MitsuStyle - Head Games: pushing coolant and then...

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Head Games: pushing coolant and then...

So first off I must say that my evo has been the most reliable turbo awd mitsubishi I've ever owned. And the most powerful...not insane power, but 300+whp for daily use is just endless fun.

About 3 weeks ago I pulled into my work parking lot and the temp gauge went way high, almost to gauge max. It quickly went back down, but I could not help but wonder wtf the deal was! I got home and discovered that the coolant was low. The car was just rolling over 60k miles, and I had plans to do the timing belt with the water pump anyways, so I ordered all the parts and decided to get that out of the way before I jumped to too many conclusions. I found a TSB for 05 Evos regarding premature water pump failure, so this just backed up me doing the water pump sooner than later.

After some leaky water pump issues, I got the car running good and not loosing any coolant with gentle driving and light boost. I had turned down the boost, timing, and richened up the tune to keep things gentle on the car. After some WOT testing, I suspected coolant being lost still but thought maybe I had overfilled it, had air bubbles, blah blah blah, I made lots of excuses to tear my mind away from the obvious.

I did a compression test: 182 175 180 175.

I changed the thermostat. I changed the radiator cap. Still, no matter what I've done, if I boost the car, coolant finds its way out of the overflow bottle. The cap even blew off a few times, but it turns out I had accidently folded the rubber seal over a bit on the cap, which I think led to this.

I turned the boost back up. The car rips as normal, full power is about 380whp (dyno dynamics) on my E85 tune and the car drives perfectly. However, when I park the car and let it cool, coolant is low....obviously low. Probably filled it with about a 20 oz bottle several times. So, I turned the boost back down.

I did a leak-down test. Not really looking for results form the gauge, just mostly looking for bubbles or movement in the coolant. I'm guessing the 100psi (gauge max) I put on the cylinder is not enough to simulate cylinder pressure under boost, as I saw nothing.

I talked to shane @ DB through all of this, and he was very helpful in giving me ideas of stuff to try, but in the end he advised that when cars have symptoms like this that are not diagnosable with regular tests, that a headgasket or warped head are to blame.

The car has overheated a few times. At about 25k miles, 2 years ago, I blew out the freeze plug from the water pump, which promptly pumped out all of the coolant. I got the car over to the side of the road fairly quickly, found the freeze plug and tapped it back in, and drove it ever since. I had Shane @ DB install a set of arp head studs 1x1 method when he was putting in my cams.

Also, last winter my crank pulley got ripped off by a chunk of ice on the freeway. I tried to limp the car back to my house, but realized shortly therafter that the acc belt ran the water pump. The car got a little hot then too.

So anyways, just looking for feedback, anyone with any ideas of what I could try before pulling the head off. I have some other plans, but I'll fill you in on those later.