What is the OEM temperature for a thermostat?
Also, I see there's a thermostat designed to protect against overheating. Is this of any value to install instead of the regular thermostats? Thanks


Patented safeguard against overheating. When overheating occurs, Fail-Safe automatically locks in the open position to permit maximum coolant flow. Manufactured from high quality components to meet the demanding conditions of the automotive cooling system. Manufactured with OEM specifications and processes. Copper case and wax compound assures rapid response to temperature changes in the coolant. Offset design, air relief valve, and OEM style seals included where applicable.
Helps protect your engine from overheating
Engineered to permit continuous flow of coolant when overheating occurs
High grade stainless steel and copper construction
Meets or exceeds OEM standards
Consistent and precise response to cooling system needs
100% tested and calibrated

http://www.autozone.com/autozone/parts/Failsafe-Thermostat/1980-Volvo-242DL/_/N-imby1Z8gctr?itemIdentifier=710629_413832_1633_93207

you're being hustled if you spend the money to buy one of these.

let me ask you this:

1. what if the radiator leaks?
2. what if the head gasket leaks?
3. what if a coolant hose leaks?
4. what if the heater core leaks?

everyone of these will cause your engine to overheat or much worse.

what difference will having this magic thermostat installed make?

I looked at the link you gave ... I don't know if that's any better than the OEM thermostats.

Yes, it seems from the picture to have a more robust frame than OEM -- and I have seen pictures of a thermostat whose frame broke from corrosion; but that's most likely from neglect -- you shouldn't expect a thermostat to last 20 years. Change the thermostat when you change the coolant (again, more often than once every 20 years :-).

Other than that, it's claim, "...When overheating occurs, Fail-Safe automatically locks in the open position to permit maximum coolant flow...." is *NOT* anything special! All thermostats should be wide open when hot. That claim is just marketing hype!
Likewise for the other attributes -- they're just reiterating what all thermostats provide in grandiose phrasing.

On the negative side, they don't even include a new gasket??? That's important, and if they're so eager to protect your engine, they should include it -- otherwise they're just nickel-and-diming you for the gasket, so you should ask where else have they cut corners to save a few pennies.

A quick bit of search on thermostat failure modes indicates these thermostats can also fail closed, as well as open. Based on that, I'll stick with the Wahler thermostats I've been using and having good experiences with.

I do coolant changes every two years and replace every two or three changes. I keep the used and now proven thermostats in my onboard cross country parts collection (with a new gasket).

If someone had a fail-safe that ALWAYS failed open, I'd use that. However, it appears these ain't them!

I use the higher temp rating of 92 degrees (which the FCP catalog claims is the OEM rating).

Tatra Mike

Seattle, Washington

1985 244 "Alfsen" (wife's car - the good one)
1984 245 "Buster" (the kid's car, now sold)
1985 245 "Cosmo" (parts car, sold off for move to WA)
1985 245 "Daisy" (back seat down, full of tools, the work truck)
1985 245 "Earl (CA vehicle 'retirement' program)

Can you tell I prefer the 1985 model 240? Better headlights than
the plastic 1986+ and nicer belt adjustments than the 1984s and earlier!