Thermostat replacement?

Post by **Roger_850T** » 26 Jan 2019, 16:05

I'm curious. Would you consider a thermostat to be a "wear item" to be replaced at regular intervals just because it's got some miles on it?

I've already got my Volvo apart. (2005 XC90 V8, 140k miles.)

It's not like the aux belt pulleys or tensioner, which have bearings that wear. And I'm replacing the water pump too, because it has bearings and seals that can fail.

I am trying to decide if I should also replace the thermostat. No bearings, no seals. Generally I've only had thermostat failures after replacing them "just because", so there is an argument for leaving it alone and avoiding infant mortality issues.

What do you think? Is there a good reason why I should replace it prophylactically? Or should I leave the old one in there? Discussion please. Thanks.

Roger

Post by **cn90** » 26 Jan 2019, 16:39

Yes,

Most thermostat soft fail (open too early) at around 80K-100K.
I routinely replace my thermostat every 80K-100K.

Masscomguru · Post by **Masscomguru** » 26 Jan 2019, 17:55

The spring which allows it to open at temp fails from the heat cycles.