Engine temps.

[Jackpine]

Originally Posted by BlackSTX

I'd hate to imagine what the oil temps looks like, I never looked, but will have to when I get mine back.
Also, I didn't realize the ECT was actually inferred.... interesting.

Yes, the whole ECT thing IS interesting, since we used to have coolant temperature probes into the coolant system (I remember having to replace one once when my engine overheated, ruining it).

But, they had a kind of "fatal" flaw. If the coolant went too low or boiled to the extent they were no longer immersed in liquid, they'd transmit nonsense values. The CHT temperature probe doesn't have these problems, since it simply warms up with the metal in the heads and sends (or passes) a voltage that can be interpreted as temperature. Since the coolant temperature has a clear relationship to the CHT, one can be inferred from the other.

I honestly don't know why we don't just see CHT on the dash gauge and be happy, except that years of the other reading are too hard to let go of.

The ECT dash gauge is really pretty poor in my opinion. About all it's good for is the "warning" that makes it swing to full hot when your engine is going into "limp home mode". It sure does not give you much "incremental" information on temperature changes.

The oil temperature is volatile as hell. I've seen it in the 245 degree range at high RPMs. And, I know from previous experience in an old Mercury, that it has a cooling effect on the engine too. If you let the oil get low, the engine will run hot. In that vehicle, the first symptom of low oil (it was on a long trip from Florida to Arizona when I was reassigned) was a gradually increasing coolant temperature. (I should have been more careful about checking the oil at each fillup).

- Jack