7.3 Powerstroke heat

[Ouachita]

I bought a 1999 Ford this past spring. I'm just now learning that it doesn't blow hot air when I crank the heater up.

Is this typical for the series? I know this truck has a larger aftermarket radiator and fan. It was a fleet truck built for long hauls. Maybe need a warmer thermostat?

I need more heat because wife won't go check cows with me anymore. I hate opening gates.

 

[chevytaHOE5674]

Thermostat probably failed open. Fairly typical issue with a truck that old.

Get a new thermostat from the ford dealership. When the ford one fails it typically fails open (ie low heat), most of the others fail closed (ie overheating).

 

[jltrent]

For the short term just put a piece of carboard partially in front of the radiator until the new thermostat is installed. A very inexpensive common item to fix and try to get OEM.

 

[chevytaHOE5674]

One of my 7.3s thermostats stuck open in the winter. Even with the radiator 100% covered the coolant wouldn't get warmer than 140 degrees while driving, and 160 degrees while plowing snow or hauling a loaded trailer. This yields no cab heat, reduced power, and worse fuel economy.

Motorcraft t-stat is 192 degrees and the part numbers are F6TZ-8575-EA or RT-1201

 

[SmokinM]

Ditto on the thermostat. I have had that happen to mine. Also had to replace the blower motor. I assume the truck temp gauge is reading cold? If so most likely your thermostat. Also it just takes awhile for those trucks to warm up. Like on a 30 degree morning idling around the farm it may not reach temp for maybe an hour. I typically let mine warm up about 30 min. and not uncommon for them to still need a mile or two on the road to actually reach temp.

They are fantastic trucks but puttzing around on the farm is not where they shine. They are not jump in and go kind of motors. They like to run and will for days on end but off and on start, stop is pretty hard on them. Mine will be left idling anytime I will be less than an hour stopped. Many, many days it has run 24 hrs. or more continuous and not uncommon at all to start it at 5-6 a.m and turn it off at 6 p.m.

 

[chevytaHOE5674]

With a correctly working thermostat both my 7.3 trucks will come up to full temp within 10-15min of idling in the winter (temps below 15 degrees). Usually let either of them warm up just long enough for the idle to smooth out and then start driving.

I dont typically leave my trucks idle for any longer than a few minutes. Idling just burns expensive diesel fuel and puts hours on expensive oil.

 

[GoWyo]

Plug in the block heater if it will be less than 30* F and they will start right up and warm up quickly.

 

[cfpinz]

The thermometer has been stuck open in my 97 7.3 for 2 or 3 years now, new one has been sitting on the shelf in shop for a little over a year now. Little to no heat but I haven't noticed any change in fuel economy - and I've checked mileage every tank for the past 12 years.

 

[Ouachita]

Plug in the block heater if it will be less than 30* F and they will start right up and warm up quickly.

I do plug in the block heater when it's going to be below freezing, but starting hasn't been a problem.
It doesn't matter how long the truck has been running, nor working. Although the fan blows fine, it only blows air that is just barely warm enough for her to thaw her fingers out after opening the gates.

That temp gauge is about as warm as it gets. I'll put a new thermostat in it and see what happens.

 

[jltrent]

I do plug in the block heater when it's going to be below freezing, but starting hasn't been a problem.
It doesn't matter how long the truck has been running, nor working. Although the fan blows fine, it only blows air that is just barely warm enough for her to thaw her fingers out after opening the gates.

That temp gauge is about as warm as it gets. I'll put a new thermostat in it and see what happens.
View attachment 37502

No expert, but I believe the Temp gauge will come on up about halfway when the thermostat is working properly or mine does. and will put out warmer air in the cab.

 

[Ouachita]

No expert, but I believe the Temp gauge will come on up about halfway when the thermostat is working properly or mine does. and will put out warmer air in the cab.

Okay, that makes sense. That needle position is as high as it ever gets, even in summertime, and it will only get that warm after some extended idling. As soon as I start getting some wind into the radiator, that needle moves down about half more. Like this. I'm certain that changing the thermostat is first order of business, and won't harm a thing.

Hoping it works, because wife said she's in the market for a new jar opener iffin I don't get some heat in that damn truck!

Instead of cinnamon and spice, I think the doctor must've sprinkled her arse with garlic and vinegar.

 

[Down in Dixie]

Thermostat on mine hangs open. Not that bad but never reaches operating temp in cold weather. Guess it's a common problem.

 

[SmokinM]

Yep you need a new thermostat. Needle should be about a 1/4" up in that operating range bar when at temp. The heat works good once they warm up the right way. FWIW I would put an OEM thermostat and gasket in it. Aftermarkets seem to not do right for whatever reason.