Glad you found the leak! That test kit comes in handy eh?

Just throwing this out there..... if the 1.4 bar relief cap doesn't operate under normal conditions, it will not help the system stay sealed any more than the 2 bar cap. If it does operate under normal conditions, it is not rated high enough for the system. A certain relief cap will not raise the MTBF of hoses / seals / expansion tank / etc. It is unrelated.

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Previously owned: '03 4.6iS Dinan Supercharged