My 2002 2.3L runs fine. No overheating anymore. Dash temp gauge stays slightly below half. ODBII reports temp range from 235-255 at any given moment since I have owned this truck and everyone says these engines are designed to run hot.

But yesterday, out of the blue, the dash temp gauge dropped to cold. I quickly connected my ODBII monitor and it showed the temp at 190 (where I would expect it to be in a normal car). No heater or AC was on.

I visited family for a few minutes and turned the car off. When I turned it back on again everything was normal. 15 minutes into the drive home it happened again.

I noticed no other symptoms. Everything run very well. No engine lights.

Note; in November I was having major overheating problems and ended up completely replacing my cooling system. I mean completely. Every hose and pipe, rubber and metal, radiator, water pump, both fans, degus bottle and lines. Yes, I even replaced the octopus stupid pipe that runs behind the engine and has to flimsy plastic T-connector that always fails and costs $800 for Ford to replace. I did my valve cover gaskets at the same time so I already tore the top of the 2.3 off. I did not do anything to the heater core but heater and AC works great.

During my cooling system changes adventure I had replaced my Thermostat four times, yes it's the electronically heated one.

I'm using that expensive Ford recommended gold coolant too.

I thought I was finally done with my coolant issues!!!!?

Anyone smarter then me have any advise besides suggesting that I drive the truck off a cliff? BTW: There are no cliffs in NE Florida.

Check the connector on the sensor that runs the guage if its loose or has broken clips that hold it it can give faulty readings. If its ok , try a new sensor that runs the guage. After that i would troubleshoot the thermostat. After this i have plenty of cliffs here in ky... Lol... Let us know how it goes.

Get that godawful electronically assisted RT-1157 190F thermostat out of there and put in the Gates 180F thermostat. Zip tie your old thermostat under the hood and plug in the connector so the CEL won't be triggered.

Best decision I made for my truck. For me, everything's been smooth sailing, temperature wise, since doing that a couple years ago.

EDIT: I also agree with 07Vulcan's advice, the reading could be faulty due to a failing Coolant Temp Sending Unit. I had mine replaced when I first got my truck, I think it was located in a hard to access spot down by the firewall. However the fact that your temp is occasionally reading 190F, which is exactly what the RT-1157 is specified for, makes me think it could be thermostat related and not due to failing Coolant Temperature Sending Unit. Not sure though...

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Harbor_Handed, If I am correct I read that you were involved in a similar situation back in 2016. That post being so old I couldn't reply to it. So I started this new thread.

If I am correct, and based on your recommendation, I assume that you have replaced your TS with the Gates 180F back in 2016/17? Have you been running that Gates TS since? Any more TS replacements?

I have been leaning towards doing this for some time. I plan to use a resistor (as recommended by others) rather the zip tying off the old TS under the hood. But before I do that, I wanted to ask first if you have had any side issues whatso ever? Long trip issues? Fluctuating dash gauge? Any readings from an ODBII monitor that show the engine still hovering between 235-255 degrees (that's 2.3l normal apparently). Any issues with the engine at all running at the colder 190 temps (normal for the rest of the world). Does your dash gauge show cold with the Gates or is it in the mid point position?

Thanks for the reply.

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Ty for the advice 07Vulcan. I'll keep the folks involved. If I go the route of the Gate TS recommended by Harbor_Handed, I'll put together instructions and photos for anyone else having this issue.

Cheers!

I replaced my OEM thermostat with the Gates 34044 180F Thermostat 2 years ago, and my gauge now stops right below the half way mark and stays put there at all times, never wavering at all. I have nothing negative at all to say about it. I drove across the country last year, driving hundreds of miles a day over mountains and prairies and even up the Donner Pass, and the needle never wavered. I only have love, love, love for my Gates thermostat.

Please note that I edited my other post to you in this thread, adding some info about Coolant Temp Sending Unit.

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One last question. Have you (or anyone else) experienced the temp with the stock type TS running always between 235-255 degrees?

Thank you Sir. I will update this post when I replace my TS with the gate.

My 2.3 dtech runs consistently at 190-195 (Read via a scanner). Thats just under the halfway mark on the instrument cluster. However mine does not and never did have the electronic t-stat. 255 is way too freaking hot.

When I was having overheating issues, it always overheated at 265 degrees. I've replaced many TS in my life and I have never seen anything like this 2.3L. Even 235 is way too hot. The other weird thing is that I struggled to understand how the ODB2 showed 255 and then drops to 245 like within seconds depending what the car was doing. That lead me to believe perhaps my ODB2 was reading the CHT. How can you have a 10-15 degree drop in seconds, of course, it started to make sense when cool water from the radiator is permit to circulate. But wow 235? It should never go over 215-220. Well, I'm sold the concept of the Gates 34044 180 TS. Gonna do it!

I don't have any OBDII/monitoring on my truck, just my cluster temp gauge.

My experience with the OEM electronically assisted thermostats is that when I bought my truck, the thermostat was stuck open so the truck never would reach temp. So I ordered the OEM replacement and put it in there, and I would then witness the temp needle on hot days start to creep up to the halfway mark and a little beyond, right before my very eyes, which made me very uneasy. In my experience, the needle should stay stock still, right below the halfway mark.

I then began to research the issue, and discovered a lot of people saying the electronically assisted thermostats are crappy. The regular wax thermostats are brilliant, simple and elegant inventions - why did someone try to reinvent the wheel by adding an electronic heating element or whatever? So I bought a Gates thermostat and it's been brilliant. MPGs are wonderful too. No issues anymore.

I don't know what specific temps my coolant was climbing to during those moments the needle would creep up a little, but very high temps can't be good. I know higher heat can cause the head to warp, and make plastic components turn brittle...Eeek.

Ma'am...Girls can turn wrenches too, you know. lol

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Like "Robin Leech" could not have been more relevant in my careless conclusion . I bow humbly and beg forgiveness! Girls turning wrenches is so hot! Thank you for your help Robin.

No worries.
I just like to let people know every now and then that even though I'm "one of the guys" on here...I'm not actually one of the guys. lol

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Only thing I can add is to check the coolant level to be sure there are no air bubbles in the system. Air will not make the sensors work properly as I understand. Second would be to find which sensor is producing the number, the 235, as there are at least two temperature devices, a sender and a sensor. One for the gauge, the second for the computer. For all I know, there could be a CHT - cylinder head temperature - sensor also.
tom