I posted a while back about having issues with the cooling system and I still do. Here is what has happened since.

A couple of mornings went to start the car and drive to work to only find myself pulled over on the side of the road 5 min later. The temp would go up so quickly in a matter of less than one minute.

The following week started to notice that the antifreeze, like if I drove tonight and parked it till next morning, the reservoir level would be at the max line which is fine. Now, next morning it would be over the line.

Today, I dumped the reservoir into the radiator and made sure the rad was full. Went for a long spirited driving and when i pulled over. The antifreeze is now back into the reservoir almost ready to spill out.

So after that i took the car and put an emmissions probe into the radiator just above the water level, and it showed about 30 particles of hydrocarbons.

We think that compression specially when driving hard is making, is making its way into the radiator and therefore pushing out the water into the reservoir. The thing also is that it will not pull the water back into the rad when sitting overnight.
I do have the 3mm headgasket , low temp switch and thermostat by Mugen

Any ideas are welcome.

 

Sounds like you need to get the engine to operating temp and perform a leakdown test with the radiator cap off.

If you see air bubbles come out of the radiator, the headgasket is blown, or there is a crack in the combustion chamber. Doubtfull there is a crack in the bore, otherwise it wouldn't make much power and have lots of white smoke in the exhaust.

Most likely a blown/leaky headgasket.

 

Dude! what up with that avatar?

We had about 26 ppm on the HC at the tailpipe, and hit almost 40 at the rad, which is more than the tailpipe.

Right off the bat I say headgasket/head

I was trying to think if there was any part of the engine I missed that could allow combustion (or crankcase) pressure into the cooling system...wishful thinking?

 

40ppm? Definitely blown/leaky. Are you using stock headbolts or headstuds?

 

Studs w/ 3mm gasket...

 

Whose studs are being used?
Where they re-torqued?
Any signs of oil weepage around the head?

I've seen several non-S2000 motors with lots of boost have some head "lifting" using ARP studs.

 

As an update and to start fresh.

I just went out for a spirited drive and made sure the radiator was topped off and the reservoir was filled to the line.

After I came back from the spirited drive about a 1/2 later. The reservoir was overfull about 2 inches over the line

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Im using AEBS studs
i did check the torque probably about 2 weeks later, (although the car didn't get driven very much) but haven't checked again since. hmmmm


Actually since you mention oil weepage,'ve noticed quite a bit of difference in oil consumption, but i attributed to my leaky Greddy oil adapter which I have to replace. But I see nothing obvious around the head.

I dont think these studs are made by ARP, AEBS said someone else made it for them.

So can we assume that at this point I may need to retorque again? The car feel strong I guess throughout all gears. I see between 11-12psi with a 3.5" pulley after its gone through the FMIC.

 

The avatar?

Well, I was bored but now I see the change in avatar came in handy, couldn't stand looking at my engine bay avatar anymore specially now w/ this BS happening.

And thanks for the ppm clarification, forgot what the number was.

And also thanks for the probe check

 

Did you follow AEBS instructions of torquing the studs in the block 1st to 10ft/lbs?

You will have to remove the Cams and rocker shafts/stands to retorque the nuts.

 

This may be very incidental compared to the suggestions already posted. How tight is the hose connection between the rad filler neck and the reservoir. If it's loose, it will convey fluid to the reservoir as the coolant expands but will not pull back in when the engine cools down. I've gotten into a habit of putting small hose clamps at the rad cap end and at least checking the end where it connects to the overflow tank.