Howdy folks,
quick question for you as I've noticed a slightly odd behavior from the coolant temp gauge. Firstly, I know the gauge is heavily damped in the normal setting and essentially nothing more than a dummy gauge. That said, you would think that the gauge needle would rest at the same place every time. Generally, my gauge needle sits just under the middle line, like this:



But occasionally and for no apparent reason, it sometimes sits bang on the line. Such as:





It doesn't move from this point and there is never a sign of overheating, so I can't figure out why this might happen.

Does yours do this or is mine "special"?

 

One question....Does the ambient temperature (what the thermometer says) seem to have any impact?
In other words...on a cold day is the needle lower than on a hot day?

 

Maybe your thermostat is sticking partly open and preventing the engine from fully getting up to temp?

 

No, i figured this might have been it, or maybe the cooling fans being on from startup with the a/c or whatever. Took the same drive at the same time this past saturday and sunday. First trip temp was about 50 degrees and the gauge stayed below the line. Second trip was 35 degrees and needle was on the line. Return trip same day...just below the line.

I've checked the temp with a elm obd tool and there is no apparent difference in the coolant temp (which is like 190ish with some fluctuation) when this happens. Thermostat is new and the temps seem to act normally.

This is not really in issue although it does momentarily cause some concern as i'm not certain if the gauge is rising or just chilling at the higher level.

Just wondering where the needle in your cars sit.

 

On modern Jaguars these gauges register always just a hair under the mid point. This is intentional and it is the same no matter which model you are driving; once the engine reaches normal operating temperature the needle stays glued to that position. As long as the computer registers a normal temperature given changing conditions - which can and do vary - up hill under load, down hill, extreme ambient temps, no matter…it always reads just slightly under the mid point. This prevents nervous drivers from becoming agitated. The drawback is that if the car truly overheats the needle will alarmingly rise to the danger zone very quickly!
But your concern is that the needle sometimes registers just above mid point.I doubt that this matters at all. If there were a concern that needle would be at the top end.

 

right yes, the buffering I'm aware of. I'm guessing the temp sensor may just have teensy but of build up, scale, or wear that causes just the slightest of differences in resistance. Or the gauge is a bit sloppy. In my research I've seen it both ways on the internet, so i'm not gonna sweat it.

 

middle starts at like 70c ect

it’s just the gauge don’t worry about it

 

I don’t have this on any of our X308’s but, I will soon. I’d recommend this if you want to get away from the factory broadband switch gauge. The only caveat is that the gauge will move around more and you’ll need to get readjusted to it.

https://www.thejagwrangler.com/xk8--...realgauge.html

 

You could compare the OBD2 temperature reading with your gauge and compare
the two in both high and low gauge readings. That could console you a bit.

 

The cheapest way to stay on top of the engine temperature is to use Torque Pro. Any old phone and a $5 app and then you can watch it in real time.
.
.
.

 

I've had the Real Gauge (A2B's post above) on my car for a few years and love it. I'm convinced that it has saved me from blowing a head gasket as it starts squealing when you hit 236F; 244F is the magic number that you don't want to cross. I live in a high altitude area and the Heaton goes crazy when I'm going up a steep grade, so it tells me when to shut it down and take a break.

 

Hispeed, can’t you just turn the heater on full blast (A/C button off) to help keep the temps under control?

 

I’ve been running into something similar where the needle sometimes rests in the middle or all the way up on high even with the car off all night. I’ll start it 1st thing in the morning and sometimes the needle goes all the way past towards the gas gauge and it gets quite chilly in the mornings so I’m stumped to why it would do that. I had a tech check it out and he said there was like nothing wrong with coolant like it wasn’t low or anything. I’m not a big car guy idk what I’m doing here…anybody got any ideas?

 

One word, "RealGauge" this little bit of hardware turns that into a proper temp gauge with audible warning in case of an overheat event. An engine saver designed by a forum member, whiteXK

https://www.jaguarforums.com/forum/x...unction-74704/

https://www.thejagwrangler.com/xk8--...realgauge.html

 

The gauge needle is electronically held around the middle point for the sensor signal from around 70C and up to some 100+C and then it quickly goes to "hot". So, where exactly around the mid-point the needle sits is not influenced by the variations in the sensor signal (over the mentioned temp range) but is determined by the special electronic circuitry inside the gauge that keeps the needle in the middle. The electronics might be in one mood on one day and in a slightly different mood on another. Or the electronics may act on the needle a bit differently at different in-car ambient temperatures.

In any case, a totally useless gauge except for the purpose of stopping certain owners complaining to Jaguar about the temperature sometimes going "high". Long time ago I had a Daimler Double Six (5.3 Lit) which had its oil pressure gauge pegged electronically at a very "healthy" level. No more complaints under warranty that the oil pressure is "very low" at idle.

 

Yes, it is true...the Temperature gage in the stock X-308 is basically no better than a warning light.
While said gage may be adequate for some users, others will find it less informative than what they
require and in such cases, we have the Real Gage alternative. Another alternative would be to use
the temperatures reported to your OBD2 when you want to monitor your exact temperature. It is
somewhat appalling that the Jaguar engineers did not insist that a true reading gage be installed
on such a sophisticated car, but perhaps they were overruled by the bean counters.