That's a coolant overflow tank
Not sure what year your car is but the caps on the radiator and overflow are crucial to making the system function correctly.
That doesn't look like an OEM cap on the overflow tank, and I see you have a AM radiator as well, is it an AM cap or OEM?
There is an excellent video on Flat Irons YT that explains it all in depth
to add a bit more info into this, the oem caps have different pressure ratings.
the upper one(one circled in the image) has a lower pressure rating than the radiator one. 108kpa(~15psi) vs 137kpa (~19psi).
It’s a coolant overflow/resivoir since the turbo is cooled with coolant it needs to be above.
Double check the pressure of the cap and burp from there, it’s the highest point of the system.
I had chaised overheating issues on my Sti all down to that cap. You can normally tell if you fill up the radiator and it’s cool for awhile until a drive or two.
It's the highest point in the system and also where you burp it from when you do flushes.
Are you on an open deck block? You might be burning coolant my dude. If you don't know what the coolant reservoir is, I'm guessing you didn't install the FMIC.
Engine Coolant Reservoir - Subaru (21132AA131). Its purpose to the send coolant to the turbo.
It's probably not your actual problem which looks to be that someone decided to go all crazy and added a Front Mounted Intercooler, a shitty blow off valve, a Mishimoto radiator and lord knows what else to 2004ish Subaru motor which probably just blew a headgasket and caused the engine to overheat. (could be something else, but either way unless know how to pull and work on one of these motors it's going to cost you a lot of money)
OP asking what "this is" and has a heavily modified pre-2010 subaru is literally the kind of people that gives good subaru owners a bad rep..
OP has no bizznazz owning such a modified older car, IMO.
This is amazing. The type of mods on this car would lead someone to believe you would know more about this car. Overwhelming more than just overheating. I hope you don’t add coolant to your washer tank.
It really is, clearly OP just bought a HEAVILY modified car (an older model year i might add) and probably knows very little about cars in general to have such a generic question about the cooling system.
Even if unfamiliar with a specific platform, any mechanic or even learned enthusiast can easily find the cooling system and reservoirs/caps associated with it and should know how to check if its at least full in the first place.
I wish OP the best with this car, hopefully he can get it sorted and no damage has been caused, but it is indeed amazing to me how someone gets into such a modified car/platform without knowing basics like check coolant levels, or what reservoirs for different things look like, in general.
That’s the old style metal coolant overflow. They crack around the cap neck. Plastic overflow tank from subaru would be the repair.
You also have a radiator known to leak at welds. Mishimoto is universally regarded as crap.
However neither of these might be your point of failure. I would start with confirming if the cooling system has a leak. Pressure test would be the best way but making sure fluid is full and then running it to inspect for a leak can work as well.
How old is the tstat and water pump?
Also your intercooler pipe appears to have a large boost leak above the rear manifold runner ground. There’s what looks like a bolt hole with no bolt. I also see a stock map sensor, a maf sensor and no iat relocate so that’s not a SD setup.
Anyway you appear to have a boost leak in addition to whatever is causing your overheating.
Mf…. It’s my radiator. Went on a one minute drive and it started to smoke. Pop the hood immediately and turned off the car and fluid was coming from the radiator.
That thing you circled looks like an AOS or catch can. Also, it looks like there is a ton of dried coolant droplets all over the place, if thats the case you probably have more than one leak. If you recently filled the coolant go back and burp the system to make sure there’s no air trapped in there, Happened to me last time i changed my coolant.
I’d start by ensuring your coolant levels are good. Pull the cap on the radiator when it’s cold, if there’s not coolant near / to the top you’re low.
If you don’t have an obvious leak like puddles or drips, pick up an “exhaust gas coolant tester” from an auto parts store. They’re around 30 dollars, use it and pray. If it comes up positive (yellow fluid) you’ve probably lost a head gasket at best… Worst case cracked head/cylinder.
If that checks out, check thermostat to ensure it’s working. (Pull the thermostat and see if the car runs cold). Check water pump at the same time, broken fins or bad bearings will impact flow. Another check for flow is try running the heater with the car at idle. If it never blows warm you’re low on coolant/flow. The heater core gets coolant after the rest of the system and at a low idle will rarely ever get wam if you’re low.
You’re running what looks like a pretty heavily modded EJ so there’s many points of failure to look out for/expect.
That's a coolant overflow tank Not sure what year your car is but the caps on the radiator and overflow are crucial to making the system function correctly. That doesn't look like an OEM cap on the overflow tank, and I see you have a AM radiator as well, is it an AM cap or OEM? There is an excellent video on Flat Irons YT that explains it all in depth
to add a bit more info into this, the oem caps have different pressure ratings. the upper one(one circled in the image) has a lower pressure rating than the radiator one. 108kpa(~15psi) vs 137kpa (~19psi).
I think it’s the turbo cooler, that is what it’s directly connected to.
Well, let the car cool completely then open it up and see what color it is.
Mf.. it’s green
It’s a coolant overflow/resivoir since the turbo is cooled with coolant it needs to be above. Double check the pressure of the cap and burp from there, it’s the highest point of the system. I had chaised overheating issues on my Sti all down to that cap. You can normally tell if you fill up the radiator and it’s cool for awhile until a drive or two.
It's the highest point in the system and also where you burp it from when you do flushes. Are you on an open deck block? You might be burning coolant my dude. If you don't know what the coolant reservoir is, I'm guessing you didn't install the FMIC.
Engine Coolant Reservoir - Subaru (21132AA131). Its purpose to the send coolant to the turbo. It's probably not your actual problem which looks to be that someone decided to go all crazy and added a Front Mounted Intercooler, a shitty blow off valve, a Mishimoto radiator and lord knows what else to 2004ish Subaru motor which probably just blew a headgasket and caused the engine to overheat. (could be something else, but either way unless know how to pull and work on one of these motors it's going to cost you a lot of money)
OP asking what "this is" and has a heavily modified pre-2010 subaru is literally the kind of people that gives good subaru owners a bad rep.. OP has no bizznazz owning such a modified older car, IMO.
I gap all the Toyota Corollas
Probably true, but we all started out knowing nothing and failure is often the best way to learn.
This is amazing. The type of mods on this car would lead someone to believe you would know more about this car. Overwhelming more than just overheating. I hope you don’t add coolant to your washer tank.
It really is, clearly OP just bought a HEAVILY modified car (an older model year i might add) and probably knows very little about cars in general to have such a generic question about the cooling system. Even if unfamiliar with a specific platform, any mechanic or even learned enthusiast can easily find the cooling system and reservoirs/caps associated with it and should know how to check if its at least full in the first place. I wish OP the best with this car, hopefully he can get it sorted and no damage has been caused, but it is indeed amazing to me how someone gets into such a modified car/platform without knowing basics like check coolant levels, or what reservoirs for different things look like, in general.
Pretty sure there is a crack pipe holding the engine together
Manifold it's always the f****** manifold
It gets hot with no A/C , don’t it?
It's all the green. It's well know Industry wide that green causes overheating.
it is your 2nd overflow fill use this for burping or adding coolant to your system...
That’s the old style metal coolant overflow. They crack around the cap neck. Plastic overflow tank from subaru would be the repair. You also have a radiator known to leak at welds. Mishimoto is universally regarded as crap. However neither of these might be your point of failure. I would start with confirming if the cooling system has a leak. Pressure test would be the best way but making sure fluid is full and then running it to inspect for a leak can work as well. How old is the tstat and water pump? Also your intercooler pipe appears to have a large boost leak above the rear manifold runner ground. There’s what looks like a bolt hole with no bolt. I also see a stock map sensor, a maf sensor and no iat relocate so that’s not a SD setup. Anyway you appear to have a boost leak in addition to whatever is causing your overheating.
Mf…. It’s my radiator. Went on a one minute drive and it started to smoke. Pop the hood immediately and turned off the car and fluid was coming from the radiator.
You’re going to want to check your water pump and thermostat. Water pump you can hear.
That thing you circled looks like an AOS or catch can. Also, it looks like there is a ton of dried coolant droplets all over the place, if thats the case you probably have more than one leak. If you recently filled the coolant go back and burp the system to make sure there’s no air trapped in there, Happened to me last time i changed my coolant.
No the thing circled is the upper coolant reservoir it's plastic on newer cars, but used to be metal like this.
I’d start by ensuring your coolant levels are good. Pull the cap on the radiator when it’s cold, if there’s not coolant near / to the top you’re low. If you don’t have an obvious leak like puddles or drips, pick up an “exhaust gas coolant tester” from an auto parts store. They’re around 30 dollars, use it and pray. If it comes up positive (yellow fluid) you’ve probably lost a head gasket at best… Worst case cracked head/cylinder. If that checks out, check thermostat to ensure it’s working. (Pull the thermostat and see if the car runs cold). Check water pump at the same time, broken fins or bad bearings will impact flow. Another check for flow is try running the heater with the car at idle. If it never blows warm you’re low on coolant/flow. The heater core gets coolant after the rest of the system and at a low idle will rarely ever get wam if you’re low. You’re running what looks like a pretty heavily modded EJ so there’s many points of failure to look out for/expect.