[THERMOSTAT RECOMMENDATION] 1994 7.3L IDI N/A

Hey there folks,

I am looking to change out my thermostat and have seen a fair amount of debate on the recommended thermostat to install. The reason I am wanting to change it out is because I think my temperature is reading low. When casually driving around town, my temperature sits right at the letter "N" position on "NORMAL". However, when climbing up these front range Colorado mountain grades at high RPMs for extended lengths of time at speeds not much higher than 45 MPH, I have never seen my temperature gauge much past the center of the letters "R" and "M". At 12,000 lbs I'd expect to be running quite a bit hotter. Do these readings seem normal to y'all?




Thanks for any help,
Andrew

I have two reactions to what you've said above.

Use ONLY a true Motorcraft thermostat. It's a proven fact that no other brand works well or even decently.

The temp gauge in our trucks is nothing more than a moving idiot light. It is not to be trusted if you value your engine. Compare the cost of a true after market gauge to the cost of a new engine. There is a clear winner.

O'Reilly carries the proper Motorcraft thermostat with the gasket: https://www.oreillyauto.com/detail/...-1985-ford-e-350-econoline?q=thermostat&pos=1

If you want something low priced in the way of a proper gauge, I recommend this one because it shows 240 as a major marker: https://www.iequus.com/8242.html

It comes with the adapters that fit IDIs so it comes with everything except wire to run for the backlight. That's what I run on my RV. It's $30 from O'Reilly too, and it's often kept in stock in stores: https://www.oreillyauto.com/detail/...-1985-ford-e-350-econoline?q=equus+8242&pos=0

Second on the above, only use motorcraft/Ford or the international equivalent part numbers. All the part numbers are in the IDI quick reference threads at the top of forum headers.

Your fan clutch could be not working very well, do you hear a significant change in engine noise as the engine gets hot and the clutch engages? Usually you can hear the fan roaring when you first start driving when the engine is cold and then it goes quiet until it gets hot and then you can hear it engage again. If you’re not hearing it at cold start for the first minute or two of driving or when it starts to get hot, then that would be the first item to address.

Also make sure that the connections to your sending units are clean and tight. There’s one in the top of the block on the driver side of the injection pump, that’s the gauge one, then on the outside of the driver side cylinder head is the one for the over temp warning light. Then check the engine wiring harness connector for loose/melted/dirty pins. Those are the most common culprits for unusual gauge readings.

When you change your thermostat, make sure the bypass in the housing is clear to let the air bubbles circulate out before the thermostat opens. At the mating surface on the housing side, there is a hollow phenolic plug that holds a check ball in the bypass passage. If yours is still in place, don’t dig at it too much or the check ball will fall out.

search this thread for the thermostat and gasket part number options;

It is normal for the factory gauge to move a couple of letters on steep grades.

As stated above the guage is not accurate, install a aftermarket gauge so you have real visibility to your water temp. Do the oil pressure and voltage while you at it! If you had a turbo you would want to boost too.

Countless members had a bad experience with something besides a Motorcraft thermostat. In other words why would you want to try something else and have a fail????? So just buy the Motorcraft and save the hassle.

Motorcraft thermostat for sure, used others without the results a motorcraft has. And, make sure the popit ball above the stat is freed up. You cant miss it. Clutch fan, works the best as well.