ShanesEVO

I was at Streets of Willow for a track day yesterday and on my last lap my water temp gauge went pretty high, then when i turned on the heater it went down and proceeded to go back up. Coolant overflow was nearly to the top of the bottle. Drove the car home, no overheating issues what so ever. I get up to do some testing this morning and the overflow is totally dry. Refilled overflow and checked rad looked low so i refilled the radiator. Did a compression test 145-150-150-145 all looked good.
any imputs are welcome
Thanks

barneyb

Sounds like the head lifted.

ShanesEVO

what in my description made you think that?

barneyb

I've been on one forum or another supporting 4g63 powered cars since 1992. With this engine a blown headgasket almost always results in combustion gases going to the water jacket, combustion gases fill the engine and coolant goes to and overflows the reservoir. I'm sure there are exceptions but they are rare. Once off high boost, the head, unless badly warped, reseals. This makes diagnosis difficult. Your description of events matches the above scenario.

I'd certainly try a thermostat first and then beat on it again to see if the problem reoccurs.

CurseDSM

iTrader: (3)

+1 to that. Just check your oil. If your oil is milky yep head gasket, if not then t stat. I know when my talon hg was blown no matter what i did it pushed coolant in the overflow and all over the place.

CaptainSquirts

iTrader: (3)

Check your ground on the intake manifold that bolts right under the strut tower/firewall area.. My Coolant gauge on the dashboard would randomly rise to hot. I noticed the ground that goes from intake manifold to under strut tower/firewall area snapped/ripped apart. Replaced the ground and issue never came back. Easy quick check.

ShanesEVO

not milky what so ever. oil looks brand new and no white smoke out of the tail pipe

ShanesEVO

checking right now!

barneyb

Another means of checking for a bad manifold ground is to monitor the coolant temperature reported by the ECU. The ECU uses a different sensor, one not affected by a bad manifold ground. So, when the dash temp gauge reads high and the ECU temperature is normal, it is a grounding problem.

WickedRSEvo

iTrader: (7)

I have this exact same issue right now. I just replaced the thermostat today, and refilled coolant. I then took it out for a couple pulls. The temp did not rise above the middle of the gauge, but my coolant overflow was almost full when I got back. Is that normal, or am I looking at a headgasket in my near future? Compression is 150 across the board. Oil isn't milky. Car pulls hard, and was just tuned on dual maps in March. The craziest thing about it, is that it only occurs when on e85. When I'm on my 93 map, almost no coolant is in the overflow. Not to thread jack, but it's pretty much the same deal. Thoughts?

ShanesEVO

i also was on e85 when this happened

ShanesEVO

can you possibly post a picture? i only saw the black wire that connected to the strut tower brace itself

barneyb

I'm the last person to ask about tuning but maybe your E85 tune is a little too aggressive. Perhaps post in the E85 tuning section in hopes of getting good advice there.

CaptainSquirts

iTrader: (3)

Aby@MIL.SPEC

iTrader: (161)

sounds like headgasket to me.

pump vs e85, generally means more boost & timing on e85 = higher cylinder pressure when firing.

150psi during compression test vs 2600 - 2900psi when firing (180-200 bar cylinder pressure)

If your actually knocking, then that cylinder pressure not only goes up (20/40 bar spikes = 280/600 psi more), but the rate @ which the spike rises fck's you too.

so yeah, depending how bad the issue is, it may only manifest while on e85 & high boost or simply idling = your HG is FCKD.