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I am trying to rescue a 1982 Silver Spirit that was being sold for parts. I finally got the car running after new fuel pump, filter, fuel injectors, fuel distributor rebuild, warm up regulator fix, new belts, tranny contact clean, etc. But the temperature gauge does not read anything - never comes off bottom of gauge. I can not tell from the diagram in rrtechnical page M17-24, where the sender sensor is for the temperature gauge. I notice that on top of the thermostat housing there is a 2 pin plug with nothing plugged into it, but there is no loose connector nearby. Can anyone tell me where the sendor unit is located ? If on top of the thermostat, does anyone have a picture of this connection ? Thanks.
 

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I see from the diagram and posts that UE40361 is called the Coolant Temperature Sensor. Looks like it is on the lower part of the thermostat housing on the air cleaner side. Is that for the temperature gauge ?
28413
 

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Thanks for the confirmation. I pulled off the connector and the connector fell off the wire. I grounded the stub and the gauge read max. temp. Good news I suppose. But I replaced the connector and see that the gauge still reads totally cold (bottom of gauge not budging). So I suppose the sensor is bad. I'll get new sensor and try that.
 

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Does the temperature gauge display anything off dead zero when engine is cold ?
I just replaced the sensor, but checked resistance of the new unit and got, I think 700kOhms. When I checked the old unit it also had 700kOhms. So likely the real culprit is broken wiring ? The last 6" of wire is brittle so I it out soldered in new wire. When I turn on the key (not running yet), the gauge doesn't flicker and still shows below zero, but if I take a short wire and short the sensor to ground, the gauge moves up to max. So perhaps the gauge reads below 0 until engine warmed up. In the past, the gauge never moves up at all, hopefully when I test tomorrow will show something.
 

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In the SY2 cars, and yours is very similar in this specific regard, the temperature gauge does not move for quite a while. I'm too tired at the moment to think about exactly where the temperature sender is in the coolant flow, but remember that no coolant is allowed to go through the thermostat to the radiator until the coolant has had a chance to heat it enough to open it. Even though I believe the temperature sensor is below the thermostat, the coolant is so far below normal operating range (meaning, as far as the sender is concerned, dead cold) that it is not going to move up for a while.

What's really different about these cars is that the temperature gauge actually moves through a lot more of its range toward the upper end as the car heats up under stress (like driving up steep hills, running AC when crawling along in a traffic jam on a really hot day, etc.), and that's entirely normal. There are many newer cars (and I owned one in the form of a 1999 Jaguar XJ8L) where the temperature gauge really isn't. It will rise to about center, and never deviate from that position so long as the temperature of the car is "within normal limits." It's essentially an elaborate "idiot light" and actually has an LED in it that will illuminate if the temperature gets too hot. Lots of cars behave similarly, and people get used to temperature gauges "staying steady" when, in the past, they did anything but and responded to variations in normal operating temperature by reflecting same on the gauge.

I can't remember if the early SZ cars used "the white band" as the way of marking the normal range of temperature, but I think they did.
 

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Guyslp, thanks for the info. That is good to know, if I see the gauge varying, I won't panic. This care was dead and on way to scrap metal yard and I got it running, but now it is catch 22 time because I'm afraid to drive it more than 3 minutes, because I can't tell if the engine is headed to overheating and destroying the engine. The overtemp dummy light came on once, hence I wish I had a gauge that ever showed anything. I temporarily removed the return hose to the radiator and water gushed out, so I know the pump/thermostat are allowing water to flow.
Perhaps I can try removing the radiator cap and then just letting it idle - I should see the GAUGE budge off zero before coolant boils out of the radiator.
 

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One thing you can do to at least put your mind somewhat at ease is to obtain an infrared "gun style" thermometer and take readings at the top of the thermostat housing as you drive. Unless you have some really unusual situation, I would not expect that you will be overheating if the coolant is circulating. Now, if your thermostat is stuck open, which could definitely be the case (see: Thermostat Issues and Selection) you could have an engine running cold and staying that way because coolant is circulating through the radiator before the car warms up, which means it will never really have a chance to warm up.

These two threads on the Australian Forums (I don't know if I posted here, but I may have) are about the SY cars, but the SZ cars use the same engine and the same thermostat, so, by extension, one would expect the same (or really, really similar) specifications and readings:

SY Operating Temperature Data

Within Normal Limits: Operating Temperature Range
 

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Update and resolution: Thanks to all, especially GUYSLP, I bought the infrared sensor and let it run 15 minutes. the reading on the outside of the thermostat housing climbed to about 180. You are exactly correct, the gauge only moves off zero at around 150F. 180 barely got it into the white range. With this I can drive around with some level of ease !!!.

After several years sitting it is still burning off all kinds of residue so the engine bay is smoking like a Texas brisket smoker, but I carry 2 fire extinguishers and the smoking is getting less and less with each drive.

Thanks !
 

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If you have valve cover gasket leaks, and particularly on to the exhaust, you can still get puffs of smoke when the oil hits the pipe!

If your car has carbs (and I think at least a few early SZs for certain markets did) or has a flame trap be sure to make certain the flame trap has been cleaned out. You can stop or minimize a lot of valve cover oil leaking when the flame trap is clean since there's far less pressure in the crankcase when flow through that piping is going as it should.
 
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