Sorry for my late expression of interest in this mod, too; count me in for BOTH oil & temp gauges. Awesome mod! Thank you WhiteXKR!

 

Great questions...did you ever get an answer???

 

RealGauge has been available for some time now, see: RealGauge - TheJagWrangler

 

I read most of the thread and have determined that the stock Temp gauge is basically useless. Here is my issue. Two months ago my "add coolant" message come on. I added a small amount of the orange Jag coolant as needed. I than begin to pay attention to the gauge. I noticed that it about 5 minutes of running the needle went to the 1/2 point point and stopped. I had noticed it before there, but never paid attention to how long it took to get there. I do live in Florida and it is over 90 degrees. I never had an issue with leaking fluid and it never appeared to be overheating, although it smelled a little like and engine that was hot when i parked in the garage. About 2 weeks ago, the "red light" came on and immediate parked it and had it towed to the mechanic. They tested and flushed and replaced the thermostat and filled with new orange coolant. (Damned expensive stuff). I picked up, drove it a few days and noticed the gauge was going to half way in about 5 minutes again. Than on Monday, the red light came on again.n I called the shop and they said they ran the car and the temperature was good, so may be a faulty sensor. It is at the shop and they are running it again, but said everything looked fine from a cooling perspective. They could not get the Red Light to come on. They are going to check sensors.
So, is this fairly common? Should I be concerned?

 

Have them also replace the cap on the coolant reservior. If it is leaking pressure or the pressure release valve is malfunctioning you can overheat sporatically and lose coolant. It is just a few bucks and 30 seconds of labor.

 

Thanks to all for a very interesting discussion. My question is about the gauge but also about the entire cooling system. I understand that with most OE cooling system alarms (lights or gauges) they can only read info from the sensor. In the situation where you have a slow leak (as you are driving along) it is possible for the car coolant level to fall below the sensor point without getting hot (yet). In this case the temp gauge will no longer read coolant temperature (its not very efficient at reading air temp) and when the coolant is finally gone to a level where the system can no longer cope the first info the driver has is when the car comes to a grinding halt with the temp gauge still reading "normal".
I understand the XK has a "low coolant" warning indicator - will this alleviate this problem?
I have actually destroyed the engine of a lesser car this way so I am a bit sensitised to this design "flaw"
thanks
jd

 

The low coolant sensor circuit is for that reason, to warn when coolant is needed. If it is functioning, there will be enough warning to avoid the scenario you describe. (Big If). Also helps to pay attention to the behavior of your temp gauge; if the coolant is real low, the gauge will be reading lower than normal until the engine really overheats. Sorry about your prior mishap. One more reason why we need actual functioning readouts in our cars. A sensor that reads the actual engine block temp and sounds an alarm in a overheat condition would be a great, minimal cost addition by the manufacturers. But we're not supposed to concern ourselves with such minor details; after all our cars will soon be driving themselves. (Rant)

 

Regardless of what your gauges and lack of warning lights tell you, make it a habit to remove your reservoir cap and eyeball your coolant level at least weekly. Takes less than 30 seconds and is the safest method for detecting problems before they turn catastrophic....

I check all three of our vehicles' fluids and tire pressures every weekend without fail. For both Jaguars, the first task on my checklist is always the coolant level check....

 

Not to sound too stupid but, I check every Saturday
Morning and it is at 1/2 way full. Is that where it should be? BTW, RealGuage is great. Helps you to learn your car's "normal". Normal cruise for me is 200-205. Stuck in hot traffic will go to 215-220 and drops as soon as traffic clears.

 

When boating, it's check everytime you leave the dock.........my rant was about things that develop while underway, either with boats or cars, in- between routine inspections. Nice to know if you're losing coolant, or oil pressure, or filling up with water before it's too late to save your engine.

 

I don't understand all the hoopla over the temperature gauge. My XKR's temperature gauge reads exactly the same as the OBD II readout from a OBD II scanner. When I start the car it accurately reads ambient temperature. As the engine warms, both the dash gauge and the scanner increase in value. Note that the dash gauge does not have numbers, only relative needle position. Of course the scanner is displaying numbers. When the engine is operating at normal temperature, the needle is mid way on scale and the scanner is reading 196°F fluctuating to 210°F or so under acceleration. Then cools down as I let off the gas. I suppose that the dash temperature gauge on a nav equipped is getting that temp from the ECU.

 

Yes, the gauge is accurate at the low range (actually it reads 125F to 185F) accurately. Then from 185F to approx. 235F it is dead center. Above 235 it jumps to the top of the scale within about 3 degrees or so. When it reaches the top of the scale the red iight goes on also.

Now, you stated your typical normal max. is 210F. What if one day, due to a sticky thermostat you started operating at 225F normally? Wouldn't you want to know that your cooling system is beginning to fail before it actually overheats into the danger range? Then you can repair it before you ever overheat. Same for wear on the water pump rotors. It is not guaranteed, but quite often the cooling system degrades before it actually gets bad enough to overheat.

BTW, non and non-nav. cars get their temperature information directly from the ECU. The ECU reads an electronic coolant temperature sensor. It is the instrument cluster that 'dumbs down' the data.

 

I picked up the Jag today from the mechanic. He said he went through it completely, ran it for over an hour, drove it for a while and tested the temperature and said it was fine. The gauge is dead middle, but the red light comes on. Any thoughts?

 

I installed the RealGauge set (highly recommended) and after a few days began to get the red light too. Temp stayed perfectly in the 198-200 F range.

Fix was replacing the oil pressure switch. It was cracked at the base and I guess I made it worse installing the upgrade. $20 on eBay and it has been fine ever since.

 

Normally the gauge will peg to the top when the coolant red light is on (they are affected by the same sensor data), so this is strange behavior. If you want more peace of mind get a cheap OBDII reader on ebay (search 'ELM327') and monitor the temperature yourself for while. Although it would be exceedingly rare, there could be a fault with the red lamp indicator.


Edit: Based on JAg #4's comment, I should ask: WHICH red light?

 

Some dumb questions/comments. My gauge goes up to operating temp in about 5 minutes (Daytona Beach), so that's probably normal. Which red light goes on? Steve knows more about how the instrument cluster works, so hopefully he'll be able to help. Are you driving the car under different conditions than the garage? Do you have an OBDII scanner you can plug in and try to read the true temp when the light goes on? Do you have a IR gun to shoot the real temp of the engine? I have to check, but alot of vehicles have a seperate sensor for the idiot light vs. the gauge. Some thoughts.

 

I am driving under the same hot Florida heat. The gauge goes to middle in about 5 minutes as well.
I am going today to buy the scanner . Will check the temp myself. Light is annoying and concerned to drive long distance until I am convinced it is good.