OK so I just hit 75k miles or so... I've never really had any issues with my S2k short of me blowing the rear end at the track a few years ago and it has run great since. On the way home from work Friday about 5 mins into the drive on the highway I look down at my thermostat and it's pegged in the Red... like 5 yellow bars and then 1 red one... I have never seen anything higher then 3 bars so I quickly pulled over to the side of the road and let it cool down for 15 minutes or so... at that point it was back around 3 bars... and I drove it the next 30 mins home with 0 issues at all... it stayed right at 3 bars and operated like normal. Well now today I hop in the car and get ready to take it somewhere... and as I'm pulling out of the driveway I notice it's revving a little higher then usual... then it decided to Rev itself... from about 2000 rpm to 3500 rpm or so over and over for like 10 seconds... at that point I shut her off and wait a few mins... turn it back on and it ran fine to my destination... what in the hell is going on with my car? Any idea's other then it's possessed? It sounds to me like it's electical... like maybe the ecu going out or something since it does control both temp and revving... Note I do have a VAFC and have had it on the car now for about 6 years. Would welcome any input.

 

Might want to check that you dont have a air bubble in the coolant lines.

 

check overflow tank for more coolant than usual. Also, check level of coolant in radiator by opening the cap when cold. Running all 5 bars with a stock ecu is pretty bad. I would be conscerned that there was some form of head warpage etc...

Get in the car as usual, and immediately drive the car. If the coolant level starts rising past 3 bars, immediately pull over and look at the overflow tank, if its bubbling or overflowing, you have a problem. Also feel the bottom radiator tube coming from the radiator. If there it is still cold, yet the top one is hot and the overflow tank is overflowing, you have a problem, either you need to try and bleed the system (which wouldnt make sense as it hasn't been changed in a while), or you have a blown headgasket/warped head/cracked block.

 

the revving kinda worries me towards a warped head or some kind of other damage to the motor, but i dont want to jump to conclusions.

 

let us know what you find out...

 

Bleed the air out of the cooling system. Take off the radiator cap cold and start up the car and keep filling it with coolant to the top and watch for bubbles to come out. Keep waiting for the car to finally warm up and as soon as the thermostat opens pour in more coolant and just keep waiting for the bubbles to stop and then you're good.

 

OK here is an update. First off I took the cap off and saw no bubbles... the radiator was only down about 1-2 cups of water until it was more then overflowing. I have now driven the car to and from work and all around town... (I drive 100-200 miles a day for work) and have had 0 issues with the S2000... no fourth bar of temp... no automatic revving... so I'm really confused. She feels just as strong as before ... took her through VTEC once and seemed fine... so at this point I'm hoping it was just some really strange fluke. At the same time... I have 75k miles on my car and all I've ever done is changed the Oil, Tranny Fluid, and Rear end fluid... so it's probably time for a radiator coolant flush since the coolant got so hot among other things. What would some suggestions be for things I should ask the dealership to look at if I brought it in there for a 75k mile checkup. Note I've always done all the work on it myself short of having the rear end changed to 4.77's by this dealership. I basicly want to make sure that 1. I didtn' do any damage to the car by having her in the Red for a few seconds and 2. That the car is still running well and getting the power it should. Taking this into consideration I know I'll want to ask for a compression test just to make sure everything is on the up and up there... what else would be a good idea to have checked and or changed right now? Any opinions welcome thanks!