The serpentine belt in my 03 Cooper S broke recently and some of the coolant overflowed, so I decided its a good time to do a coolant flush. After searching the forums, it seems like it is a bit tricky to do a proper coolant flush. So I called a local Mini specialist about doing the flush. They recommended that I go ahead and change the thermostat. My car only has 36K miles on it, but he says that because of the age of the car, the thermostat will start leaking soon.

My question is if this is true, and if I should go ahead and change the thermostat with the coolant flush.

Thanks in advance.

PS. I posted this earlier, but it didn't seem to show up. I hope that it didn't get posted twice.

 

When you say the coolant overflowed, what does that mean? Did it boil over because there was no belt to spin the coolant pump? Was the thermostat exposed to coolant temp beyond the normal range?

It that is the case, then it would be a good idea to replace the thermostat. Exposure to higher than normal operating temp can eventually cause a thermostat to malfunction.

If not, I wouldn't touch it. None of my cars had faulty thermostat till pass 150k. The one on my Mini was replaced by the dealer due to a leak on the thermostat housing.

 

The coolant boiled over because it heated up when the water pump stopped turning. I was very close to home so I drove it like that for about 2-3 minutes so I could get home.

 

Should replace it.

 

I would replace it if you've never had it replaced before. The gaskets on older versions are known to leak I've had two fail on my 06 already. If you are doing the flush you might as well do it now.

 

As Rossii says. Since the gasket is only sold together with the thermostat, get them both and do it along with the other coolant system work you're doing.

 

We've had the weeping thermostat gasket issue on both of our '06s, so I would agree that replacing the thermostat/gasket "on speculation" probably isn't overkill.

 

I just replace my 02 MCS. It's easy to replace but I see no reason to replace yours. Mine was still fine.

Running a high temp shouldn't hurt the thermostat and if it's not leaking it should be fine. I recommend that you put your ECM into the service mode and watch the actual water temp. Turn off a/c. At appx 105C the fan should kick on. You'll see the temp drop immediately. My high temp problem was a bad pressure cap (lid) on the overflow tank. I was boiling over right at 105C. The cap should hold pressure beyond 105. That why its important to put the computer in the service mode.

 

I'd be in the "if it ain't broke, don't fix it" camp on this one. Thermostats should be replaced if you're in there or they're having problems, but I don't view them as a regular replacement item, even on a Mini. (Neither does Mini, BTW.) I've never heard that a brief overheating episode will damage them either.

- Mark