Can a thermostat grow lazy?

[fdcg27]

This morning, it was ~-2 or 3F on my thermometer.
I went out to start and idle the cars for a little bit, to determine that they would start, and to melt the heavy frost from the windows.
The Sube and both Accords all idled for at least ten and less than fifteen minutes.
Both Accords showed some coolant temp on the gauge, and the Subie, which lacks a gauge, had decent heat.
Shut all three down, took a shower, got dressed and left for work.
I was driving the '99 Accord, and noted that even while actually driving, not merely idling, it took an unusual amount of time to warm up.
Could the thermostat of the '99 have grown lazy in closing over the years?
I really don't relish replacing it in cold weather, but I think I may have to.

 

[SLCraig]

Yes, they grow lazy.
I have owned 3 Saturns, all bought inexpensively and used. Every one I buy ends up having a lazy thermostat. Not totally open, but not warming up the engine to where it should be.
A simple R&R and the cars run at the temp they are suppose to.
Even my 2000 wagon which I just got, had a bad thermostat. Replaced with a Stant 195 and all good now.

 

[gomes512]

To answer your question: yes.

Had to change the one on my '94 last yeas and in my '97 this year. Both were OEM Mopar and Toyota units respectively.

Same symptoms as yours

 

[sciphi]

To help without freezing your rear off, get some Coroplast or plastic-wrapped cardboard to toss over part of the radiator. It'll help the engine warm up faster, and keep the heat in. Just remember to yank it out when the temperature rises in the spring.

 

[rclint]

I don't think the get laze, they get stuck or work from what I have seen.. they either work or don't

I also own an accord, and I let my car idle this morning to warm up, and after 10 min it's usually warm, but not this morn in the upper teens I had to drive the car to bring it up to operating temp.. It did have some heat while idling, and showed about 2 marks below normal operating temp which is around 1/4 range. I think what your seeing is high heat use when really cold, and when you combine driving without much strain on the engine the cold can literally soak the heat away.. I doubt the thermostat even opens in the first 30 miles in these kind of temps here (20's at day teens at night) so all your running is the coolant in the engine.

edit to add my experience must be way off here from all the others having "lazy" thermostats... I guess the spring could grow weak, but I don't see how it could grow weak become lazy meaning partially work..

 

[fdcg27]

I would tend to agree with your theory, except that the '97 warmed up quickly on the restart, which was done to rearrange the driveway, while the '99 didn't.
Also, even in moderately cold weather, a stuck open thermostat is obvious.
The thermostat on the '97 stuck open a couple of years back, and even after miles of driving, the needle was barely off the bottom of the temperature gauge in ambient temps in the twenties, so I do think that you're right in saying that the thermostat stays closed for quite a long time in really cold weather.

 

[justinf89]

I just replaced the safari's thermostat this year. It was only getting up to about 160 in the summer when the thermostat's rated at 195. I put a new one in and it worked perfect.

 

[JHZR2]

I believe my system has gotten a small air bubble in it as my gauge doesn't go all the way up and has gotten a bit jumpy... I think the wide temperature swing has done it...

 

[JimPghPA]

If you use cardbord infront of the rad, be sure to remove it if the ambient air temperature goes back to or past 40 F. My brother put cardbord infront of the radiator of his car, and forgot about it. When the ambient air went up to 50 he got stranded with an overheated car with his kids. I had to travel to where he was, and then drive them home. The next day he remembered about the cardbord.

 

[NJC]

Yes they do get lazy, I even have riveting video proof. This one closed very slowly, and should have been fully shut after about 10s.



Replacing fixed my Honda's lack of lock-up trans.

 

[Audi Junkie]

Yes. A new premium thermostat cured the cel on our CRV.

 

[ChiTDI]

I'd be lazy too if I spent years in a Dex-C**l environment.
I use OEM for replacement.

 

[rclint]

Even if the thermostat becomes slow in operation.. which you would have to compare to a new of the exact same make etc to have good prof of that even happening, if it were slow it would not matter as long as it opened fully, close fully to acquire engine temp. I don't 100% doubt the lazy thermostat issue, but I have yet to see it.. the reason I don't doubt it is because of all the responses... still many said not getting up to operating temp that would mean a non working thermostat

 

[ronrackley]

I've seen thermostats stick closed and cause overheating more than once, too.

I drain and refill with antifreeze & distilled water every couple of years and change the thermostat at least every other time to avoid problems.

 

[fdcg27]

I've only seen one stick closed once, and the results were quick and unmistakable.
The engine (it was a really decent old Spridget, 1098 IIRC, that had sat in a garage for several years) reched operating temp and then passed it in a matter of minutes, although it was a warm summer day.
I appreciate all of the suggestions and moral support.
Since it is only the beginning of the cold season, I will need to brave the cold and change it.
Since I have heard differing opinions as to the quality of aftermarket thermostats, I will probably lighten my wallet a little more by buying an OEM one.
I did this with the other Accord, based upon my thinking that I really didn't want to do the change more than once.
It isn't hard on these cars, but it isn't really easy either.

 

[rclint]

as for malfunctioning thermostats what fdcg27 posted about sitting kills a thermostat, and other gaskets as well, and many other shafts, seals, bushings, bearings etc etc. I have seen a few done in by sitting

I had one in a Ford Ranger with around 200k on the clock zero problems fine engine, the thermostat stuck closed (only one I ever seen do that) but never registered on the temp gauge. I could not believe what happened, and noone else did, and chucked it up to me being young not paying attention.. BUT to save my good manhood at a young age working a full job, going to school (high school) and having to pay for the engine when I told the mechanic he took me back with him spent about 1 hour as he was intrigued. he started taking things apart, he just about pulled the head off ( I was paying him to put a head gasket on) then he took the thermostat out, showed that was not working on a heater etc.. then pulled the temp sensor out, and noticed no water in engine, he said the thermostat shut closed, blew all the water out, and he said without water it can run hot and not register on the gauge..

As to the head it cracked, I purchased a low mileage engine from local junk yard, and about 10k later a lady run a redlight clipped just the front bumper straight shot to the side, totaled my truck (warped frame, cracked transfer case) it was down hill from there with the insurance company etc

 

[mechtech2]

Thermostats can break in many ways.
Of course they can be lazy.
Unusual ambient temps are not the best test, though.