I have a 88 F250 with the 7.3 and the reading on the temp gauge never goes into the normal range. I live in Canada so we get some pretty cold winter temps, an average day it will be anywhere from -4°F to -22°F (-20°C to -30°C) Is it possible for the gauge to not work properly but still move? I took the the connection off both probes (sending unit and temp light) and when grounded to block then gauge went hot) I am currently running a winter cover on my truck. I get decent heat in the cab once the truck warms up. So if the temp gauge works then maybe my thermostat is not working correctly or it could just be a colder thermostat.

How difficult is it to change the thermostat out of the truck and is the temp gauge is good? Thanks!

 

Bgab,

The stock gauges are suspect at best. It is best to install an aftermarket coolant temp gauge if you are unsure of your dash gauge working correctly. For the record, the 7.3 t-stat location is not an easy access change. There is a lot of component removal to access it. Not the best engineering!

Mac.

 

The gauges on these rigs are little more the idiot lights. There really inaccurate and don't really show true values for anything. Your best bet would be to get yourself and after market gauge and go from there. As for the thermostat its not really a difficult job but be sure to get a genuine motor craft or international part pretty much all the after market ones are garbage.

 

If you don't know the history of the thermostat it might be a good idea to replace it. My '85 ran cold since I got it when I got around to replacing the thermostat this is what I found:




The PO used a cheap-o replacement which broke open and allowed the coolant to flow by it freely.

 

Well I bought the truck used and there is a thermostat in the glove box that says 195 (which is stock) So what I am thinking is someone put a cooler thermostat in and maybe the one he put in was not a motorcraft stat. I think I will swap the one that is in the glove box.

 

Check it out carefully, just because it's in the glove-box doesn't mean it's any good or even out of that truck. Stock is 192 so there's a red flag right there.

 

Here you go:

THERMOSTAT REPLACEMENT 101 Tech PicTutorial

 

I for one have never had trouble with factory guages, that being said, when the sending unit goes out or is going out, the guage will read low. So its your guess whether it would be the t-stat or sending unit. After it "warms up" can you keep your hand on the radiator tank, does it feel like 180-190 degrees?

 

Yes the thermostat says 192 not 195 (the one in the glove box) and I have felt the upper rad hose after the truck has run and I think the hose is not as hot as it should be. So next week sometime when it warms up a little outside, I will swap them out because I just think the previous owner put a cooler stat in for the summer months but then never put the stock one back in?

 

Alot of people mistakenly think that a cooler t-stat is better... that is of course not true typically

 

The Temp gauge is far better then the Oil pressure gauge ...

Neither have numbers to correlate with anything ... Not that it really matters as long as all the proper components are installed and it's runs in the proper range! What do ya need a number for!
Because we want to know if it's 200 or 250 degrees ... Not 'N' or 'o' or ...

The temp gauge is not a glorified idiot light, it does change according to the temp. What that temp is at said point ... Who knows!

On the other hand, The oil pressure gauge is no more then an idiot light pure and simple ... it's either above 5lbs or not! (I believe it's 5 pounds)

Moral of the story, if only one gauge is possible ... Make it an oil pressure gauge!

[hijack]
I run 3 additional permanent mounted gauges, Boost, Pyro and Oil Pressure!

However they are about to be replaced with an in dash version of the Micro Controller I've developed that's currently setting on the hump in front of the shifter with the display setting on the dash that has:
22 D/A IO ports for Sensors and Controllers (ie: N75 valve, Fuel Pump, Water temp, Oil Pressure/Temp, Ambient Air Temp ... Pretty much whatever you want)
8 Type K Inputs (8 was as easy as one, No cost diff ... so why not!)
2 VRS Inputs (For Tach and VSS - $85 bux for each chip! ... Want to add two more for CPS, $$$ add up and the MFG tells me they are working on a 4 port for about the same price, they released a two port after I started this proj.)
8 Digital Inputs for mode buttons/switches.
Micro SD for full logging capabilities. (currently 100 times a second)
USB Port for downloading logs, monitoring live, Uploading new code.
More on this in my own thread when I get around to documenting it ...

I do have 7 additional temporary gauges I'm about to wire tie under dash for testing. Water Temp, Drive Pressure, Intake vacuum (pre Turbo), 2 Air Temps, 2 Boost for Pre IC and Post IC.
[/highjack]

-Enjoy
fh : )_~

 

Even worse some guys think it's a good idea to remove the thermostat altogether. Another good reason to check.