I thought it might be interesting to do a poll and see at what kms people have had thermostat failures in their 3rd gens. So here goes.

I consider them service items. Replace during major service.

Hasn't happened yet, done 212,000km

Less than $50 for peace of mind. Yes please.

Replacing at the major service is a great idea but it is certainly interesting to see when they do fail. Might give other members the stimulus to do theirs at the next service.

If you're forking out at least $3-400 in parts at a major service, why not do your thermostat at the same time?

Using long life coolant will last 2 years. When I flush coolant, I like to do the top and bottom radiator hoses and the thermostat at the same time. it's just preventative maintenance. I can get those little buggers genuine for $24. I think retail is $40. Not really an expensive exercise for me.

Although not a 3rd gen, mine failed at around 115,000k.
Other than the notorious 380 window regulator failure, only failure I've ever had in well over 100,000k of ownership.
The water pump on my old TE failed at around 160,000k but the thermostat was still OK when I sold it at 206,xxxk.
Seems that Magna & 380 thermostats and water pumps fail almost at random once they get over 100,000k. Some will fail not much past 100,000k, others will keep going OK to 300,000k plus. The thermostat is a cheap & easy DIY replacement, so I'd be looking to replace it every 100,000k or so. The water pump is not so cheap or easy to DIY, but most mechanics (including Mal) reckon you should change it with every second timing belt replacement, ie every 200,000k.

Not a big believer in replacing a thermostat just in case it may fail down the track.
What if you replace a thermostat that was destined to go 300K with one that is destined to fail at 50K Km? lol
Items that are part of the service schedule, or hard to get to items like the water pump, are a different matter.

My old TE had over 230,000 on the original, and my current TJ has over 200,000 on the original. Never had a failure.

Going by Murphy's Law, I shall expect a failure this evening.

Not a big believer in replacing a thermostat just in case it may fail down the track.
What if you replace a thermostat that was destined to go 300K with one that is destined to fail at 50K Km? lol
Items that are part of the service schedule, or hard to get to items like the water pump, are a different matter.

Hope you are sitting down Max but I agree with you 100% here

Replacing parts just because is a total waste of time and money and totally senseless. Items which are known to have an average life span sure, things like water pumps because it is a very involved job to access. Things like radiator hoses every 2 years (and are you going to change the heater hoses, the bypass valve hoses, the heater core "O" rings and all the other "O" rings in the cooling system as they are all rubber and all should be then done as "preventative maintenance"), thermostat every main service......

I will concede that the 380's seem to be going through thermostats so "perhaps" but then again I have customers with over 200+k on their 380's and still no issues. I have seen Magna's with over 400k on them with no issues. True you dont know what has happened to that car over the last 10 years but being a specialist I think I would know if this was a common occurrance and I can tell you it is not. I know there will be a few here who will state that their thermostat did go but lets be a little realistic, like the wave spring poll, about 1% of the total of cars made out of tonsley belong to members here, take away those with no problems and you have such a small percentage of issues it does not even warrant the space taken up on the server for this thread :)

I guess I gave gotten a little nervous about them after coming within an inch of cooking my pristine Ralliart. Must admit I had not heard of many issues with them after having Magnas in the family since the 90s. As Mal said, 99% of people won't have issues with them. I was probably just unlucky. The 42 degree day brought the issue out quick smart so I was close to home.

I have seen plenty of thermostats go. Most disasterous of which, a tf thermostat failed on the hume highway near Goulburn. Car wouldn't cool down, kept driving till he reached Mittagong. warped heads. The guy was quoted $800 for new engine + 6 hours labour @ $88 an hour. Towie was $300 back to Sydney. Car went to the scrap heap, he now drives a corolla.

Thermostats are cheap, I don't understand why people wait to be on the side of the road before getting a new one.

My sister's 1998 TF Magna now has 311,000km on it and is still on it's original thermostat, as well as all original hoses.. all function as efficiently as it was when new.

I have seen plenty of thermostats go. Most disasterous of which, a tf thermostat failed on the hume highway near Goulburn. Car wouldn't cool down, kept driving till he reached Mittagong. warped heads. The guy was quoted $800 for new engine + 6 hours labour @ $88 an hour. Towie was $300 back to Sydney. Car went to the scrap heap, he now drives a corolla.

Thermostats are cheap, I don't understand why people wait to be on the side of the road before getting a new one.

Would have been just the tow and a thermostat if he had not made that decision to keep driving.
You could always have a new one in the glove box and coolant in the boot to avoid this sort of situation. (It's called "carrying spares", people used to do this all the time in the Old Days.)

Many people aren't so mechanically minded.

The only problem I've had with them is the engine not getting hot enough, never over heating problems thanks goodness, i bought a TS 2.6 6 months ago and was running too cold, easy fix, same with my KH running to cold when I bought it. the TS had done 140,000 k's and the KH 203,000 K's

I have seen plenty of thermostats go. Most disasterous of which, a tf thermostat failed on the hume highway near Goulburn. Car wouldn't cool down, kept driving till he reached Mittagong. warped heads. The guy was quoted $800 for new engine + 6 hours labour @ $88 an hour. Towie was $300 back to Sydney. Car went to the scrap heap, he now drives a corolla.

Thermostats are cheap, I don't understand why people wait to be on the side of the road before getting a new one.

People that drive a car that's running way too hot are asking for trouble really, that's why they have a temperature gauge and if the driver ignores it well thats what can happen, carry some tools on a trip and take the thermostat out if its running way too hot.

Many people aren't so mechanically minded.

and they pay the price for their lack of interest.

could the poll be improved by adding a "not failed yet" option?

could the poll be improved by adding a "not failed yet" option?

Good idea.