View Full Version : eg33 swap overheating

07-20-2014, 12:03 AM
So I swapped my impreza with an eg33. the eg33 is using the griffin radiator and a morosso inline coolant cap with 20lb cap. Using twin 7 inch fans. So if i drive the car itll get to 220-230 very fast. heres what i've done so far and still cant figure it out.

-Burp the system many times
-new thermostat, run no thermostat
-pull water pump to make sure all is good
-coolant compression test, holding pressure just fine at 15lbs
-no signs of white smoke or coolant/oil mixing
- using temp gun measure temps and the block is indeed spot on with my aftermarket coolant gauge.

the car will idle to about 195/200 but the second i start driving it gets up to 220/230. Anyone have some advice?

07-20-2014, 02:58 AM
You do have all the bypass lines connected correctly? If you run w/o thermostat this is probably not the problem, though.

Sounds more like an airflow issue... 7" fans, especially I you have no shrouds may not be enough.

Is the rad bottom / hose hot or cool?

How do you control the fans?

Have you sealed the rad to the body to prevent airflow leaks?


07-20-2014, 09:50 AM
Why do you think you need a twenty pound cap?
I would try using a block checker to make sure the higher combustion pressures under load aren't escaping into the cooling system. Or if u have pressure tester get it w arm and power brake it and watch the pressure. If pressure jumps you found your problem. Airflow is not usually an issue when moving, fans are mostly for slow speeds and sitting.

07-20-2014, 10:50 AM
If I start driving the car from idle 195, I'll drive to 35 and not come to any stops and itll just climb to 220 then slowly 230, I have tons of open airlfow to the radiator. I have these two dmall fans mounted offset and its really the biggest I can go on a small radiator core like I have and the fans not hit my crank pulley. I could run a 12" in the middle and cut my crank pulley in half, but I'm dealing with overheating while not even at low speeds.. I have the Cometic headgaskets with copper spray on them. I could use a smaller cap but would that really keep it from overheating?

07-20-2014, 11:31 AM
Measure the rad outlet temp. This will eliminate the possibility of it not being able to release the heat to air for any reason.

The svx cooling system operates with a high flow rate and low delta T.

Also, the fans are controlled by engine outlet temp rather than rad bottom temp.

You have experimented running w/o thermostat - should be no restrictions in the flow.

My bet is that the rad is not able to release the heat. Too small or lack of air flow. The airflow across the rad on the svx is low without the fans on - at speed too.

Have you blanked off all other openings so that the total flow actually goes thru the rad?

Anyway, measuring the bottom temp is the easiest thing to do to get forward.


07-20-2014, 08:28 PM
So here's what I did:

Hooked up my radiator compression tester to my coolant system reservoir nipple, leaving my cap in a release pressure setting I am able to view coolant pressure real time while engine runs, started with a cold engine and ran it to 180f. Upon startup 11 psi had come pretty quick with normal idle, then I began to rev it and get it up and by the time I hit 180f I was 22psi... each time I revved the engine a little more pressure was increasing. Despite no oil/coolant mix and no white smoke, I'm thinking this is bad headgaskets and cylinder leakage.

07-20-2014, 08:57 PM
I'm thinking this is bad headgaskets and cylinder leakage.

Do the gas test for the cooling system to verify. Cheap and easy.

If your reservoir does not bubble or you do not loose coolant then how could this be the reason for the high temps you are seeing?


07-20-2014, 10:52 PM
Coolant does boil out of my reservoir.. I thought it was just high temp since I wasn't looking at the overflow until I had reached 220, its not a clear reservoir and it boils out the reservoir

07-20-2014, 11:11 PM

Still, it's real easy to see if it's steam (boiling) or combustion gases (leaking HG) with a kit....

Mine leaked only under high loads.

See the photo.


07-21-2014, 06:32 PM
Fluid went from blue to yellow as a banana. Thanks guys for pointing me in good direction, now I'm on my way to pull engine for headgaskets.. :(