Would a thermostat fail in OPEN position?

rabbit-1 · Jan 22, 2014

'00 Chevy Blazer, 4.3L engine... Engine temperature in the 140 to 150 range, heater barely working... Could the thermostat have failed in the open position?

3 Other Blazers in the family running 190+, heaters working well...

David G · Jan 22, 2014

Mine always have failed that way.

Nancy Howell · Jan 22, 2014

Yes. Thermostat on my Ford 7.3 diesel failed in the open position. Much better for them to fail open than closed.

pete black · Jan 22, 2014

check coolant level?

D beatty · Jan 22, 2014

There is a thermostat on the market that if it fails it will always fail in the open position.I put them in my vehicles to be safe. If they stuck closed I'am not sure my wife would stop before it got to hot.

patiolant · Jan 22, 2014

Had an '04 Blazer do that

D beatty · Jan 22, 2014

That type of a thermostat is called a failsafe thermostat. If they go bad they never atick closed.

kj(seil) · Jan 22, 2014

yes they will and low coolant can cause same

MSS3020 · Jan 22, 2014

funny you should ask this.. my 2000 F250 had minimal heat at best..NEW to me a year now. I was told could be that very problem.. I drained and flushed the system and replaced thermostat and just because I put in a new heater core.. Works perfect.. I guess as Nancy said would rather it be open then stay closed..

teddy52food · Jan 22, 2014

They get too hot in the summer time & that over strains them to where they don't close again.

Anonymous-0 · Jan 22, 2014

Had one on 77 chev that never reached max temp. Took it out and compared with new one over teakettle in steam. They both opened together but the new one closed fast the old one hung open a long time. The new one brought the temp up to spec.
Later Bob

Allan in NE · Jan 22, 2014

Check your coolant level, check the thermostat and if both are okay, next stop would be the intake gaskets.

Allan

Leroy · Jan 22, 2014

Just had that happen the last cold snap on my 98 Voyager

Steve@Advance · Jan 22, 2014

No doubt at all, that is definitely the problem. Very common.

Joe Blackeby · Jan 22, 2014

Just went thru that with a 2000 S-10.
Have flushed it twice since new (leftover) That orange anti-freeze (GM) is the problem. Inside of radiator has a layer of ???? No heat, but engine overheating.
Replace thermostat and flush. This makes the forth set of thermostats, antifreeze and flush. Container of orange anti. says 150,000 miles.My truck turned 115,000 miles. Think they lied!

Super-H-Mike · Jan 22, 2014

Yeah they can and do fail open, or they can physically break too. It doesnt have to fail wide open either, it can be that it just doesnt seal shut all the way and in cold weather the engine wont heat all the way up. Take a close look at it when you get it out, you may spot the trouble.

old · Jan 22, 2014

Like any other mechanical device a thermostat can fail in any position. Open closed or some where between

big jt · Jan 22, 2014

Engine overheating and heater not putting out anything?

Me thinks you should look at your coolant pump.

jt

Anonymous-0 · Jan 22, 2014

The Blazer's are known for plugged heater cores too. You can flush them out with a garden hose.

gab · Jan 22, 2014

Yes, it can stick open. I have a 97 Jimmy that the gauge reads about 155 and heats good, plugged a scanner in to it and it's 195 so gauge is off. Some of those little Blazers would plug the heater core bad, take hoses off engine and flush with a garden hose. Some of the radiator caps leaked down the side of the rad. tank and sooner or later it's gonna need intake gaskits
I think there used to be a serv bulletin that said the cause of the dex cool antifreeze sludge was air getting in to it, never had any trouble with mine.

GBCMAN · Jan 22, 2014

Same problem with my 2000 GMC Sonoma.
You flush it, change thermostat and anti-freeze and a year later the anti-freeze has rust in it.
There"s a bulletin on this problem for Chevrolet/ GMC .Just google it.

60 acre hillside · Jan 22, 2014

That is the way they most commonly fail. Sometimes takes longer to detect than one stuck closed.

Would a thermostat fail in OPEN position?

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