FOSS

I drove to Sonoma yesterday, it was quite hot outside - high ~90. My S2K started to overheat. The coolant level was fine. I could drop the temperature with AC off and the heater all the way up but as soon as I turned it off and turned AC on it started to overheat again.

Then I drove to the coast and when outside temperature dropped to high 70s the car stopped overheating.

I had a similar problem 3-4 weeks ago but when I checked the coolant level - it was completely out. I thought it was a water pump so I took my car to the mechanic and after checking it he said a radiator cap spring was broken. He changed the cap but I never really drove in that hot weather for the last 3 weeks until yesterday.

My other thought is - maybe it's a thermostat?

Does anybody of you guys know what could be a problem?

My S2000 is 2006 with 115k miles, all stock.

zeroptzero

You almost definitely have air in the system if the coolant overflow tank was allowed to empty, that will almost always cause overheating.

It's really hard to overheat these cars if all of the systems are operating normally - no air in the system, rad fans operate properly, and the thermostat is functioning. I've had mine in 106+ F degree conditions with no difference in coolant temps.

Check that the fans come on , and burp the cooling system of any air pockets. If it still occurs after that then I would suspect the thermostat as the last culprit.

FOSS

I've checked fans - they were fine. Few years ago I drove in ~110 temperature by Clear Lake here in California and it was fine too. These few times were the only times my temperature jumped up from normal.

You are right - it might be the air in the system as overflow tank was completely empty when my coolant was out.

zeroptzero

The coolant tank isn't air tight, so the engine cooling system will draw in air once the coolant tank empties. You should do a bleed procedure, and it will likely take 2-3 attempts to get all of the air out as it gets stubborn once you drive around with air in the system. Search Billman250's recommended procedure DIY.

FOSS

Thanks a lot, I'll check it out.

FOSS

So I took my car to mechanic and after bleeding procedure, he said bubbles were coming up so his conclusion was - a head gasket.

He is a good mechanic but I'm not sure if to believe it or not. I don't have white smoke coming out from my exhaust, my oil is fine, only thing I've been noticing it was overheating when it's hot outside and some loss of coolant.

I've got a quote - $2,700 including parts, 8-9 hour labor and timing chain. It seems very high to me, especially if the problem is not a head gasket.

Could any of you guys share what did you pay for the head gasket parts + labor? Also could you recommend any good mechanic for checking if it's really a head gasket around San Francisco?

realblag

Do a chemical test on the coolant to see if combustion gasses are present. If he was a good mechanic, he would have done this.

jkelley

Your mechanic does not know this car. Timing chain? No. That's dumb.

My suggestion is you take your car to Jordanksartell in TN or Billman250 in NY if you are close to either. Many people drive hundreds of miles to see both of these guys because they are very knowledgeable with this car, specifically. Not to mention I had Jordan replace my head (had a burnt valve) and it cost considerably less than what that guy quoted... and I obviously had to replace the head gasket too lol.

Slowcrash_101

If it is a head gasket and you have some head warping, you will need to mill the head, you can remove the head without removing the engine, or the timing chain, so your mechanic may not know too much about working on these engines or he's trying to stiff you. Milling the head shouldn't cost more than $150, the head gasket is cheaper than that, plus new head bolts, so you can do it considerably cheaper if you do it yourself. All considered it should be about around 6 - 8 hours of labor plus machining, if it was me I would do it for about $750 everything included, that's if your head is within milling spec.

FOSS

Thanks guys for suggestions. It's a pity I live too far away from Billman250 (in California), once he suggested me a fix for a bucket swap which fixed my vibration problem.

This weekend I'm planning to take it to other mechanic for the 2nd opinion.