Happy Thankgiving

The coolant system is designed to run under pressure which is controlled by the reservoir cap. Your 2 yr old radiator most likely did not cause blow out the reservoir, even if the system overheated, it was most likely a faulty cap not releasing pressure or the reservoir was old, weakened and ready to blow. The cap is designed to relieve normal pressure as it builds up. If running without a cap you will experience puking of fluid especially right after shutting off the engine.

Water pump cannot cause overheating and cannot cut out as it is belt driven. Typically the only thing that goes wrong with a water pump is that it slowly leaks fluid out the front seal when it gets old which then results in overheating.

You do not mention if you have a 960 or 940 but I believe you should have a 150kpa cap.
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David Hunter