I would change the cap too if you haven't already decided on it. It's an inexpensive part and they do wear out since they are under pressure. If you're changing your coolant reservoir anyway, order the $7 cap to go with it.

As far as your water pump, your mileage is kind of low for it but it couldn't hurt if you're doing a coolant flush. Then if you do that, you might consider changing out the serpentine belt too since you're in there. It would all be prophylactic and would give you some peace of mind but you might not even need to replace those parts.

I needed to change my belt so while I was at it I swapped out the water pump, even though there was nothing wrong with it. I did it out of paranoia that it was a plastic impeller version and would give out any minute.

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