white89gt

Maybe I'm thinking of the older motors (5.0 and 5.8) .... but I think these have a sensor for the gauge, and a sensor for the ECU.

I also wonder about the steam you are seeing. I think you may want to get a hydrocarbon test kit if the conditions continue.

Keep us posted.

BareBonesXL

I looked a little deeper and even my 03 engine uses a "sender" for the gauge and a "sensor" for the PCM. Two components in the engine that indicate temperature, very common. Who knows what the PCM actually uses to activate the fail-safe mode (that's what Ford calls it). The sensor is supposed to be used for engine control, maybe the sender is monitored for fail-safe mode.

Or it might just be hot gases.

white89gt

Potato / Patato. Each has its purpose, whatever terminology it has, lol.

BareBonesXL

I think that they use the two words to distinguish between the gauge device and the computer device. Nissan does the same thing, I come from Nissan world. I was just pointing out that you were right, probably. Unless Ford used the gauge reading to go in to fail-safe.

Could be also that he never went in to fail-safe and the engine ran poorly because the PCM was getting bad temperature readings. Hotter = leaner. From what I've read there's a dash light that says "fail-safe mode" when it happens, or the CEL comes on.

Just glad it's not my problem. Looks interesting though.

jstockert

The 97 f150 uses 2 coolant sensors. One on top of the manifold just behind the bracket that holds the upper hose. The other is on the driver side head, under intake in the area of 5 spark plug. Except under the manifold. Both have different functions, but not sure which one.

JCR 56

I would do a hydrocarbon test on the coolant and check for exhaust gases.

thelaibon

Well, bad news, despite properly burping yesterday, I overheated this morning - same symptoms - CEL on, temp gauge instantly to the max, turn off engine, wait 10 seconds, turn on engine, temp back to normal and driving fine.

I'm gonna try burping again today but after that, all other hydrocarbon testing, et al, is well beyond me and I'd have to bring to my mechanic.

white89gt

You can get a kit at Autozone. It's really simple to do....

Aragorn

I'll have to try this next time. There is a super hilly and rough road not too far from my house, hit it going 35 (the speed limit) and running the heater and so far I've not had problems bleeding the truck but this would be a lot easier. Have to run that road at least twice to get it bled completely.

thelaibon

I'll consider this as my next step. Altho it's tantamount to a doomsday test, lol Thanks!

ALL: I stopped by my friendly mechanic (a sane person would have done this sooner), and he spent 5 min looking at it, and he is pretty sure it's not actually overheating. He said: if the radiator hoses don't get overly hot, you don't see or smell smoke or fluid, then it prob isn't overheating (simple logic). He advised me to change the cooling sensor, and perhaps the 2nd sensor as well, as mentioned above by several of you.

My mechanic showed me the location of both sensors, both were slightly on passenger side of engine (near the front, near-center), and were only 6 inches apart or so. I went ahead and bought new ones for good measure - only $32 total - I will change those today and re-burp. Mechanic also advised to let it run with the cap off for a good 30-60 min to let all air out just in case there's more. He said let it spill over the top. I guess, tho, I should keep an eye that it doesn't run dry from overspilling.