I have a Jaguar X Type 2 ltr diesel which I bought second hand a few months ago. The engine temperature gauge always reads low (the needle rarely moves past the one third mark on the dial) and takes a very long time to indicate that the engine has warmed up at all. When cruising/descending a fairly long hill the needle falls right back into the blue (cold) area of the gauge. I have talked to the local Jaguar service agent about it but he assures me everything is alright. I am not so sure and wonder if the thermostat needs replacing. Having never owned a diesel before I do not know how the temperature gauge should behave. Can anyone advise?

Richard.

 

Richard, first off, welcome to the forums. I think you will find lots of straight forward answers here and lots of friendly conversations too. But, we do ask a simple thing from you though too. We pride ourselves in being a slightly different car club in the fact that we treat it more on a friendship basis than most. As a result, we like to get to know one another. So, please stop by the New Member Section and introduce yourself. Tell us a little bit about yourself. This will help you get to learn who the key players are around here. You may even get a nice surprise in the end too.

As for your problem, the X-Type temp gauge should come up to the mid point for normal operation for all motor types. Based on the fact that yours is not, tells me that there is something wrong. I would first start with getting your hands on an infrared thermometer and taking a temperature of the upper radiator hose or of the radiator itself. Both of these should be reading in the neighborhood of 180-190F (85ish C). If you are down around say 60C, this confirms an issue.

Based on the temp that you get, if you are up around 85C, then this confirms that your issue lies more with the electronics of the car vice the mechanical aspect of the car. Odds are, this would be due to a bad temperature sensor. A new sensor can be installed for fairly cheap and in this case should correct your problem. If you are suspecting that it is a temp sensor, you can also put the instrument cluster into a diagnostic mode and it will tell you the temperature that the computer is seeing (if you want info on this, let me know and I will explain to you how to do this). It could be something as silly as the needle for your temp has some how gotten moved and it is simply reading wrong. But, based on the fact that you mention that the needle moves when you drive down the highway tells me that this probably not the case as the computer is set up to allow for a slight variance in the actual temp while leaving the needle on the instrument cluster in the same position.

If you are getting a low temp on the radiator hose, then odds are, the internals of your thermostat have come apart and it is allow too much water to flow through your radiator, resulting in the motor running too cold. A new thermostat would fix this problem. Just make sure that you can account for all the parts before putting it back together. Hate to see you leave a small piece of metal in the system and it end up causing a bigger issue.

 

Richard,

How far are you driving? My diesel takes about 15 miles to get up to temperature.

 

Hi Jonesy. It usually takes about 10 miles or so, but then never climbs very far off the bottom mark. Thanks for your interest.

Richard

 

Thanks Thermo. That was a very comprehensive response and has confirmed my suspicion that there is some sort of fault. I'm not much of a mechanic myself and don't have the facilities to be one where I live, but I shall print your diagnosis and take it with me to my local mechanic and ask him to investigate.

Thanks again

Richard