Is my truck running too cool?

[Dante04SRT]

Now that summer is here, I'm surprised at how cool my ECT is, even on hot days. Using yesterday as an example:

86* outside
65mph on flat highway, no trailer
Truck has been on all day, driving, so yes, it's warmed up.

My ECT is 179-182*.
My EOT is 189*.

Both of these numbers seem low compared to the temps I've seen others post. Shouldn't my ECT be around 190-200?

I did change the thermostat when I did the coolant flush and switch to ELC, but it was this way before all that anyway. I'm not really worried, just kinda puzzled how my truck with 143,000 miles on it runs so "cool".

[HeavyAssault]

Maybe test the coolant, you may need to add some water.

[Dante04SRT]

Originally Posted by HeavyAssault

Maybe test the coolant, you may need to add some water.

Ya mean as far as the ratio of coolant goes? It should be 50/50 as per the instructions for the flush and fill.

[<Tug Daddy>]

I've been reading that the thermostat opens at ~192.5 degrees and I've also heard ~184 degrees. I have to really be cruising (65+) to get my ECTs above the 190 mark and stay there and I have about 118k on mine. When I'm grannying (cruising @ 55), It stays around 188 or so, with EOT around 194ish.

I am running full synth oil and the stock ford antifreeze, but nothing special that I know of...

[jetjock15]

too cool? I think you fine. When i was in Alaska i couldn't get the gauges to come off the cold stops, i had to seal off the entire front end to get 140 degree readings. In the dead of summer there is nowhere in the states that you need to worry about being to cold

[2003kingranch]

mine usually runs EOT 192 and ECT 188

[PGreenSVT]

The thermostat starts to open at 89*C and is fully open at 104*C. That has been stamped into the thermostats I have seen and used. If you do the math those temps equal 192*F and 219*F. I would expect theer could be a 2%-3% variation from those numbers either way. I just replaced my thermostat and it appears to open at 196* according to my Insight.

I don't think you will have any problems with your truck running those temps but they are on the low side. Diesel engines like heat. It will run more efficiently at 200*F than it will at 182*F. I have been told that 215*F is the optimum oil temp by a number of engine builders. I don't know how to verify that but it seems a reasonable oil temp for a diesel running near 200*F.

[HeavyAssault]

Originally Posted by PGreenSVT

I have been told that 215*F is the optimum oil temp by a number of engine builders. I don't know how to verify that but it seems a reasonable oil temp for a diesel running near 200*F.

How could this correlate to the ECT/EOT deltas as imposed by Ford? If this information was determined to be valid we got a whole different ball game when watching ECT/EOTs.

[PGreenSVT]

Originally Posted by HeavyAssault

How could this correlate to the ECT/EOT deltas as imposed by Ford? If this information was determined to be valid we got a whole different ball game when watching ECT/EOTs.

The key word there is DELTA. It doesn't talk about absolutes. Consider back in the day when it was common to run 160* thermostats in our hot rods. Now they run motors at 190*-200*. Ford's concern with the delta is that it is an indication of a problem with flow through the oil cooler, not the absolute temp of either.

By default my Mustang doesn't kick the hi fan on until 224* IIRC.

Consider DieselSite's 203* thermostat for the 7.3 to make it run more efficiently.

It's all the same ball game with the same rules. Nothing has changed.

[HeavyAssault]

So running engine oil at a steady 210*F with coolant at a steady (in relative terms) 190* is a problem? Even when using an EGR delete?