Fluctuating temperature gauge



JohnS.

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#1
I was driving my car today and noticed the temperature gauge wouldn't go past the the top of the 2 bottom bars. It fluctuated up and down (depending on if I was on the gas or on hills) a few millimeters. I changed the thermostat within the last 30k so I'm ruling that out unless it really went bad that fast (it's only been replaced once since the car was bought new). I'm pretty sure the fan kicks in though I'll check tomorrow. Also, I was driving with the heat on full and blower on. The radiator fluid was drained out of the bottom of the radiator drain plug then refilled roughly 3-5k ago when I did my timing belt. The radiator and fan are still original AFAIK.

Anyone have any ideas as to where I should start looking? Thanks in advance.
 


JohnS.

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#3
I thought that at first but how would air magically appear in the coolant 3-5k+ miles after it was flushed and refilled? I haven't touched my radiator cap since I filled the fluid.
 


Kensai

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#4
That sounds normal since you had the heater on, unless your car actually started overheating.
 

JohnS.

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#5
I've been using the heat for the past several weeks and it's never done this until now. The temp gauge will normally go up about 1/3 of the way and stop as usual. It didn't even make it past the bottom bar today and it was definitely warmed up.
 

JohnS.

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#6
Well just a quick update... I had bought a new IACV gasket earlier in the week so I took my IACV off, cleaned it out (again), put the new gasket on, put the IACV back on, took my radiator cap off, and started the car and let it warm up until the radiator fan kicked on a couple of times. The gauge went up normal, only a couple of air bubbles came out of the top, I topped off the fluid after turning the car off....

So it's normal for now. Until next time.... Damn old cars and their problems. It could also be my instrumental cluster because last week, randomly on one morning, one of the bulbs above my speedo was out. Then the next day it was back to working. It only happened once.
 

JohnS.

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#7
Back to not working this morning... I have ~6.2 mile (city) drive to work and usually the car is fully warmed up by 2 miles and the heat is normally coming out hot as can be by then as well. The temperature needle was JUST starting to move by the time I got to work and the heat was just mediocre warm. I'm starting to think I need a new thermostat but it's only been approximately 30k miles since I got my last one.

Any input?
 

JohnS.

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#9
Where is said sensor located? Is there any way to test it or do you normally just replace it?
 

JohnS.

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#11
It sure SOUNDS like a bad engine thermostat. I agree, they ought to last more than 30K. Maybe this one didn't?
It is possible, for sure. But I don't understand why it would if my previous one lasted ~200k. Regardless, a local dealership had 1 and only 1 in stock so I told them to put my name on it and that I would pick it up later today after I get out of work. For $35, why not? I'm more of a replace-things-before-diagnosing-everything kind of guy lol. The less work I have to do, the happier I am. I hate troubleshooting. I would rather just replace it than sit there and try to figure okay this is bad, that's good, this is good, that's good, but this is bad, so that means that has to be good.... Yeah no thanks.
 

nathan_carmona

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#12
Where is said sensor located? Is there any way to test it or do you normally just replace it?
Ill try to take a pic on my car tonight. Idk if you can test em. You can easily test the thermostat though. Turn the car on, let it idle for a while or drivd it till it should be hot and feel the upper rad hose (it should be hot so use caution) if its easy to squeeze and doesn't feel like there's anything in it, your thermostat is stuck. If its kinda solid and there's liquid running through it, chances are, you've got a bad stat.

Sent from my SPH-D700 using Tapatalk
 

JohnS.

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#13
I finally got around to changing my thermostat today. Upon looking at it after pulling the housing off, it looked okay. I yanked at it, and the inner gasket crumbled and this is what it ended up looking like:







Changed it out and now my car seems to warm up much faster and needle works perfectly. I lost a lot of coolant so I left the cap off while the car warmed up and got a ton of bubbles after the radiator fan kicked on the first time.

:thumbs up. I love it when I fix my car and everything works afterwards.
 




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