Wedge 80 TR7 PI where does this go

[Got_All_4]

Put 35 miles on the car today and noticed the temp gauge does not work. In fact at times the needle seems to start to climb and instantly drops below the "C". Did some snooping around the coolant sensor area and found that the coolant temperature probe is not in the block. You can see it sticking up in the pic. Could not find where there could have possibly been one. No plugs anywhere. Any ideas?

 

[JodyFKerr]

I'm not totally familiar with the TR7, but I have a very similar probe on my TR8, and it connects to the overflow cannister.

Jody

 

[George_H]

Looking at the shop manual, I believe its called the Thermotime switch. Its a time delay switch that feeds temp. info to the ecu. I would assume to aid in warmup?

 

[Got_All_4]

Today was much warmer day and the temp gauge did work. It would only get a tick past the 1/4 range then drop back slightly to just below 1/4 mark. All that needle fluctuation gives me a concern of a bad head gasket. But seems like all but one Tr7 I test drove had temp gauge problems or didn't even work.

George in the diagram it shows 3 probes in the block and that is my set up. My question is the 4th one. It's on the right side of the pic and has the conventional coiled type sending wire unit attached to the probe which the probe isn't attached to anything. Got to be for something.

 

[Deleted member 8987]

Temp sender, maybe, corroded connectors, maybe, t-stat bad, probably, low water level, likely.
That mechanical sender line you're talking about...where does it go? Other end, I mean. Under the dash? Bets are some PO had a mechanical gauge installed.

 

[Got_All_4]

You may be correct. There is an after market oil pressure gauge under the dash so possibly the PO had both mounted and removed one. I'll look tomorrow and see if there is any evidence of a former gauge.

 

[tr8todd]

The needles spin on the gauge shaft and uncalibrate themselves. You will find many wedges that have crazy temperature readings. They often need to be "recalibrated" by adjusting the needle to the proper readings. Same thing with fuel gauge readings. This comes about from people taking apart the gauge cluster to clean dust off the gauge faces. Unwittingly the wiping of the gauge faces will spin the needles on the shaft. Since they are spring loaded, they will return to the off position and you won't be able to tell by looking at them. I think JClay's site has a chart showing what the gauge should be reading based on actual coolant temps.

 

[Got_All_4]

Figured out what was causing the temp gauge to fluctuate so much. The spade terminal was very loose on the sending unit. The rivet was not fully crushed so I took a punch and taped it down. Now I have a steady working gauge and the car seems to run better. Not sure if the ECU gets it's info from that sensor but I'm sticking to my story.