traffic and the temperature starts rising, and like I said only the passenger side fan spins when connecting the 2 green rest connectors under the dash. Can't see any blown fuses anywhere.

As soon as i get out of traffic and drive the temps go to normal again

 

I've had same problem with my hawkeye slow moving traffic temp rises to over 100 on my psi3 data monitor and once get moving it goes back down I replaced stat and hasn't made a difference thinking could be fans at fault

 

Is there any way you can wire the fans to the battery directly to see if fans work.

 

I have noticed on newage Impreza's, if it has aircon fitted if its not working, ie no pressure in the system it messes with the fan switching of the main fan, as the ecu takes coolant temp, speed & aircon as vital inputs to fan switching & weather it switches the main fan & the sub fan on, both fans should be on if the engine is 100 deg c or over, so if you have fans working with the green connectors connected, you must have either the coolant temp sensor, speed sensor or ecu fault.

 

Think he said only 1 fan comes on with green connector.

 

Sorted the problem, the problem was the fans had simply seized from lack of use, a sharp knock with a spanner on each of them made them both jump into life tested the car, let it sit in my garage at idle and they both jumped into life when at correct temperature.

going to do coolant change next weekend so will take the fans off and give them a good clean up.

am a happy chappy, glad that's been resolved

 

That's good!
what made you try hitting them?
​​​​​​frustration?

 

Haha almost frustration but not quite! Saw some guy on YouTube who lived in cold climates so fans were never in use. He gave them a sharp tap with spanner and they jumped into life... worked for me!

 

Looked at both fuses the day both are fine checked the a/c fan is turning well but the other fan wouldn't spin let it idle for ages got up to 87c on the data monitor what temp should it kick in at

 

Im pretty sure my fans dont come on u until around 95 degrees.

 

Must be airlock cause it was idle for ages and sitting in the 80s but if im driving in slow moving traffic goes up to 100 -108 is that normal

 

Had the same issue on my 2004 JDM Blobeye widetrack.
Was on an easy motorway drive, 8c outside.
pulled off to an A road and park on hard shoulder to adjust head unit settings. After 15 min looked at temp gauge and it was at max!
I nearly had heart failure, just started to see the smallest amount steam in the headlights and through side of bonnet and moved off immediately with the heaters on full.
cooled down fine. went out next day to try and check if fans were coming on, they spun freely but didn't turn on.
A light bang with a hammer and they started spinning and engine cooling as normal now.

What damage if any could have been done by letting the coolant get so hot that it was boiling (for about 20 seconds) ?
could I have warped the heads? would it be obvious if I had?

 

that could have damaged the HG so I would monitor closely now. Classic symptoms of hg failing are more than normal amounts of coolant being pushed into the plastic expansion bottle after running boost. It may not show immediately. I would keep it close to home until you're sure.
Trev