Guys,
My '99 with 194k on odometer is acting strangely with the water temperature gage, yes the original broadband switch model. When driving on the highway the gage drops to half way warm but around town shows the dead center. Never seen this before. Any ideas?
Thanks!

 

Best is probably to get an actual read off the sensor over OBDII. A cheap eBay/Amazon ELM327 would do fine. Sounds like a thermostat stuck open, but with the data you would get a better diagnostic.

 

+1 on getting the actual temperature with an OBD scanner. You should check the connector to the Engine Coolant Temperature sensor and possibly may need to replace the sensor.

 

This is very alarming behaviour.

I can't recall another report of a Jaguar gauge actually responding to changes in coolant temperature. It's almost as if it was WORKING!

Good advice from fmertz and avern1. Don't take risks with even a hint of possible overheating.

Graham

 

While we are on this subject, what is the proper operating temperature as read on an ELM 327 dashboard?

 

Depending on your thermostat you should expect to see 195 degrees F. The ECM will let the temp get to 212 and then will kick on both fans on HIGH to bring the temp back down. On the highway you should see about what your thermostat temp rating is.

 

just putting this out there as I am leaving on a long trip (800ml) in a couple of days, I consistently run between 198F and 208F on the hwy a little hotter in heavy traffic does this seem ok. I keep an OB2 monitor on at all times when on long journeys to keep my self sane as the original equipment gauge is not very helpful. Just installed a new temp sensor and pipe assembly after last trip will see if it makes a difference.....Heading for the Sunshine, had enough snow :-)
Jeremy

 

That's not too bad, but it depends on the thermostat. Some open more quickly than others. I have a new OEM one that runs around 181F, so I replaced it with my old one that is 197- 201F.

 

My 99 runs the same temp range yours does Jeremy. I use a OBD scan gauge which keeps a close eye. I've moved my front plate lower on the bumper over rides which lets more air in. Seems the system is set up for speed. Faster you go the cooler. Let us know how your trip goes. Rich

 

Using my OBII scanner and DashCommand app , mine is pretty steady at 186

 

Ran a little over 300mls yesterday before stopping, car ran at 205hwy pretty consistently.
In heavy traffic went up to 212-214f
I did move the front plate down lower some time ago and that definitely helps air flow.
I did notice that when I restarted after a lunch stop approx 40min that engine ran ruff for first minute then went to a mormal idel. While ruff STFT1 went to +24 then backed down to zero. I'm thinking that as she was very hot when I parked it may have been a vapor lock in the fuel line. Anyway fuel economy is great getting just under 25mpg and experienced no other symptoms, will keep monitoring the temps today expect to go about 250mls
Anyone any thoughts on that ruff start?
Cheers
Jeremy

 

I am told OBD which my Scan Gauge 2 uses, takes reading off the top of the cylinder head. I believe the dash temp gauge reads off the block. I assumed reading off the head is why my scan gauge temp readings varies so rapidly. As we know, temperatures do rise before it cools. On occasion during summer months if I park for 30 minutes or so after a 30 plus minute run, on re start, engine does get a bit rough for a moment. Never worried me. Rich.

 

Not true. They both use data from the same sensor in the pipe connected to the upper radiator hose.

The ScanGauge is presenting the actual readings. The dash temperature gauge is computer filtered by the instrument cluster to stop at 185F and remain there until the temperature reaches about 235F. It then rapidly rises into the red region in the space of 3-4 degrees.

 

Ok finished a second run of just over 250mls. Ran great all fuel trims running below +5, after lunch break restart a little ruff but ok after 30sec, stft1 still went high, think I'm going to change my coolant when I make my final destination. Give me something to do during next 2 weeks,brought all my tools��

 

I noticed a leak and had my water pump replaced and now all seems good. I will take it for a long drive and see if the gage/thermostat problem is fixed. Strange to me that a water pump would cause the symptoms.
Thanks to all who helped!
LaRue