astral

Hey all.

New Evo 8 owner here.

A little background on my car.
Water pump was done by the previous owner at 110k, the car now has 150k. It was a single owner and owned by the wife of a CHP officer.

So my issue is as follows. A week back I found my car getting hot. Very hot.
The temp increases randomly, it will happen even at low RPM with load load (constant freeway cruising throttle) on the freeway, when I pull up to a light, etc.

Stuff I've replaced:

I replaced the serpentine/accessory belt as I thought that the belt could be slipping and stopping water pump flow.
Did not fix the issue.

I then replaced the thermostat with an OE thermostat. Old one was absolutely completely shot.
I'm still having the issue.

I'm now looking at replacing the rad at this point..

Can anyone give me any insight? Does this simply sound like air in the system?
also, every time i check my coolant when the car is cool, the rad is never filled up to the brim so I add distilled water. The overflow tank is more full than it previously was.
Whenever I open the rad cap, it makes a "tssssss"

Thanks in advance.

Compression test had all 4 cylinders within 5 PSI of each other.

Ferp

Are your rad fans not coming on sometimes? It's something worth checking for. Also a rad upgrade, even if it doesn't solve the problem, is always a good move.

astral

You know, I thought this initially, but that wouldn't explain overheating on the freeway where the fans basically do nothing.

Evo_Goodness

Maybe head gasket if I had to put my finger on it I know on subarus that's the first sign of a head gasket crapping out on them which seems to happen a lot ask me how I know lol

astral

"That's the first sign of a head gasket crapping out"
What sign in particular are you referring to?

I've got no symptoms of head gasket failure, such as tail pipe coolant burn off, frothiness in the oil/coolant reservoirs and caps. As stated in the OP, compression test results are within 5 psi of each other.

barneyb

If the ground wire between the intake manifold and firewall becomes open (time and corrosion will do it) the dash temperature gauge goes nuts. So, that's the first thing I would check. Also, the fix costs zero dollars. Another thing you can do, if you have the equipment, is check the coolant temperature by way of a scanner. The ECU uses a different temperature sensor. If they don't both read hot it is probably a gauge problem.

Beyond that I agree with the above, it sounds like a head gasket failure.

astral

Eh yeah I'm actually starting to suspect head gasket.

I bled the cooling system again today, and there was a **** ton of air in the system. The unfortunate thing was... the air never stopped. Even after an hour of bleeding, the air bubbles wouldn't stop pouring over into my funnel.

RazorLab

iTrader: (8)

Sounds like air in the system. Keep burping it.

astral

I called it a night, but I'll get back to burping it for another hour or two tomorrow, and see how it goes. I'll definitely report back.

Will get a second compression/leakdown test as well as a head gasket test later this week for further diagnosis.

Another bit of information to add is that I am running straight distilled water with redline water wetter.

RazorLab

iTrader: (8)

Yea usually if the temp gauge bounces around like that is because an air pocket hits the temp sensor

astral

Thanks. The thing that confuses me is the fact that I burped/bled the system for about an hour, with lots of idle time, as well as hard revs and heater on and off and the air wouldn't stop coming out. I guess we'll see tomorrow.

barneyb

It seems like I'm always doing something that includes having to drain the radiator. When time to fill I pour the radiator full, idle the engine, the coolant gradually climbs up the fill funnel until suddenly it is gone. The thermostat has opened allowing the air to come out. At that point I fill and cap. Done. There is no air remaining in the cooling system. Bubbling for an hour is not normal.

astral

So I'm guessing you're in the "it's the head gasket" camp here?

Evo_Goodness

Is the side tank reservoir bubbling that's a good sign of head gasket failure just because the compression check was all within 5 psi doesn't mean that the head gasket isn't failing

Tekniq

iTrader: (11)

Post 30 maybe?

https://www.evolutionm.net/forums/ev...r-boost-2.html

Part #1308A012