Unusual Temp Readings

[Merritt07]

Hey guys, I have a question for you. Recently in the last few days, I've noticed my temperature gauge dipping down periodically from the nice middle point. Usually once the car is warmed up, it holds solid right in the middle, but the last 3 days or so, I've noticed that it will drop a bit and even dip between the 1/4th marker and the middle. I'm trying to piece together a pattern to determine when this happens. So far it appears whenever the car is slowing down using engine drag, such as when cruising on the highway and letting off the accelerator to slow down. The gauge will drop. Also, whenever I get off the highway, pull off the exit ramp the temp will drop.

A bit of history on the car. 62k miles, original cooling system as far as I know. Inspection 2 has not been completed yet, so likely coolant hasnt been flushed. I do drive my car fairly aggressively. I wouldnt say I beat the shit out of it though, I'm just not afraid to get up to 5.5k RPM when accelerating hard. This shouldnt be an issue.

Also note, the weather has been getting cooler. We are currently bouncing around in the 60's after being pretty steady 80's for a while, which followed a long 90's stretch. I dont see this being an issue, though. Everyone's cooling system warnings always have me paranoid, so I felt I should ask a few guys who know what I'm dealing with.


I appreciate your input.


Merritt

[WOLFN8TR]

Sounds like the Temp Sensor is bad.

[Newjack]

Sounds like the Temp Sensor is bad.

+1

I had a broken thermostat in my car before I redid the cooling system. So my temp would drop sometimes, very slightly. But it would take a long time for my car to get up to optimal temperature.

A faulty sensor would trigger the symptoms your car has. A busted thermostat wouldn't cause the drastic changes in temp your car is showing.

[danewilson77]

I say tstat is sticking open, and you have symptoms of impending tstat failure.

Sent from Williamsburg, VA USA

[GMATT]

What Dane said. I had same symptoms. Cooling system was fubar!

Gary

Sent from my fancy telephone!

[Newjack]

I say tstat is sticking open, and you have symptoms of impending tstat failure.

Sent from Williamsburg, VA USA

I had a thermostat that was stuck open, and it would never dip that low. It took a while for the car to come up to temp, and if I got cruising on the highway the temp would go down from the middle.

If the center of the needle is 12 o'clock, my needle never dropped below 11 o'clock.

I guess it could still be a bad tstat, but I would put my money on the sensor. Change it all out anyway.

[danewilson77]

Easy enough to start with sensor...$$$.

Then do tstat if sensor doesn't fix it.

Sent from Williamsburg, VA USA

[Merritt07]

I was thinking tstat myself, but the changes were so radical that I doubted if it were stuck full open, it would sit at 12 for a time. It also gets to temp at normal amount of time. A sensor seems appropriate. Downside is I'm tight on cash... I have a warranty that I paid for from the dealership when I purchased the car... I may be able to get them to do it. I also just found out that I'm rattling as well... I wonder if I can get them to do it all as it would only cost me a $100 if its covered. I was hoping to wait until I had the cash for the inspection 2 and get it all squared away. I hope I'm not hiding any demons in there. I better find out if the warranty covers all that work. o.O Anyway, yeah, pretty much confirms how I was feeling on it. Weird how it is fine one day, then the next, its having issues. I guess thats how the game is played.

Thanks again guys. I'll let you know what I find out.

[danewilson77]

I have a known good sensor I believe. I could send it down to you. No worry about any $$$. Then.....pull out old....plug hole with thumb, and install mine.

Done. Right as rain....Righty, right!

Sent from Williamsburg, VA USA

[Merritt07]

I would of course be more than happy at that offer. I'll PM you and we can discuss details. Thank you DW.

[Merritt07]

Alright, a big thanks to DW for helping me out. I changed out the temp sensor on Saturday and noticed a few things. First, when I pulled the old temp sensor out, I expected to see some coolant leak out... which wasn't the case. I compared the two sensors and I found the o-ring on mine was definitely shrunk down. It was the original green ring on their and there was a bit of a difference. It was clear that this was causing coolant to leak from the sensor. I popped my radiator cap off and sure enough, I was about 2 inches low on coolant. I topped her off and then bled any air out of the system. As of right now, I havent really noticed any issues since.

[danewilson77]

Alright, a big thanks to DW for helping me out. I changed out the temp sensor on Saturday and noticed a few things. First, when I pulled the old temp sensor out, I expected to see some coolant leak out... which wasn't the case. I compared the two sensors and I found the o-ring on mine was definitely shrunk down. It was the original green ring on their and there was a bit of a difference. It was clear that this was causing coolant to leak from the sensor. I popped my radiator cap off and sure enough, I was about 2 inches low on coolant. I topped her off and then bled any air out of the system. As of right now, I havent really noticed any issues since.

Good deal.

Sent from Williamsburg, VA USA