Cooling System Temp Sensor Position

[RRoller123]

Does it matter whether the Temp Sensor is at the front or rear head position? I have read here that the factory may have installed it and the Overtemp Switch Sensor in either location, but which position is the intended one? I am swapping mine out today, and I would like to just do it once if the position is of importance. Thanks in advance for any info you may provide! Pete.

[124JOE]

it can go ft or back it dont matter
the factory did switch them around from time to time
i have no idea witch one is witch on mine
just put it bsck in were the old one was

[courtenay]

My '80, all original has the 'spike' sensor closest to the rad.

[spider2081]

The wires for the sensors usually are not long enough to be swapped. The over heat switch wire is gray/black and the temperature sensor that drives the gauge for actual heat is green/white. If you reverse the sensor wire connections the gauge will not work correctly.

[4uall]

IMG_0491 by itzebtze, on Flickr



Sensor closest to firewall by itzebtze, on Flickr

[RRoller123]

Thanks all for the info, that sorts it out! These 2 sensors are not the same part, conflicting what I have read elsewhere. According to the schematic, one (Temp Gauge Sensor) is a thermally variable resistor, while the other (Over Temp Sensor) is a thermal switch.

In the driveway now tackling this problem. My gauge is not functioning, nor is the fan ever coming on, although it works with the overide wired in. It may be just trapped air, but I am flushing the system and changing out all 3 of the sensors anyway, and cleaning up the overflow bottle as well. Hope it all sorts out properly!

[RRoller123]

Well I tackled refurbishing the cooling system today because my truck was in the shop, so I had a free day to spend on the Spider. And it ended up taking most of the day. LOL. After draining the radiator, I pulled the Fan sensor and tested it in hot water; it closed properly at just about 190F. Hard to be more exact with only 2 hands when 3 are needed. Also pulled and tested the thermostat. It started opening at exactly 170F and looked to be fully open at about 180F. Both were OK, but I put in a new fan sensor because I had it, and the connector was fresher. I left the existing fan override wiring in place in case it is ever needed, but I sure won't miss searching around under the dash for that thing.



A plumber's thermometer works like a charm and is easy to use. I had bought one years ago at HD I think it was, when renovating the house.

Replaced both head sensors, the Gauge Sensor ( I never had any temp gauge indication) and the overtemp sensor as well.

Refilled the radiator, pulled the top hose and filled there, filled the throttle plate heater hose, jacked it up, pulled the plug at front and filled there too. No problem. Then lowered the car and noticed coolant pouring out all over the ground. The small hose from the T-Stat to Water Pump had 2 little breaks in it. Now I have no car, so I bicycled 3 miles to NAPA and got a long hose and cut out a piece (FYI: 1-3/8" ID fits quite well) and fixed that and filled and burped the system again and then started it up and just as it got to 190F (The gauge now works, YEAH!) the bottom Tstat hose blew up. Back to NAPA, replaced it and the clamps. (Top hoses are new). SO........... Refilled and reburped AGAIN and started it up and I'll be damned! It went up to 190 on the gauge, the TStat opened, the fan came on a little later and cycled very well. I was so amazed I watched it cycle 3 times.

And that's how to spend a great Spider day in the driveway!

Oh, but I forgot to mention that I will have to pull the radiator again, as the overflow tube fitting that is soldered to the radiator neck where the cap is, came off with the overflow tube, while I was checking the tube to make sure it was clear. I wonder if JB WELD will work to fix that? <{:^)

[4uall]

glad to hear it all worked out for you. When I was going through my overheating issues after recently purchasing Fiona I became so frustrated. After a friend came by to help I have never looked back and she never goes above 190F I also recommend all new hoses.

[RRoller123]

The hoses are all new now! LOL. I neglected to mention that the T-Stat already had the 1/8" hole, and that I fully flushed the radiator and block too. A productive if long and frustrating (at times) day.

[124JOE]

[4uall]

The hoses are all new now! LOL. I neglected to mention that the T-Stat already had the 1/8" hole, and that I fully flushed the radiator and block too. A productive if long and frustrating (at times) day.

hoses are on order currently one of them looks like a bloated snake on the higway

[124JOE]

dont poke the snake!!

[4uall]

I'll just call this guy


Billy by itzebtze, on Flickr

[polak]

Hi! Here is my problem, I am wonder if anybody could help me From few days the fan goes on later - I mean normaly it was about 200-210 F on the gauge. Now the fan goes on about 230-240 F on the gauge. So I have changed Fan sensor and the thermostat - nothing has changed Is it possible that there is something wrong with the WT gauge or the gauge sensor ???
Theoretically it works and shows the temperature.