Is it time to upgrade my head bolts?

[Demon33]

I've had my e316g turbo installed for about a year now and ever since then, I've pushed coolant passed the radiator cap and into the coolant overflow bottle when boost was 20 psi or more. I installed a 1.3 bar (19 psi) radiator cap and the problem went away, but the increased coolant pressure has always conderned me.

Today, as I tuned with boost increased to about 25 psi, my water pump blew the o-ring seal at the coolant tube connection. I'm guessing it was because of the increased pressure of the radiator cap and possibly my head lifting a little causing the coolant pressure to increase even more.

Does anyone know what causes coolant to be "pushed"? Is it the head lifting slightly or some other cause?

Is it time for me to upgrade my stock 6-bolt head bolts to stronger ones? If so, what do you recommend for a daily driver tuning with LinkV3 on 91 octane and 50/50 meth injection running 20-25psi max boost?

 

[gofer]

Its not time to JUST upgrade to head studs its time for you to replace your headgasket, I recommend ARP studs and a Mitsu composite hg.

When your head lifts instead of pressurizing just the cylinders with air your also pressurizing your coolant jackets, which in turn pressurizes the coolant hoses. Thats what causes the coolant to "push" out to the overflow bottle because at 17psi (or 19psi now) the radiator cap opens up. Your radiator hoses are always "plump" looking too because they have 19psi of air in them ALL the time...

 

[Demon33]

Its not time to JUST upgrade to head studs its time for you to replace your headgasket, I recommend ARP studs and a Mitsu composite hg.

When your head lifts instead of pressurizing just the cylinders with air your also pressurizing your coolant jackets, which in turn pressurizes the coolant hoses. Thats what causes the coolant to "push" out to the overflow bottle because at 17psi (or 19psi now) the radiator cap opens up. Your radiator hoses are always "plump" looking too because they have 19psi of air in them ALL the time...

Since I have to pull the water pump, all the timing stuff and the head bolts, I might as well replace the head gasket now. I've used a stock OEM head gasket for years now without issue. Would the composite offer better or longer life and be less likely to fail? What advantage does it have over the stock head gasket?

Will upgraded head bolts and head gasket stop the coolant from being pushed? I'd love to go back to the lower pressure stock radiator cap if possible.