Everything You Ever Needed To Know About Cooling Systems

[impr3vize]

That was beautiful. I have tears in my eyes!!! NICE WORK SOLBEY!!!! a+++

[Patrick Olsen]

Originally Posted by solbey11

Coolant: Subaru recommends using their own Genuine Long Life Coolant/Antifreeze in all Subaru vehicles. According to Subaru, this genuine coolant contains antifreeze and anti-rust agents that are especially designed for the Subaru engine. Primarily because of its aluminum crankcase [... what?]. They claim that other coolants may cause corrosion within the Subaru engine. They also do not recommend using any additional anti-rust and corrosion inhibitors.

The local dealer in CT told me they only use the Subaru coolant for warranty repair work, that they don't bother using it (since it costs about 2x any other coolant) on older cars. I can't say I've seen any adverse effect of using non-OEM coolant after 180,000 miles.

Originally Posted by solbey11

A normal combustion chamber will experience temperatures from 1500-4000 degrees F.

4000degF? I'm curious where that number came from. I've heard of EGTs as high as 1800 or 1900degF, but 4000 seems awfully high, like the combustion chamber is melting high.

Originally Posted by solbey11

4. A stock radiator cap is designed to only hold 16 PSI of pressure. The STi cap holds around 19 PSI. The extra pressure created by these caps will most likely cause radiator failure when used on a stock cooling system.

4. Also, stock radiators can only handle up to 16PSI of pressure. By adding an aftermarket radiator cap, it’s been know to burst the radiator end tanks.

I have to disagree with this bit of info. I've been using an STI cap for tens of thousands of miles with no issues, and I'm certainly not the only one. SPT sells the STI high pressure radiator cap, and I can't imagine they'd do that if the thing was going to rupture the radiator. I don't know about the newest models, but in the GC body style from what I've seen the 2.5RS used the same radiator as the JDM turbos did. Unless they were equipped from the factory with a radiator that was liable to burst at any moment, I think it's safe to say the STI radiator cap is going to work just fine.

Originally Posted by solbey11

Coolant Temperature Sensor – It also relays the temperature back to the instrument cluster letting the driver know the operating temperature of the engine.

Just for clarification sake, the CTS doesn't send the temperature to the instrument cluster. There's a separate sending unit for that - the one with the single spade connector on it right next to the CTS. You can see it in your picture.

[Kostamojen]

You should probably include the two different types of Water pumps for EJ motors along with info about the OEM oil cooler too...

[RUSHTK]

I get to replace my heater core, now I just need to find it and I bet it will be a bitch to replace! Thank you for the excellent write up!

[johnny-o]

Originally Posted by Woki Toki

awesome write-up, I think we should have a write-up section or like an informational section in the forums for these kinds of threads.

agreed. and sticky this!

[25RSsubaru]

Maybe you can add that the 2.2l takes 6.2 quarts and the 2.5l takes 6.3 quarts of water or anti-freeze to fill it.

[scoobaroo]

I have a question. my car recently started doing this. Whenever i'm stopped and not moving or moving at a very slow speed (stop and go traffic, red light, etc), the fans will turn on. If i let the car sit for too long, the coolant temp will gradually rise to the H mark. When i start moving at normal cruising speed again though, the temperature will go back down to normal. I tried replacing the radiator cap because my friend told me my old one wasn't holding pressure right but my car still overheats. The only difference is that the fans will kick on and it will stay at the same temperature until i give the car gas to start moving. When i give it gas, the temp gauge will then move up to H until i start moving again and stay at low revs.

Does anyone know what might be the problem?

[shmshm]

ahh, the coolant system. i recently got rid of my 91' acura legend.. the last few months/weeks that i had it, i saw nothing but fluctuation in the temp. gauge. sometimes i couldn't even slow down to stop at a light without a rise in temp..even with all new hoses, new radiator, etc. (although it was a really great car in all other aspects).
i recently purchased a bone-stock silver 03' 2.5rs and i'm really hoping all these cooling system problems are just cautions, haha. i dont want to have to be staring at my temp. gauge forever, all over again!

[impreza_GC8]

Originally Posted by solbey11

4. A stock radiator cap is designed to only hold 16 PSI of pressure. The STi cap holds around 19 PSI. The extra pressure created by these caps will most likely cause radiator failure when used on a stock cooling system.

So I read that a higher pressure rad cap will cause "failure" if used with a stock cooling system. I've been using a ZeroSports 1.3Bar (18 psi) cap on my N/A RS for nearly a year now with no issues that I can tell. What sort of affect has this cap had on my cooling system?

[kainam00]

^ It can crack the plastic tanks on your radiator... I've had this happen with the STI cap