Are you running OEM head studs? Why not upgrade to ARP. Did you notice carbon on the deck of the block when you removed the HG that would show exhaust pushing into places it's not supposed to be?

If you havent done this, remove the head cover and retorque the studs to 85lb/ft to make sure. I had exact same problem, few month ago. turned out the shop that put my head on torque them to 75lb/ft and obviosly that wasnt quite enough.

Let us know if it helps.

definitely not using the stock headstuds (arp are in it's place). the studs were torqued to 75ft-lbs. when i take the head off again (for the 5th time!) they will be torqued to 85. but for some reason i don't that is the problem, although a good idea. i've had the head checked already for cracks or pin holes because it was ported, but to no avail. this time i'm going to have the block and head decked. and i might use a new set of studs. i'm also looking to have the head o-ringed. we'll see what happens. thanks for the input.

by the way, i'm running about 30psi which tappers off to about 26psi on california 91 pump fyi.

also check simple things such as the radiator cap itself....

pressure tested the cap and it was fine. i changed it anyways.

give the studs 10 lbs more tq and go from there before you take the block out to be decked.

If the studs were torqued to 75lb, i am positive, thats what it is. Same problem as I had, anything over 17 PSI would kick coolant out. (I also have ported stage 3 head).


Best of luck

Detonation is also something that could definitely be a huge factor with your problem. If you are running that much boost on ****ty cali 91 octane gas I'd check for detonation. That would increase the cylinder pressure by tremendous amounts alone!

Similar issue here. Actually the same issue.
GT35r car, still a 2.0.

I can flog her all I want on a cool night, doesnt use or lose a drop of coolant. Do that on a warm day say near 80 or 90 degrees and its bye bye baby to the coolant. It will evacuate everytime.

Ive tried removing the thermostat, I ve tried water wetter. Ive torqued my head to 120 foot pounds.

Everything is fine unless its hot outside, which lends me to think its not a HG issue at all, but a insuffectient radiator/ air flow issue. If it was an HG issue, it wouldnt matter if it was cold outside or warm... If it was leaking under duress (at more than 25psi) I doubt 20 degrees cooler or warmer outside ambient air temp, is going to make the hg leak vs not.


That being said, I'll toss in a lower thermostat, and get the most powerful radiator cap/spring I can buy... Since I drive the thing on hot days, I need to come up with a fix, because making two pulls and having to fill the radiator back up is for the birds.

Do you have a logger? Wideband? What does your knock look like? What does your AFR look like? Compression test? Most likely your head is lifting or your block is warped.

you would destroy your engine due to running too hot before you touched the boiloff point of coolant under pressure. its impossible that is happening without seriously damaging your engine.