really not sure where to post this, if it needs to be moved thats fine

2006 wrx wagon. vf39, 05 STI drivetrain swap.... plus much more of course

having major overheating issues on the track. Only able to run like 1-1.5 laps before the needle just soars to the red. I have upgraded to the mishimoto radiator and am running my heater already. thermostat has been drilled out, both caps are 1.3bar. I have a splitter/undertray on that extends back behind the oil pan, and I have the greddy air panel diffuser thing on the top that connects the bumper to the radiator. Running probably 1/4 dexcool, 3/4 water/water wetter. fans work as well. removed the grilles and took off my hella supertones to try and get even more air in.

really not sure what could be wrong still. Only runs hot on the track, not on the street. The A/C condensor is pretty ****ed up on the bottom half, but because i have air being forced through from the top and bottom, i dont see how it could be the problem still. Also because I really opened up the top half to air (which looks fine) it doesnt make sense.

what soultions should I be looking at here? any help is appreciated

 

could be head gasket, (not that I wish that on anyone) but having worked on several overheating subarus I know how fickle the gaskets can be. it might just take a couple G's to get the air bubble to fall into a place where it prevents flow. Nice thing is the heads are short and don't often warp.. although the single overhead cam engines tend to be better.

check for telltale signs air bubbles in the coolant, or disappearing coolant, white smoke, they don't often milk up the oil or vice versa. it's usually between the water jacket and cylinder. but without pressurizing the cooling system it's going to be hard to diagnose.

I've seen 2.5, 2.0, and 2.2 motors all shit the gaskets.. and more often then not the overheating is intermittent. I thought the STI semi closed deck was supposed to be better, but who knows.

 

Are you certain your system is bled completely and free of air? Some systems have high points that like to trap air and make bleeding a pain. An air separator tank setup can be nice to make sure and they're pretty cheap on ebay.

Hate to go there on such a new setup, but what about the headgasket? If it's only doing it at the track maybe you have a head gasket sealing problem under boost/wot. Maybe try one of those hydrocarbon test strips.

*edit /\/\ beat me to the punch, haha.

 

Edit, I was going to agree with air in the system but if it doesn't overheat on the street I find that hard to believe too.

IIRC correct fill procedure for the suby is filling from the highest opening to the coolant system over on the turbo side....... heater on/fan on high is prob a good idea too

 

are you front mount or top mount still?

 

Something is broken or you have air in your system (but as Charles said, in that case you would see it on the street too).

I run a FMIC, undrilled thermostat, and have no cooling/diverter panels added on. I ran at Sebring for 4 20-minute sessions in 90F heat.

My experience with EJ2x headgaskets does not match that of treekiller's at all. Head gasket problems, from all I can tell in the last 9 years of reading forums daily, are very rare on our engines. Most engine builders and tuners alike will recommend the stock headgasket even to 500HP. Who knows though...

 

What rpm are you shifting and what is redline?

 

Jblane: I'm not sure if it's related at all to Location (e.g. weather or temp).. but the OLD EJ25 DOHC 1997-1998 was a horror show. you could set your watch by the headgaskets going at 60,000-70,000 miles. (From my communication with some rally guys apparently even JDM cars of that vintage were the same) The SOHC EJ25 solved most, if not all of those issues, but I have seen 2 so far early (02-03) 2.0 wrx DOHC motors let go too, one just in June at a rallycross.. some early 2.2 turbo kitted cars I did were hard on gaskets too.

and I personally cooked a loaned early 2.5RS during a rally. funny thing is 4 years later that same exact 2.5RS came into my shop for another engine, which we thankfully had in stock, and rebuilt with the then "new" gaskets

you are right I thought the multi-peice coated gaskets were the holy grail in solving that problem, but apparently subaru felt it required to beef up the the 2.5 turbo cars. I thought this was in direct response to more Headgasket issues, but I have been VERY removed from any subaru work for nearly 6 years, so please take it with a grain of salt. I've never turned a wrench on a USDM STi engine so I cannot comment with 100% confidence, Now give me an EA82t and we can talk

 

You thinking cavitation at high rpm Chuck ? or is that still even an issue with modern water pumps/cooling systems?

 

Nope, the heat. A few hundred rpms can make a big difference in maintaining reasonable temps. There really is no need to run every lap like it's a qualifying lap, the pros don't, why should an amatuer?

I don't know anything about the Mishimoto Radiator but if it doesn't have a larger capacity than stock it really isn't much of an upgrade.

He says the thermostat has been drilled out but he doesn't give details. If it's just a 1/4-hole so the air can escape then it shouldn't be a problem, but if the whole thermo is gone then that is his problem. The water is moving too fast through the engine and not spending enough time in the radiator to cool down.

If none of the above applies then I would look at the underbelly. It could be holding up airflow in the engine bay.