I just had a 180* Failsafe thermostat lock in the open position on me. I couldn't get any heat so I opted for a 195* unit but when I took out the old one it was locked in the open position.

I took it back to the parts store and they tell me I have an overheating problem.

But the car has NEVER overheated, even with my old style 195* thermostat!

My gauge seldom gets very far over the 40*C mark, except when I'm in stop and go on a hot day. I've NEVER seen it hit the red zone, period! The water pump and radiator are both only a year old. I just replaced the heads two weeks ago.

What is going on?

Are these Failsafe thermostats just a load of bunk that are too sensitive and lock for no reason, or what has been you folks' experiences with them?

 

ttt

 

Some one at the parts store is feeding you The fail safe refers only to if the thermostat fails, it fails open not closed.
Some of the old designs failed closed and so you were more or less guaranteed the engine would overheat when the thermostat quit working.
No way should the thermostat fail due to overheating. That would be virtually impossible, because the engine would seize up well before it got hot enough to damage a proper thermostat.
How long did you have the thermostat in the engine?

 

Maybe a month or so.

The store says that when the thermostat is heated to a certain temp that it locks in the open position. The "failsafe" device goes into operation, causing the spring to move up and be locked by the hangers on each side. They tell me that it must hit some horrendous temp for this to happen, so if it IS locked it is PROOF that the engine is overheating. I told the guy my engine has never overheated but he thinks I'm not aware of what's happening under my own hood.

My advice? Throw away those failsafe jobbies and get a regular thermostat.

 

It sounds like the store is making it up as they go along. What would be the point of a thermostat jamming open with a hot engine. At best it sounds like a design fault being turned into a feature. I would ask the store for the writen instructions that back up their story.

 

what is the name of this 'failsafe' thermostat.. i would just go get a regular thermostat.. they are pretty failsafe by design anyways

 

They are called "Failsafe." That's what is on the box.

Their advantage is supposedly locking in the open position if it fails, so the engine doesn't overheat.

 

Isn't it made by Motorad?

 

Hi
That is correct that they fail open and not closed which makes them safe when they fail. But the store suggesting that they stick open when the engine overheats is wrong. They should replace the stat with a new one, because the one that stuck open failed too soon, and not because the car got too hot.

 

Yes it is.

 

I agree.

And the one I replaced it with seems to have gone bad, too.

 

My buddies and I went through this whole fiasco with Canadian Tire - he bought 4 in total from them, and each one failed open (So he couldn't return it). Finally he hacked it so that the failsafe part was gone and it worked good.

I had one too that failed on me, put in one of his 'custom' ones and worked perfect.

These all happened on DSM's, but I have NEVER used a fail-safe since. I was lucky - it was only about -10 when mine went. But my buddy has his go when it was -30. So much for him having kids...

 

I believe your pall who suffered the - 30 and no heat will be OK . Apparently the body has ways to keep important part working when the temperature changes for the worst. Which is more than can be said for those fail safe thermostats.