I’m not a car guy. I want to be. I’m learning. I learn by making friends with mechanics and absorbing their information. I had a car a few months ago with some overheating issues. (Got it resolved. No water in my coolant at all, using straight concentrate in a brand new, empty radiator, like a dingus. 🤦🏼♂️) But before I fixed it, someone said it might have been the thermostat. I asked a mechanic friend of mine about it. (I haven’t known him long.) He told me he’s been a mechanic for right around a decade and has NEVER seen a thermostat issue cause overheating. Is he just totally out of touch? Or did I misunderstand how the cooling system of a vehicle works? Let me know.
Thermostats can fail in 2 ways.
They can fail open, which causes you to never get up to temperature. This isn’t good, but it’s not gonna risk catastrophic engine damage. Although your engine not getting up to temperature can accelerate premature wear, so it should still be fixed.
They can also fail closed. This is the one most people think of. Coolant simply can’t circulate properly and your engine overheats rather quickly. This is what causes bad head gaskets and the like if not spotted.
I’ve seen both types of failures multiple times, and had it happen to me once (failed closed in my case). It’s not implausible that he’s only seen failed opens, it’s just a bit strange.
Ask your mechanic friend what a thermostat jiggler valve is. It’s part of the thermostat. Google it. If he doesn’t know, stay away.
They fail two ways. That is one of them.
Oh if we try hard enough I bet we can get it to start on fire.
Coolant IS Flammable. Haha
I think he was probably having difficulty expressing himself.
Not sure why you wouldn’t believe him. I’ve never seen Gone With the Wind but I’m certain it exists
They usually fail open or closed. If open, the engine never fully warms up. If closed, the engine overheats.
Get a different mechanic
Hrmmm. my accord was overheating. Changed thermostat problem went away…
Of the four cars I’ve worked on in the last month that came in with an overheating concern, one was due to blown hoses at the junction to the heater core, one was due to improper bleeding after a radiator replacement, and two were due to stuck thermostats.
If this “mechanic” has never seen a stuck thermostat cause overheating, then I seriously doubt his 10 years of experience is doing much more than oil changes and pad slaps in the AutoZone parking lot. I’d cross him off the list of people to learn things from. He’s a hack.
In the 6 years of my experience, over 12000 cars went through our shop.
Not a single thermostat stuck closed.
As I prior tech for 40 … 2 cents here …seems to me newer thermostats are fail safe …over heat once and then slightly stays open …I haven’t seen stuck closed in seems like 10 years .
Had a brand new thermostat fail closed then the next failed open. Not buying that brand again.
I saw my first failed closed thermostat that caused overheating when I was 12…1967 Pontiac Executive. I’ve seen many more since. I don’t blame you for being gushy about out this mechanic.
Stuck open, stuck closed, and a failure to properly bleed the coolant system, bad radiator, bad water pump, and a coolant leak is the only way is know overheating problems occur
Do you count blown head gasket as coolant leak? Is a bad radiator fan or fan clutch looped into bad radiator? What about a clogged radiator? Not the water side, but with leaves and shit? Or how about bad radiator cap not letting the system pressurize?
Yes bad radiator includes all the radiator cooling components clogged etc. in my book, blown gasket you’ll be blowing white smoke, bad cap included
You need to find a new mechanic.
Thermostat fails, won’t open, no circulation to radiator, overheating. I have seen it a load of times over 40 years.
Your mechanic is wrong.
In the last decade alone, I’ve done about 6 or 7 thermostats. It isn’t common, but it is a thing for me. I’d say check your options other than this guy.