Took the XJ-S out today for a good, 30 mile run and the coolant gauge read atypically cool with the needle hovering over C and never getting above the halfway point between C and N. Typically, it floats just at the bottom of the N.

When I got home, I got out the infrared thermometer and measured the right cam cover (between 87-88 degrees c), the left cam cover (90-91 degrees c). The coolant sensor (88-89) and the electric fan switch (which switches on 10 degrees cooler than OEM - reading 88-89 degrees c) .

To me, this all looks normal, if a hair cool, but the gauge read just above the C all the while, so I'm guessing my coolant gauge is either failing or the contacts have corroded over night or the sensor is failing. How would I know?

Now, it's the XJ-S, so it could all be normal again tomorrow but this has me thinking that, in addition to fixing this, it's also time for the addition of a more reliable and specific gauge.

For those of you who have fitted one (or two), where did you put the sensor(s), where did you put the gauges and what did you buy?

Thanks in advance,
Rhett

 

Rhett,I drilled the left rear cylinder head(considered the the hottest part of the Jag V12) near the AAV valve, and installed a small temp sensor for a DIGITAL read out gage ,reads in 2 degree measurements, much better resolution than OEM.
gage is on my ECU hand control, pix in my garage.
also have under hood air temp read out, drilled into left inlet manifold.


I like to know whats going on BEFORE a surprise happens!

 

I'm pretty sure that's where Shawn/smgdata put his. Its definitely on the opposite side from the original sensor.

I have an oil temperature gauge (with the sender braised into the sump) and 2 other temperature gauges..... one is monitoring inside the engine bay temps. The other monitors the outside air temp. Between all of this I can kind of work out whether I'm about to blow up or not. What is interesting from these gauges is how fast the temps change when you go from driving at a reasonable speed to stopping at a traffic signal. The engine bay temp can increase by 40degrees F in 2 minutes. Kind of scary.