Hey everyone. I recently did a rad flush and fill in my '94. I put in a new thermostat (I bought a high quality Stant from Advance Auto) while I was at it and now my truck is running hotter than it used to. Before, the temp gauge would read between N and O, occasionally ventruing up to R. Now, It goes as high as L and the temp fluctuates frequently while driving. I've got no leaks, no milky oil and I can't smell antifreeze when the truck is hot. My question is, is it possible the old t-stat was stuck open and my truck ran too cold, or I still have some air in the system (I purged it as best I could). I'm just curious to know what everyone else's truck runs at and if it now runs where its supposed to and I'm freaking out over nothing. If I do have issues, I would love to hear some suggestions for a solution. Thanks in advance for any help.

 

possibly air... what temp T stat did u take out and what did u put back in. air may be causing the fluctuations *hotter when air pocket is under the sending unit and cooler when is got coolant flowing over it* as for the readings on the gauge.... ford is off no 2 are the same a 195* Tstat in mine might read on the n and o part and one in urs might read further over like on the o or r. as long as it isnt on the red mark or as long as u dont hear it boiling in the resivour ur ok. try to get the air out and see if that helps

 

I have a mecanical guage in mine along with the stock, at 195* mine is between the "n" and "o". Could be air or a faulty stat, I had to put two in mine to get a steady reading, the first I left in for a month hoping it was trapped air, and the new one only took and drive to get steady readings. But I drilled a 1/8th inch hole in the new one, just in the edge to help ppass trapped air. I installed the hole to the top of course.

 

Well, I guess I dodn't do as good of a job purging the system as I thought. After a round trip to school today, I now have a steady reading between O and R, once I get up to operating temp. There might still be a few tiny pockets of air in it, cause it will occasionally and intermittenly go up to between A and L. I've got great heat, and no boiling in the rad or bottle. Before I did this I also had some pretty loud gurgling from the heater core, and this should have been the tip-off. Thanks alot for the help. This forum is great for do-it-your-selfers like me.


BTW, I took out what im assuming is the original t-stat since it was Motorcraft and replaced it with a 195° Stant unit. I've always had good luck with Stant t-stats, and didn't have 3 days to wait for one from the local Ford dealer.

 

I've used Stant products for many years with great results.

 

I like to use the "spill-free funnel" that I purchased from the tool man. The one that attaches like a cap to the radiator. It works great, and gets all the air out the first time.

It's great for purging, especially on this f150 I have now, since it has this constant flow by-pass hose running right in the top near the rad cap. It shoots coolant out if cap is off while you're trying to purge it otherwise.

As for the temp gauge mine runs between N- R

 

well this makes me feel better; I've always thought something was wrong with my truck since it sits right on the N, barely reaching the O when I really get on it. I guess the gauges are just that far off.