Overheat/Won't cool down efficiently issue - Long post/videos

[booki]

Hey all, I have a MY09 subaru forester xt, 5 speed man.

 

The car has had a heap of new parts (will be detailed in a list), and now the car is somewhat overheating. I have been monitoring my cars coolant temps via a obd2 gauge and have noticed the following concerning scenario's (keep in mind, it is our winter at the moment with temps ranging 10c on average).

While the car is idling stationary the cars temps will get up to 95c, fans will kick on, bring the temp down to 94c and the fans will stay on indefinitly. Fans are working correctly - just the car isn't cooling down. Normally I would expect the fans to kick on, and the temps to start coming down to maybe the high 80's.

 

While driving, specifically just at light load/cruise - the cars temps will climb, as long as my foot is on the accelerator pedal they continue to rise. i have had them as hot as 99c, I would imagine it would just keep getting hotter if I was on a long freeway drive, but I don't want to do any damage to the motor as its all new. Also these are just straight roads (not hilly or anything strenuous), but as soon as I let go of the accelerator the temps will come down , but still hover in the low 90c range then just slowly creep back up. Something isn't right...

 

Normal temps to my understanding are generally around the 82c-91c range. This would be in all conditions, from light cruise to heavy traffic. General rule of thumb here. Thats the response's I have gotten from other owners of the same car in my climate.

 

Now the things that are worth noting;
Brand New EJ257 Shortblock
Reco Heads
ARP Head studs
VF52 Turbo, TBE, 3port
OEM Head Gaskets Used
Brand new Mishimoto Radiator
Waterpump replaced during shortblock install - Mizumo Auto Kit (Mishiboshi belt, gmb pump and tensioners)
New Hoses everywhere
New Thermostat

Troubleshooting I have done - everything listed here has made no effect on temps;
Tried running with no thermostat - no difference
Tried bypassing heatcore -  no difference
Tried two different radiators  - no difference
Tried a new thermostat -  no difference
Replaced Temp Sensor - no difference
Ran water through the thermostat housing, seemed to flow through fine
Bleed the system, Even had a shop bleed the system prior the dyno tune -  no difference
The shop commented on the temps being unusual compared to there "norm" Subaru EJ tunes 


The only thing I have not replaced is the water pump during this troubleshooting - being as it was brand new during the shortblock replacement....but maybe the GMB pumps are not up to the task compared to OEM water pumps?

See some Videos here;
https://www.youtube.com/playlist?list=PLqe9onC8cv6aPvbzUwN_p8VKiEKH0Oswj


Sorry for the long post, but the car is currently apart and I have a new genuine water pump to put in it - I have noticed some difference's between the GMB pump and the Genuine pump, but they are minor and I wouldn't think would cause a poor flow issue....but I guess time will tell once I put the genuine pump in.

[golucky66]

In my experience on a 2004 and 2006 Baja Turbo (same engine basically) they run around 197 F cruising. And upwards of 212-214 stationary until fans kick on and bring the temperature back.

 

While 100 C might sound scary because water boils at 100 C. Remember it's coolant, so the boiling point is already higher naturally. And the pressure in the system (~ 16 psi) raises the boiling point even more.

Now would 230+ F start to worry me, oh heck yeah. But cruising at 95 C (203 F) i wouldn't worry too much personally.

As for why the fans come on at 95 C, I'm not to sure. 

What brand thermostat are you running? It needs to be an OEM or OEM style. Most aftermarkets don't open properly on these cars. And what temperature is it rated to open at?

Edited August 3, 2018 by golucky66

[booki]

I am chasing those temps you have seen. They seem normal to me.

 

Fans on at 95c is the default ecu program. They should bring the temps down rapidly... though they don't.

 

I am using a OEM thermostat and will be replacing it just to be sure when I change the pump. The stat is rated at 78c from memory. And is fully open by 92c.