thermostat issues, gauge or no?

jsranger94 · #1 02-07-2016, 12:46 PM

not sure if this is the right thread to post under, but i have a 94 2.3L 4 cylinder automatic, and almost every time i start it, the thermostat gauge jumps up all the way past the red line hot, even though the engine itself is completely cold. im worried that the engine is being flooded with antifreeze because it thinks its overheating. the coolant level hasnt changed, so i dont think thats the case. the fan and all the belts seems to be working properly, and the engine/radiator are cool to the touch. after driving for a few minutes, the gauge goes back down to a normal reading, the heat and everything else works like it should. has anybody else experienced any problems like this, or have any ideas of what could be the problem, and any ideas on how to fix it?

GSF1200S · #2 02-07-2016, 01:28 PM

Quote:

Originally Posted by jsranger94

not sure if this is the right thread to post under, but i have a 94 2.3L 4 cylinder automatic, and almost every time i start it, the thermostat gauge jumps up all the way past the red line hot, even though the engine itself is completely cold. im worried that the engine is being flooded with antifreeze because it thinks its overheating. the coolant level hasnt changed, so i dont think thats the case. the fan and all the belts seems to be working properly, and the engine/radiator are cool to the touch. after driving for a few minutes, the gauge goes back down to a normal reading, the heat and everything else works like it should. has anybody else experienced any problems like this, or have any ideas of what could be the problem, and any ideas on how to fix it?

My 2.3l is a completely different design, but going based on experience, id say you either have a bad coolant temperature sensor or one of the wires connected to the temp sensor is shorted. I suppose air in the system is possible too.

The thermostat functions based on heat. No damage is being done

Basically the thermostat remains closed while the engine is cold. This traps the coolant in the engine forcing it to heat up quickly. Once it heats up to whatever the thermostat is rated at (190 in my case), the thermostat begins to open. It basically subtly opens and closes holding the temp at 190.

"Flooding the engine with antifreeze" isnt possible. Worst case the thermostat would be stuck open and the engine would run cold. This would kill gas mileage and possibly lead to carbon buildup over time (as the engine is constantly dumping fuel since cold engines arent as efficient), but no damage. A stuck thermostat also wouldnt cause your issue.

I would check the wires for a short first- you can manually follow them along to see for physical evidence of a short, or you can use a multimeter. If everything checks out, replace the coolant temperature sensor. If you still have an issue, bleed the cooling system.

Does your heater blow hot? Fwiw, I would avoid driving it until this is fixed. Its not that anything would be damaged with how it is now, but if you blew a hose or something youd never realize the engine was overheating.

Greasemonkey51 · #3 02-07-2016, 01:29 PM

That sounds like a bad sending unit. Cause it goes back to normal when it reaches temperature and it acts up when cold.

GSF1200S · #4 02-07-2016, 01:32 PM

Quote:

Originally Posted by jsranger94

...almost every time i start it...

I just noticed this. When it doesnt do it, does it work normally?

jsranger94 · #5 02-07-2016, 02:14 PM

Quote:

Originally Posted by GSF1200S

I just noticed this. When it doesnt do it, does it work normally?

yes, it works normally 3 out of 10 starts, the rest of the time it immediately jumps to hot. the heat works like it normally should, takes a few minutes to heat up, then its hot. also, i figured it was safe because although the temp gauge reads over heating, theres no check engine or check gauges light on. after about ten minutes of driving or less, the gauge reads right around the middle like it should

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im pretty new to working on my own vehicles, but i have common sense and a lot of electrical experience as well as experience working with my hands....watched video on changing brakes, took me 25 minutes to replace both my front brakes for the first time the other day

stateranger · #6 02-07-2016, 03:01 PM

Replace the sender first.

GSF1200S · #7 02-07-2016, 04:41 PM

Quote:

Originally Posted by jsranger94

yes, it works normally 3 out of 10 starts, the rest of the time it immediately jumps to hot. the heat works like it normally should, takes a few minutes to heat up, then its hot. also, i figured it was safe because although the temp gauge reads over heating, theres no check engine or check gauges light on. after about ten minutes of driving or less, the gauge reads right around the middle like it should

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im pretty new to working on my own vehicles, but i have common sense and a lot of electrical experience as well as experience working with my hands....watched video on changing brakes, took me 25 minutes to replace both my front brakes for the first time the other day

Ahh, i didnt read where it dropped to normal. Agree with everyone who suggests changing the coolant temp sensor straight away. Should be a pretty cheap and easy fix

Btw, your electrical experience will help a lot with fixing your rides. Especially nowadays- cars are electrical everywhere!

jsranger94 · #8 02-07-2016, 08:00 PM

thanks for all the advice, think i will definitely start with the sender, and go from there. hopefully thats all it is, as far as that goes.....now i just have to worry about the ignition acting weird once in a blue, new rotors/calipers, and a new exhaust.....haha....i still think it was a steal at a thousand bucks!