excessive coolant flowing into the overflow
 

Hello, I'm trying to figure out an overheating issue with my 95 turbo na. I just replaced the thermostat, radiator cap, radiator, did a begi coolant reroute, and installed a cometic head gasket. I bled the cooling system by removing a top plug in the thermostat spacer and filling the radiator until I saw a very steady flow out of the hole, re installed the plug then topped off the radiator. When I drive the car the cooling system works perfectly fine until I've been on the road for ~20 minutes. Then my factory temp gauge slowly starts getting hotter then cooling down, then a little hotter, then cooling, until it heads for the H. However my gauge on my megasquirt never gets over 215. After I let it cool down and remove the radiator cap the coolant was about an eighth of a gallon low. So today I let it idle for a good long time and noticed that my radiator is spewing a good bit of coolant into the overflow. Any ideas what could cause all of this?

thanks,
Chris

It appears like the rad cap is not sealing. Check for air, try again, get an extra cap. I'm not sure what pressure cap because it's too hot to leave my air conditioned apartment for the garage.

coolant pressure test? i saw they rent them at pep boys. i had a similar issue. i had a loose hose clamp.

Sounds like its all sealing. Remember, if the rad cap doesnt seal it is impossible to get over 225*F with a 50/50 mix, and impossible to get over 212 with straight water, until there is zero coolant left, because thermodynamics.

I'm pretty sure everything is sealing properly. If I remember correctly the factory cap is like 15psi and the one i installed was 18 psi. I will try installing a new 15psi cap and see if it helps any

If your coolant is going into the overflow only when it's hot, then the radiator cap should be working fine.

Your oil color ok? No coolant in your oil?

I know the last time I had excessive coolant going into my coolant reservoir was because of a botched head gasket job I did after no cleaning the mating surfaces well enough. Went into boost and bam, I knew exactly what I had screwed up. Popped the hood and my reservoir was completely overflowing. Wasn't overheating or anything. Never went above 200 degrees in tunerstudio either

I've had that issue years ago with an inconsistent radiator cap. Went back to stock and problem was solved. Try a stock one if you have it laying around before you start getting deeper.

I had the same problem in my integra a while ago. I did all the things you did trying to trouble shoot it but it did end up being my aftermarket rad. Cap. Guess it didn't have the proper seal or something