Have a bit of a weird issue/quirk going on...

I have an ultra gauge in the truck so I can monitor various things via the OBDii port. Engine temp is one of them. Since I have a 2001 it has a cylinder head temperature sensor rather than an engine coolant temp sensor. Temp will read higher. It reads about 220’ F which is normal.

What I can’t understand is depending on the drive. Normally coming home, then temp will drop to about 170’ F after I am more than half way home (40-minute drive). It will sit there for about 10 minutes or so then eventually come back up to normal temp at 220’F. I have replaced the electronic thermostat thinking that was the cause. Still proceeds to do the same finicky behavior. I changed out the cylinder head temp sensor yesterday and today still experience the drop, then eventually come back to temp. Coolant bottle isn’t low, and new degauss bottle cap replaced. Everything is OEM Motorcraft.

Not sure what else to check so looking for any advice. I have zero check engine lights/codes and zero pending codes. I will get CEL if I unplug the thermostat sensor so I know the parts are working correctly. Truck gets up to temp fine, blows heat. Blows cold air when AC is on. It never goes higher and it doesn't spike/overheat. No clue on this weird behavior however. This doesn't happen going to work for some reason, normally only coming home from work.

Thanks,
-Nigel

__________________
_____

2001 Ranger XLT 2.3L Auto: Bunch of misc mods.
Little lift: 4" Spindle Lift w/ 2" shackles and 2" oem blocks.OEM Ranger Sport Wheels: Tires=245x75x16

~NSG~

My best guess is that the load on the engine is lesser for that section of the drive. The harder the engine has to work - uphill, into the wind, coasting, accelerating, whatever changes speed or altitude, etc - the more fuel it will use, and the hotter the temperature. When it is not working so hard, it cools, and given ambient temperature and similar airflow over the radiator, the coolant temperature will change. Climb a hill, and the coolant temperature will rise, go down the other side, cool.
When ignorance is bliss, it's wise to stay dumb.
tom

I wish it were like that but going from 220 'F all the way to 170' F just seems really strange. It never did this the previous 5 years of having the truck so it makes me believe there is some type of electrical craziness happening. Just is annoying trying to track down a wire that might be slightly broken and is causing this intermittently...etc.

When this doesn't happen the temps will fluctuate maybe 10 degrees up/down during normal driving or going up / down hills..etc.

-Nigel

__________________
_____

2001 Ranger XLT 2.3L Auto: Bunch of misc mods.
Little lift: 4" Spindle Lift w/ 2" shackles and 2" oem blocks.OEM Ranger Sport Wheels: Tires=245x75x16

~NSG~

if it ain't broke don't fix it

roscoe

__________________
roscoe 0202
hi newb here truck 94 b4000 mazda aka ranger
truck is stock just runaround
have project bronco II
i'm 74 and retired
roscoe

If this behavior only happens with a particular 'drive cycle', i.e., coming home from work, then it must be load related. UNLESS. Unless you have wires that only jitter or shake loose, or voltage that only spikes or sags, or coolant flow that resists gravity and thermal conductivity, ON THE WAY HOME, but no where else...
Given all the above, figure out what items get fiddled with, shaken, jarred, have hot air blown on them, etc etc etc on the way home... that does not happen on the way to work...
I would suspect only one real thing differs, and that is shade. Do you park in the shade at home? Park in the sun at work? I suppose parking on a hill migh have effect too, but it would be difficult to test without parking 'backwards' to the normal way. I guess check environmentals.
tom

Yea it's super weird. I do park in the shade when I am at my house under a tree and the truck points down hill slightly. At work it's in the sun for 8 hours on level ground. I will note that the the drive to/from work is more hilly. As compared to my drive before where it was mainly flat highway. I took out the harness that is by the intake manifold yesterday just to inspect. All wires seem to be in tact and I even put dielectric grease in the connector but there were zero signs of corrosion.

I will note that on the way home I will turn the AC on. Something yesterday as well. I got almost all the way home until I turned the max ac on and then about 10 minutes later the temp dropped. Which makes me wonder if that is related at all some how. I don't even remember this happening ever but I also didn't have an ultragauge. I would have probably noticed the dash gauge drop down so low but I know I don't have the AC on going to work since it's still very cool in the morning but in the afternoon when it's almost 100 I turn it on.

-Nigel

__________________
_____

2001 Ranger XLT 2.3L Auto: Bunch of misc mods.
Little lift: 4" Spindle Lift w/ 2" shackles and 2" oem blocks.OEM Ranger Sport Wheels: Tires=245x75x16

~NSG~

looks like you're gonna have to freeze your self with the AC on next time you go to work!!! There's no other way!
lol, just kidding. i'm wondering if the thermostat location has anything to do with it. isn't the 2.3 Duratec t-stat in a weird spot, on the lower hose instead of the upper hose?

----------

is yours the electric thermostat?

__________________
1999 xlt 2.5l 5-speed Supercab 159k
83 diesel 2.2l na
06 F250 6.0l psd
{click for lol}

So this time around I drove without the AC thinking that perhaps it might not do it.

Got past the usual spot where I drive home where it normally happens by about a couple mins, more down the highway. Sure enough I see the temp start dropping. Goes all the way to 170-180' F until I get home. Pop the hood and start feeling the hoses. Both upper and lower rad hoses are hot. Giggle the wires around and nothing changes. I open up the degaus bottle and hear a small hiss noise but the coolant doesn't raise up at all. Which seems odd considering if it was pressurized it should raise up quite a lot. Put the cap back on.

Shut the truck off, waited 5 seconds then started it back. Temp starts to go back to 220'F.

The 2.3 duratec has the t-stat on the bottom side of the engine in a way. Very close to the lower radiator hose. Mine is in fact the $120 electronic thermostat. This was the first thing I thought of when it started acting up so I replaced it with a new OEM motorcraft one, yet it still does it. Super strange.

I'm wondering why when I unscrewed the rad cap there was not really any pressure... makes me wonder if that has something to do with it? When the truck is at normal temp and I unscrew the cap the coolant starts raising quite fast and if I don't screw it on quickly it would come out the top. This case that wasn't the situation at all.

-Nigel

__________________
_____

2001 Ranger XLT 2.3L Auto: Bunch of misc mods.
Little lift: 4" Spindle Lift w/ 2" shackles and 2" oem blocks.OEM Ranger Sport Wheels: Tires=245x75x16

~NSG~

I don’t have AC and mine has done the temperature sway ever since I got a new thermostat.... how ever I don’t have the huevos to open a hot radiator cap so i don’t have the answer on that. But I’ve chocked it up to good ole ‘merican engineerin.


Sent from my iPhone using Tapatalk

__________________
4-cylinder squealin tires like a bag o' pigs! Yeeehaww

Maybe you have an air pocket?

UPDATED:

Talked with several ford techs and explained to them exactly what was happening. They stated this is normal. Depending on load and temp the computer will automatically trigger this type of cooling.

I told them it really only happens on long grades where there is quite a bit of load throughout the grade of the hill. I took my truck to my parents house in PA which is through the mountains. It did this several times throughout the trip and all for a timed period of time. IE: After going up a long grade it would drop the temp to 180* then stay there for 7 minutes. Sometimes less if I was then going back down the hill and there was zero load on the engine.

After showing them what I had written down each time they said this was by design.

So that's cool then. Which makes sense I guess considering my last commute to work was on flat highway and now I am going up and down long graded hills...etc.

So if this happens to you it's normal, don't freak out. Note that there was no hardware failures, sensors, no air, etc. Everything is working as it should.

-Nigel

__________________
_____

2001 Ranger XLT 2.3L Auto: Bunch of misc mods.
Little lift: 4" Spindle Lift w/ 2" shackles and 2" oem blocks.OEM Ranger Sport Wheels: Tires=245x75x16

~NSG~

Not sure how this happens if you have a traditional thermostat...?

it's got a little heater element in the t-stat assembly i think.

__________________
1999 xlt 2.5l 5-speed Supercab 159k
83 diesel 2.2l na
06 F250 6.0l psd
{click for lol}

If it's and after market electro-stat (), and it came with a traditional one then that seems a good starting point to trouble shoot...

i believe the first couple years of the 2.3 duratec came stock with that crazy little assembly. Then i guess they realized it sucked and quit putting it on lol, kinda like the intake runners

__________________
1999 xlt 2.5l 5-speed Supercab 159k
83 diesel 2.2l na
06 F250 6.0l psd
{click for lol}