2009 XC90 3.2 Thermostat Replacement Interval

thebull · Post by **thebull** » 16 Nov 2015, 21:44

Hi all! Do you know the service interval for the thermostat. I asked local dealership and they told me that there is no specific interval for replacement and needs to be changed only if there is a problem.
Wahler thermostat needs to be changed every three years. XC90 3.2 liters engine thermostat is different. Do you have any info on service intervals? I know if there is a problem with thermostat could be very, very expensive. Is this none serviceable item like the "lifelong" transmission fluid?
Recommendations, thoughts?

Thank you.

Ou2mame · Post by **Ou2mame** » 17 Nov 2015, 15:16

I only change it if I have to take it out for something else, unless it's broke obviously. You can replace it whenever you want. Or when it breaks. You'll probably want to replace it when it breaks so that decision will eventually be made for you. The thermostat will only cause expensive problems if you drive the car while it's overheating, so if it overheats, don't drive it. Normally these break in the open position so you have a few symptoms to guide your decision making process. Decreased heat in the cabin, engine taking a while to get up to temp.. Etc.

Post by **oragex** » 17 Nov 2015, 16:47

The dealer is right, as Ou2mame mentions, these stats usually fails in open position (does not fully close any long) so the coolant won't overheat but rather the engine will run cooler than normal. I'd expect the original Volvo stat to fail after about 8 years. One easy was to test if it's failed is to start on a cold engine, let it idle for about 2 minutes then touch the upper thick hose that goes from the stat to the radiator. If the hose is warm-ish in the middle it means the stat doesn't fully close any long so it has failed.

Post by **cn90** » 17 Nov 2015, 17:22

No matter what car you drive, most thermostats fail around 60K-80K time.
Just like tires, brakes etc.
These things only last that long.

If you are lucky, it fails in OPEN position, which still allows you to drive.
If it fails in the CLOSED position, your engine will overheat.

thebull · Post by **thebull** » 18 Nov 2015, 14:35

Thanks. I got the idea for the intervals.

Do you think all new thermostats are engineered in the way if they failed to stay in open position?

Ou2mame · Post by **Ou2mame** » 18 Nov 2015, 15:03

It really depends on the conditions. They *should* break open, but I wouldn't bet my motor on it. I'm at 150k on a stock one in my xc90. My audi had 125k when it's failed. They last a while.

Post by **oragex** » 31 Aug 2018, 08:42

Sorry, I want to correct my above answer, the thermostat on the 3.2 engine has a fragile plastic housing and fails after about 8 years and causes the engine to overheat. Replace no longer than after 8 years

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