Rav4 water pump - when should I replace it?

I've had my Toyota RAV4 diesel from new. It is well looked after and fully service. It has 118,000 plus miles and no obvious problems. As this is chain driven what should I do about water pump?
It's probably quite expensive to get at. Good idea to change the coolant (for more of the correct Toyota coolant). Check the level at least every week for leaks. No clear data on when they can be expected to fail. I thought from hearsay that on the Prius (also chain cam) it was about 200,000 miles.
Answered by Honest John on

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