overheated.....GN1 heads.....strange stuff...should i be worried???

[turbonut85]

Ok....so here goes: Drove the car 3-1/2 hrs to car show with the ac on full...(93* outside) no problems as temps were right around 185-190 the entire way..although I saw a couple of bubbles go into the overflow bottle when I stopped for fuel...thought that was a bit strange, but the temp was fine at 185*. Later that day, (in the heat of the afternoon) we take the car out to a stretch of highway and start beating on it....(we were watching the SM for KNR and o2's...not temp ). So we get back to my buddy's place and park it....dayum was it hot under the hood....so I keyed it on (after it sat and heat soaked for a good 5 min) and the coolant on the SM read 252*! Figured out that with the ac running for 3-1/2 hours, it kept the dual fans on for the same period of time and cooked the chincy cheap ass caspers fan relay in the harness (hot air car converted to dual fans with the F body radiator) so the fans quit.....while we were beating on the car. Replaced and rewired the relay and harness and let the car cool until the next day. Checked the coolant level , and topped it off....drove the car without the ac that day, in town, never saw a temp above 173*, and the car ran fine...and the coolant level in the overflow tank was steady so it didn't seem to be using coolant.
The next day, we headed for home. (another 3-1/2 hr trip) monitored the temp VREY closely all the way home...it ran between 175* and 180* with no ac. Due to my wife's horrible allergies, I reluctantly turned the ac on after about 45 minutes...saw temp hit 190* one time and then it hovered around 185* for the rest of the trip. A couple of miles out from home, I turned the ac off and the temp dropped to 176* and held there all the way. Parked it, and there it sat for several hours. Went out later and pulled the rad cap...(room temp) and coolant(room temp coolant) puked out of the rad...WTH? Let it sit for a couple of days...started it with the rad cap off and all seemed to be fine, however when the t stat opened, I saw bubbles coming up from the bottom of the rad... Then they seemed to dissipate and pretty much went away...? Also, when the t stat opened...the coolant level in the rad dropped to about 2/3 full. Temp climbed to 167*, fans kicked on and pulled it down to 163* within 30 seconds...did this for a good 20 minutes with no problems. A few days later I go back out, start the car, brought it up to temp (rad cap off) then I topped the coolant off and saw more bubbles....then they went away again...? WTF?
The car runs fine....no miss..no smoke...oil is perfectly clear....plugs seem normal (light tan to white...car runs on 100% E-85)...exhaust smells normal (smells of corn) and I can boost the car and the around town temps are 170-176.....SHOULD I BE WORRIED?? The bubbles I see in the rad are the main concern....?? How much heat can the GN1 alum heads take? Got a lot of time and $$$ riding on this build.....hoping all is well...?? Any thoughts are appreciated. TIA!!!

 

[charlief1]

With the water not flowing and no air over the radiator the temps are going to go up Keith. That's just normal. I doubt you over heated it. If you did you would've had other issues when you were trying to drive it home.

 

[BEATAV8]

Seems to be holding pressure but the bubbles would concern me.

I would pressure test it with a cooling system pressurizer and see how it holds pressure over a period of a few hours.

If OK, then top it off and keep driving and monitoring it.

 

[salvageV6]

Water can and does bubble back into the overflow when very hot, I think that's why it's there.

In the radiator I dunno about those....

I hit 245 when the thermostat stuck frozen on me, but it was -4 degrees outside so perhaps that helped.

Keep checking the oil and water for a few days but I doubt you have a problem.

Some builders put heat tabs. on the back of the motor or heads I'd look for those and see if they are melted.