Radiator keeps blowing up when pushing the car

[alekseykorzun]

I have 540i/6 (swapped from automatic, brand new motor) two new radiators in the row pop around the neck area after 1~ hour of 'hard' driving. (near red line pulls, etc).

There is no overheating when driving 'spiritually'/daily nor is there any overheating when pushing it but every time I push it to extended period of time radiator pops.

Fan clutch,water,thermostat are brand new.

Any ideas guys? I don't think it should fail even when driven hard.

P.S 50/50 BMW coolant mix with distilled water + 4 shots of red line water wetter.

[dusty21]

1) Over-tightened hose clamp around neck?

2) Coolant Cap not releasing pressure?

3) Sometimes head gaskets will "burp" exhaust gas into the
coolant under high loads, but will be o.k. when under
light loads (this happened for weeks with my 535i)

[alekseykorzun]

I have purchased new cap for previous radiator and it still blew up, I was pushing the car for about an hour in 80F weather.

There is no overtightened since the break happened in upper left part of metal fins.

:\

[tem]

Just after slowing down, it would go for the red zone. Turned out the be the temperature switch on the side of the radiator. Apparently, you need both the thermal clutch fan and the electric fan.

[KSKarl]

Even though you got a new radiator cap, get it pressure checked. The system is getting over pressurized, and the cap is not venting the pressure.