combustion in the coolant?

[Dead Parrot]

2nd on the cap releasing pressure before the radiator splits. Get a new cap even if current one is fairly new. QC could have failed.

Could be possible that you have a small enough head gasket leak or crack to let combustion air into the water spaces but not water back into the cylinder. Once the fire lights, pressures get really high, hundreds if not into the low thousands of PSI. The max for the water should be the cap rating. Test run it with full water but cap off. If there is leakage, you should see bubbles in the radiator.

Are the radiators leaking from the same spot? Maybe some assembly person needs a bit of additional training.

Nice to hear that a company stands behind their products.