Overheated on track

infernosg · \r\n \r\n \r\n 05-02-2011, 08:02 PM\r\n \r\n \r\n

Overheated the car at Mid-Ohio during HPDE. 7th run of the weekend, 3rd of the day; ambient temperatures around 80F. Coming out of the esses (medium-speed, hard right turn, slightly uphill) in 3rd gear around 5000 RPM the low coolant buzzer went off and the temperature gauge started climbing. Let off and limped into the pits with the heater blasting but the gauge still got to "H". Spent no more than 5 minutes at that condition and did not exceed 3000 RPM during that time. Shut down and there was coolant boiling and steaming out of the overflow bottle. Once cooled off added water to the radiator - didn't take too much initially but the low coolant buzzer kept going off so kept bleeding the system and adding more water. Made the 2.5 hour drive home with no overheating issues but at lower speeds and/or tighter corners the low coolant buzzer would sound and then go off after a while. Added more water last night and drove the car to work today with no buzzer or overheating.

Some observations from before/after:
-Cooling system was flushed June 2010. 60/40 distilled water/anti-freeze mixture with a touch of Redline Water Wetter.
-Since Friday night there's been a high-pitched squealing only during low-speed deceleration. Sounds like belt squeal but goes away as soon as the clutch is pushed in or I get back on the gas. The "adjuster bolt" on the airpump sheared off so it is being held in place by the "lock bolt". Belt seems tight.
-Prior to the run was more coolant in the overflow bottle than usual.
-Prior to the run I had a hard time starting the car. Did the flooded engine start procedure and it limped to life with a little backfiring but idle was steady once warmed up.
-I changed my shifting plan that session - I only went into 4th at one point on the track, rather than three. Engine speeds were almost always above 5000 RPM, but never exceeding 7500 RPM.
-This morning it started a little harder than usual and the engine sounds a little "different" during decel. If in neutral and revved it almost sounds like a 'hissing" noise as engine speed drops but it goes away when it hits idle speed.
-No white smoke, no power loss or any other driveability issues that I can discern.

I know I need to flush and fill the system again - need to get the tap water out of there. Next will be an attempt to replace the sheared adjuster bolt in the airpump and then replace all the belts, but then what? Inspect/replace thermostat? Waterpump? Why did the low coolant buzzer keep coming on and going off? Most importantly, is the engine fried?

For the people who track their FC's is this a result of water pump cavitation? Time for an underdrive pulley of some sort? Time to upgrade the radiator?

\r\n \r\n \r\n 04-11-2011, 09:42 AM\r\n \r\n \r\n	\r\n \r\n #2\r\n \r\n
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\r\n \r\n \r\n 04-21-2011, 02:44 PM\r\n \r\n \r\n	\r\n \r\n #17\r\n \r\n
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