Originally Posted by JackandJanet
It's funny, this was a question I asked on f150online and I almost got beaten to death in "flame" posts - "Use the search button", "Who cares, the computer takes care of it", and so on.
Here's what I found out, pretty much on my own:
First, there's no actual sensor for the coolant, it's temperature is "inferred" from the Cylinder Head Temperature (CHT) sensor, so, I see no real reason to monitor it at all. I monitor the CHT, and, on hot days under normal driving it tends to stay in the 206-208 degree range. If I put the truck under heavy load, climbing a long hill pulling the trailer at higher RPM, I've seen it get to 216. Never higher. The coolant temperature gauge on my dash doesn't change at all, and, it really should be in the 195 degree range. That's what your thermostat is rated at.
A CHT of 258 puts the engine into failsafe mode and 310 causes the engine to shut down.
Oil temperature can really bounce around. I've seen it jump to 245 or so under heavy load conditions. Usually, though, it's close to the CHT. The only thing I can find on Ford's recommended oil is that its flash point is 365 degrees. The owner's manual says to change it every 3000 miles or 3 months if used in severe service.
According to the New Jersey Forest Fire Service, using f350 and f450 trucks, if transmission fluid is operated at no higher than 175 degrees, it should last about 100,000 miles. Prolonged operation at 195 degrees, it's good for only 50,000 miles. At 240 degrees, it breaks down rapidly, ruining it for further use. Now, our f150's don't use the same transmission, but I'd bet the fluid has similar properties. I've seen the TFT climb to the 210 degree range too, while pulling a trailer up a long hill (torque converter unlocked, in a lower gear and at 3000-4000 RPM).
Oh, I was worried about max RPM too, since there's no "redline" and we can adjust it with the Gryphon. The only thing I found was that the Torque Converter starts to "balloon" at 5400, so that seems a good limit to me.
I've never even thought of looking at intake temps, and have no idea what they should be.
There, no flames, no snide remarks, just the answers as I know them. And, I'm not an authority! If anyone thinks these numbers are wrong - PLEASE, chime in!
- Jack
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