What would make a thermostat go bad?



#1
Hi, my 98 Integra LS 1.8L DOHC is giving me alot of overheating problems lately and mainly i keep going through thermostats. Most recently i replaced my thermostat with a duralast a week ago and it already is giving me symptoms of being bad again. I tested both my old one and new one before replacing. The one i removed was bad and didnt open all the way, the new one worked fine opening at 165f.
Today i had the same symptoms as before with the car overheating when idling at stop lights and such. When i drive the temp seems to drop back down. This is the same problem as i had before and i replaced the thermostat, what would cause it to go bad again? Is there another problem i should be looking for?
As well as the car overheating this time, the radiator hose coming out of the thermostat housing has swollen up and the hose is hot to the touch.
Please let me know if there is anything you may suggest that i should try instead, otherwise all i know is to replace the thermostat again. I have done this 4 times in 3 years however. It always seems to fix the problem when i do but never seems to last very long.
Thanks
 


#2
Could be a bad coolant/water mix, or you used tap water versus distilled water. I have heard that coolant contains some lubricants to keep parts like the thermostat sliding properly. Having distilled water versus tap water helps resist corrosion (particularly in the metal water pipe behind the engine).

It overheating at idle and dropping back down when moving sounds more like the fan is not working properly, to move air through the radiator at stops. I would look into that before replacing the thermostat over and over.
 

Merlins Beard

*Beard not included
#3
Could be a bad coolant/water mix, or you used tap water versus distilled water. I have heard that coolant contains some lubricants to keep parts like the thermostat sliding properly. Having distilled water versus tap water helps resist corrosion (particularly in the metal water pipe behind the engine).

It overheating at idle and dropping back down when moving sounds more like the fan is not working properly, to move air through the radiator at stops. I would look into that before replacing the thermostat over and over.
when my thermostat went bad it would heat up when not moving, the fan would not turn on cause it was not up to op temp and there was no air flowing through the radiatior. when i started to drive the temp went back down to the C line. i replaced the tstat and it works fine now
 


#4
when my thermostat went bad it would heat up when not moving, the fan would not turn on cause it was not up to op temp and there was no air flowing through the radiatior. when i started to drive the temp went back down to the C line. i replaced the tstat and it works fine now
The sheer fact that the OP has replaced this thermo 4 times would make me thing it is something else causing the issue.
 

Merlins Beard

*Beard not included
#5
that is true. mister OP, make sure your using 50/50, is there any corrosion on the old ones, not sure if this would have anything to do with it but is your water pump working good
 
#6
I'm probably the worst person regarding correct water/coolant ratio and I always use tap water. Chances are that isn't his problem. I would say i'm about 99% sure it's the fan.

If you're in doubt, hot wire the fan to be on 24/7 and i'm sure it won't ever overheat. When I was at the beach I smashed my skid plate into the fan, running without the fan it would do that. Heat up when i'm sitting but cool down when I'm driving and air is flowing through the radiator.

I highly doubt it's your thermostat.
 

Merlins Beard

*Beard not included
#7
I'm probably the worst person regarding correct water/coolant ratio and I always use tap water. Chances are that isn't his problem. I would say i'm about 99% sure it's the fan.

If you're in doubt, hot wire the fan to be on 24/7 and i'm sure it won't ever overheat. When I was at the beach I smashed my skid plate into the fan, running without the fan it would do that. Heat up when i'm sitting but cool down when I'm driving and air is flowing through the radiator.

I highly doubt it's your thermostat.
he doesnt have a problem with overheating because of his thermostat, he has had to replace it 4 times in 3 years
 

Merlins Beard

*Beard not included
#9
maybe the water pump?

i heard that if it overheats when stopped, that could be the problem as well. or is that all the time. someone wanna correct me if im wrong?
im thinkin the same thing. Gregab334, when was the last time you did the water pump, if ever
 
#10
Maybe he's not correctly checking the thermostat? I've rarely seen them needed replaced. And that it cools down when he drives really adds to the "Fan isn't working properly." idea. There shouldn't be anything that could FOUL a thermostat. Think about it, it's submerged in coolant it's entire life, having an incorrect ratio would not ruin it.

Could be a water pump.. but STILL, it cools when driving.
FAN.
 




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