Hey there! my temperature gauge stopped working today. it always worked fine. I checked the wires behind the gauge and everything was connected. any tips on where to look?
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Stock location of the sensor is the swirl tank. The preferred and more desirable location is in the block near the outlet of the water pump.
Disconnect one of the wires on the gauge. With the ignition off see if you have a resistance across the 2 wires.
The water temp reading is one of the main reasons the erroneous perception of 'overheating" was applied to Panteras. Grounding of things on the dashboard or the aux gauge panel is problematic. Both panels are fiberglas so each device has to have its own ground (some are daisy-chained) and things loosen up over time. Before spending money, try tightening up the gauge connections, then remove the engine access panel behind the seats & under the upholstered back panel, to reveal the front engine area. The sender connection on some cars is a spring loaded push-on type that sometimes just pops off- or fractures. Remember, this is a 50-yr-old sports car, often driven hard with people of unknown skill levels working on it! That includes shop personnel as well.
As mentioned, the preferred mounting place for the water temp sending unit (on millions of front-engined Ford products) is under the block's thermostat mount and has a square head pipe plug on Panteras. Removing the plug and the sender from the swirl tank, the parts interchange: the block plug fits the hole in the swirl tank. On the sender, one (1.0) layer of teflon pipe tape is all thats necessary; too many turns of pipe tape will partially insulate the sender from grounding so no or an incorrect reading will occur. A good VOM meter will tell you if this is what happened.
The normal engine water temp on the road may be 215F and the early gauge had a 0-220F range. Some owners were freaked out by the "pegged" water temp- which was perfectly normal. Do not be surprised if the water temp reading is well off reality. Ford attempted to "adjust" the readings lower to make the gauge readings less scary without actually spending much development money. We think that's why the sender was put remotely in the swirl tank- to lower the gauge reading a bit. Problem with that location is, if the water temp drops below the sender level in the tank, you begin reading the air temp above the water level, causing a false sense of security. Best to simply move the sender. If you're going for the 'totally stock' look, buy a second cheap sender and use a dummy wire on it- the engine mounted sender cannot be seen without disassembly.
Further, the Italian gauge and the U.S. sender have been found to be incompatible for true temp readings, so the Ford TSBs mention two different resistor values (5 watt & 10 watt) spliced into early gauge wires back in the engine compartment's taped loom. Some were simply twisted together, not soldered- check this; a loose connection may be the problem you're having. If you're comfortable working on the mostly-Lucas based wiring, a temporary adjustable resistor could be used to determine exactly what value gives true readings on your particular car. Then a resistor of that value could be soldered in the gauge wire.
A final factory fix for a previously inaccurate gauge was a 0-260F gauge that was stock for 1973-up. Many owners simply install the late gauge which tends to read closer to the correct water temp and is a drop-in modification (one of a very few!) once all the resistors (if any) are deleted.
Next- the inaccurate stock oil pressure gauge....