Wanted to have a quick intro, always wanted a evo. Finally got an evo. But its been about three years since i've had it, and its semi driving right.

Long story short, I bought a 03 evo that was built by Pure Tuning in Ohio. The car never ran correctly, and it has been a lot of back and forth over the three years, and now I'm down to my final issue. Coolant temps. The car is a built 2.0 and originally had a half radiator with a spal fan (now with full size koyo radiator, still same issue). Every 2-3-4 gear pull, i'd see a huge spike in coolant temps. At one point, it spiked to over 220... verified with defi gauge, and a new coolant temp sensor. The shop used dex cool as a coolant... had dsm/evo car friends tell me to get rid of that and run distilled water with water wetter or oem. Went with distilled and water wetter for now and the issue is not as bad. But still climbs to about 200 based on the gauge.

What could cause such issue? I know head gasket is good (verified by block test, and coolant pressure test), thermostat is new, fans kick on, I'm kind of at a lost. I dont believe an air pocket is in the system since ive bled the system. Any advice on actual coolant temps would be helpful. Thanks for your time. PFA.

 

Nice pic BTW @vinny.dtw Looks clean & like the look

Cant help too much w/your issue but you noted the engine had the 1/2 radiator which indicates a fwd facing turbo for a drag set-up. They didnt fill or 1/2 fill the block by chance?
I run gauges but not for water temp & my needle gauge always hovers at below the mid-point i think

The other guys will likely have a better feel for your issue

Cheers, Joe

 

Thanks for the compliments.

I don't have a forward face setup. Just a full race tubular manifold with a gen gtx3582.

Currently running a full size koyo radiator and the spal fan.

 

where is your sensor mounted?

block filled? (as asked before)

 

Block is not filled, and the sensor is right at the thermostat housing. I believe the rear one goes to my defi gauge, and the front goes to the ecu.

 

Dexcool has no place in the Evo’s coolant system.

When’s the last time the water pump was replaced?

Is the car losing any coolant at all?

Never had an issue with the cooling system on any Evo , hell in my personal car I didn’t even run an inner fan for years and over 40k miles and still the car wouldn’t even get to 200* even after hours of bumper to bumper traffic.

I would start with a complete flush of the coolant system, trying to get as much coolant out as physically possible from the system idle it with the lower rad hose disconnected, trying to get the most out of the block as you can before buttoning it back up.

I’d then refill the system with your flavor of Ethylene Glycol based pre-mix green coolant, Or the safe for any car Penszoil Yellow coolant I also ran for years, AMSOIL also makes a great coolant. Dependent on your climate you may be able to go 60/40 or 70/30 mix of water to Antifreeze. Then add a bottle of Redline Water Wetter, or any of the other ones Royal Purple, AMSOIL, and a couple other companies make them.

Fill the Rad and Overflow bottle and let it run w/ Rad cap off filling the car as coolant level drops, I like to give the radiator hoses some squeezing during the process, put your heater on full blast and recirculate I run it through all positions too from feet to defrost and back. Run it until the fans cycle 3 times and make sure you have heat. Top off if needed. Drive the car and monitor coolant temps, if issues continue I’d replace the Water Pump depending on age, after that there could be an issue with the coolant passage/s in the built motor.




Another thought which isn’t an issue I’ve ever seen in any Evo with the known bolt on intercoolers on the market, however if you have some crazy custom FMIC set up it could be blocking flow to the radiator. Also do you run an under drive pulley on the water pump? If so get it off there,

Best of luck resolving the issue. This should enable you to pin point the issue a tree sss