Muzz 66 wrote:
TKOPerformance wrote:
The first thing to do IMO is verify that its actually getting hot. That's why I like knowing where the gauge sender is located. The temperature in the cooling system is not homogeneous. Ford likes to read the coolant temp in the intake manifold. If you read the temperature in the cylinder head or various places on the block, etc. you will get different temperatures.
Assuming its really getting to 230 a flush is indeed a good first step. If the bottom 1/4 or 1/3 of the radiator is packed full of junk your cooling capacity will be significantly reduced.
My ‘92 LX 5.0 has a dash gauge that reads high all the time these days. It also reacts to voltage. Lights on, goes up, fan goes on, goes up, A/C or heater goes up. Even the turn signals will slightly move the needle sometimes. So I installed an Autometer temp gauge. It reads more correctly. The sender for the stock dash gauge is in the intake manifold and the sender for the Autometer is at the top of the thermostat housing. Just today I used some test leads to “switch” sending units to the gauges to see what would happen. The dash gauge needle went dead to the bottom and the Autometer needle maxxed out to the top. WTHeck? Auto electronics are a big mystery to me. Anyone help me out here? I’ll start another thread if need be. Thanks.
Probably better to start a dedicated thread, but I don't know that you can do what you did. In other words, the Autometer gauge is designed to read off the Autometer sender. The sender for the stock gauge may simply not be compatible with the Autometer gauge. Temperature senders work by varying resistance based on temperature. The scale of the resistance values the sender creates must be matched to the way the gauge is calibrated.
You can test the stock gauge and sender. First test the gauge, because I think that's where your problem is, based on your description of the gauge reading. Turn the key on, but do not start the engine, disconnect the wire from the gauge sender and ground the wire to the negative battery terminal. If the gauge reads hot the gauge is probably fine, and the sender is probably bad. If the gauge reads cold or doesn't move, there's something wrong with the gauge.
You should be able to test the sender with a multimeter by reading resistance (Ohms) through the sender (terminal post to the sender body. Put the sender in freezing cold water and read the resistance. Then put the sender in hot water and read it again. The resistance values should be different (higher cold than hot). The sender is just a path to ground. The gauge functions off the ease of that path. The easier the path (lower resistance) the higher the gauge reads and vice versa. If the sender reads infinite resistance its broken internally.
Anyway, start there, but my bet is there's something wonky with the gauge.
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