If tensioner, pully and roller were replaced at 140K miles, then it's still good. If not, then replace all of them. If in doubt, go ahead and do them. This is peace of mind- if one of these goes, so can the TB. Check condition of seals. If they look good with no weeping, then don't worry about them. If water pump has never been replaced before, you're lucky it lasted this long. It Needs replacing now. You'll need the water pump with it's gasket. Also, the Serp. belt has to come off anyway for the TB. When was the last time it was replaced? Every other Serp. belt replacement, you should replace its tensioner as well. If this hasn't been done, then go for it too. All in all, Serp. belts are lasting as long as TB's, so if you go ahead and replace it, it won't have to be done until 280K miles with the next TB. Good luck!
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1998 S70 T5 Emarald Green Metallic (125K), 2004 V70 2.5T Ruby Red (45K), Previous Owner of Black '94 850 Turbo Wagon (Sold at 140K and miss her). My cars have been running so well lately they've got me worried.