Cooling system and ECT reading question

[95opal]

the ECT values seemed consistent with the expected results when i tested them.




the cap is brand new FWIW, and i replaced all the hoses a year or so ago when one was cracking.

yeah, I understand that honestly but the main thing for me is that my car *doesn't* run at 208 or 200 or even 190. if I run the AC at all, it stays at 175 or lower (typically 155-160) even after long drives.

if I don't run the AC, it gets really hot (on the gauge) before it even attempts to cool itself lol.

I wish I had some way to see inside and confirm the sensor has coolant flowing on it and not an air bubble or something.

I tested my dad's car (admittedly it is newer), an 03 grand marquis with a 4.6L. watching the ECT reading on that, it went from ambient to right around 195-200 within 5 minutes very smoothly and stayed there, even with the AC running the entire time. its just weird behavior seeing mine be so slow to warm up allegedly and never hitting those sweet spots

I do appreciate everyone's assistance though, even though I'm feeling frustrated cause it feels like a "non-problem" problem

When you turn on the A/C your turning on the high speed fan. With the A/C off the low speed fan won't engage until about 208 210.

 

[MechaZao]

yea, thanks guys. I've still not quite sorted this out. I went on a couple trips out of town this weekend, 2+ hour drives on the highway, and the ECT never read higher than 175 both times (163.8 on the trip up, 175 on the trip back). that is with the AC on, I never really drive with it off. from what I know about cars, the ECT should be reading roughly normal operating temperature no matter what state the fan is in - so 200ish? but it never does unless I let it sit there idling for a long time with no AC and then the gauge goes up really high lol

i'm going to try changing the thermostat again tomorrow and putting a fresh rubber ring on it instead of reusing the old one like before. I'm wondering if coolant is getting past the thermostat internally regardless of it opening, and maybe that's the issue.

I'll probably do a coolant flush in the next couple weeks just to rule out any blockages as well.

another possibility is that I have some sort of head gasket leak in the vicinity of the ECT and its pushing air and gases up into that elbow - but I don't have any other signs of a blown HG as far as I know.

I've got some other issues/quirks about the car too that I'm gonna make another post on in a sec.

I'll keep ya'll updated with this particular issue when I learn more

 

[MechaZao]

hey folks, just an update. I never did figure out why the ECT was reading so low, but I found a solution that works for my car.

I swapped the Sender and Sensor position on the car, and lengthened the wiring to make it fit. now the ECT Sensor reads a much more accurate and faster-moving temp, and the gauge still works as I'd expect it to, though it takes a fair bit longer to get to a normal level. the fan comes on much more often now with the AC off, and on a steady drive the temps hang out around 185 while moving. much better.

as for theories on the reasoning, my money is on just some poor coolant flow or something to that effect. I still plan on doing a coolant flush when I get some downtime for that.

its not the way the factory designed it, but if it works, it works.

still no heat, but I'm 90% sure at this point that i've got a break or obstruction in the blend door so I don't feel like doing all that.

thanks for all the help!

 

[07GtS197]

For an internal combustion engine to run at its peak, it should be around 200*. Running too cool is not good either.

 

[95opal]

hey folks, just an update. I never did figure out why the ECT was reading so low, but I found a solution that works for my car.

I swapped the Sender and Sensor position on the car, and lengthened the wiring to make it fit. now the ECT Sensor reads a much more accurate and faster-moving temp, and the gauge still works as I'd expect it to, though it takes a fair bit longer to get to a normal level. the fan comes on much more often now with the AC off, and on a steady drive the temps hang out around 185 while moving. much better.

as for theories on the reasoning, my money is on just some poor coolant flow or something to that effect. I still plan on doing a coolant flush when I get some downtime for that.

its not the way the factory designed it, but if it works, it works.

still no heat, but I'm 90% sure at this point that i've got a break or obstruction in the blend door so I don't feel like doing all that.

thanks for all the help!

I have to ask was the ECT in its factory location or in another bung?