I tried searching but did not find anything specific to the issue I had over the weekend. I attended a local autocross club's member's only event. Since it was members only we were able to make quite a few back to back runs (I averaged 47 seconds a run). Anyways, I changed my coolant approximately 2,000 miles ago or around 6 months ado. When I did the coolant change I refilled with 30% coolant and 70% distilled water with a bottle of redline water wetter to boot. Well after about 5-6 consecutive runs I went and parked my car. Before shutting down it idled for maybe 30-45 seconds. I pop my hood to let the car cool and I notice two things: 1) there is a sheen around my power steering fluid reservoir and it looks like some bubbled out the top of the cap.
2) I can hear a bubbling kind of noise coming from the radiator/manifold area.

I go back to the car and turn the key and the water temp gauge pegs to hot. My OEM oil temp gauge read in the middle. I freaked out and turned the car on with heater at full blast and the water temp eventually fell to the middle. I turned the car off and let it cool down. I drove home about 40 mins and did not notice the water temp gauge rise at all. Was this a fluke? The back to back runs overheated my coolant system? Thoughts?

Thanks

 

Stock or Aftermarket rad?

something similar happened to me, i was on track for a 20 mins session parked the car after that, then came back in 15 mins to find my car pissed a good amount of coolant

i let it sit for 40 mins, drove it back home (2hr) logged everything... all parameters WNL

 

That's normal. Same happened to me first time I went to an event like that. Just let the car idle for a few minutes before shutting off. I eventually got a mishimoto radiator and air diversion plate.

 

Stock radiator. I just checked my reservoir and found brown sludge most people who use redline water wetter report.

 

So nothing to be worried about for now? Just make site let the car idle a bit before shutting down next time? I have a turbo timer but I usually just leave it set at 30 secs

 

probably it would be a good idea to drive around before parking like a cool down lap.

 

I would change your fluid and this time leave out the Coolant Additive.

 

hate to say it but sounds to me like you have a blown headgasket.

 

I think the brown sludge was due to water wetter. Haven't had a chance to run the at hard again similar to autos circumstances but I have done driving around in the heat and it's been ok so far.