Heater gets warm then colder with Temp Gauge

[jimbo231]

My mom's 98 explorer was having problems with the temp gauge. It would go up as the car warmed up but wouldnt go up to where it should then slowly go back down and repeat as we drove. I thought it was the gauge but when the heats on the heat gets warmer then colder along with the gauge. I have know idea what could cause this....any ideas?

 

[adamtrippin]

Make sure coolant is full and not dirty.

 

[adamtrippin]

At normal operating temps ur resivoir should be up to the hot mark.

 

[Convict1997]

Sounds to me like you might have a thermostat stuck open.

 

[jimbo231]

Still have the problem....wouldn't a bad thermostat only cause the heat to warm up slower but still be hot after a while?

 

[my98nnj]

Replace the thermostat, they do tend to get weak as they age and cant control the engine coolant temperature correctly.

 

[Convict1997]

Still have the problem....wouldn't a bad thermostat only cause the heat to warm up slower but still be hot after a while?

Not necessarily. If the thermostat is stuck open, you'll constantly be cycling coolant through the heater core but most if it won't have been heated because it never spent any time in the motor. I guess, eventually, you could end up heating all of the coolant in the system, since it won't be spending any time in the radiator cooling off.

It's been almost a year. Check (or just replace) the thermostat already! lol.

 

[JimMadsen]

A tstat is somewhere around 5 bucks! Whenever I am in the area of it, I get it changed. I changed it one august and in december had to do the water pump, changed it again then.

On that note, I assume your pump is the same age as the tstat, you have to get it off to replace the tstat, might as well put a new one on. Wish I did oh and the hoses in the area too may be a good idea.

 

[Convict1997]

A tstat is somewhere around 5 bucks! Whenever I am in the area of it, I get it changed. I changed it one august and in december had to do the water pump, changed it again then.

On that note, I assume your pump is the same age as the tstat, you have to get it off to replace the tstat, might as well put a new one on. Wish I did oh and the hoses in the area too may be a good idea.

Um.....no you don't. The thermostat and the water pump are completely separate.

 

[JimMadsen]

Yes, but if the system is drained, you might as well change it. At least that is my preference.

 

[Convict1997]

Seems like replacing the water pump just because you've drained the coolant is creating a lot of unnecessary work. That's kind of like saying, "You've drained the oil. Might as well put in a new motor." I can understand wanting to save having to remove a pump twice and reinstalling a new one when the old one has to be taken off, even if it isn't presenting any problems. But, removing the pump just to do it when there are no symptoms that there is a problem with the pump is really just a waste.

 

[bill06447]

You'd definitely want to do a thermostat and hoses when doing a water pump, but a water pump just because? Ummm, no thanks. Agree with other posters, nothing good is going to come out of that.

Bill