Recently put new rad on , cant find where this goes (see pic) ,guessing this is reason my fan keeps coming on ,and staying on after I turn engine off. Is it a sensor ? Just can’t see where it goes.
TIA

 

I'm not sure where that connector goes. I compared with my '02 V6. It has the larger plug set at an angle on the back of the radiator shroud, just like yours. But it does not even have the branch in the harness leading to your mystery plug. Maybe it was only found on RHD models?

Not sure about that gray piece inserted in the plug. That kinda looks like something broken off another piece. Anybody got any ideas?

Re: The fan running after shutdown - That is a normal response to an abnormal condition. The computer is seeing high temperature and running the fan for a few minutes to cool things down. My car does that occasionally on very hot days, maybe 95F and higher ambient. But you're not going to see that weather this time of year in London. Something ain't right...

Why was the radiator replaced? Was it leaking? Was the engine previously running hot and this was a repair attempt? Or is this a new symptom?

What about bleeding the coolant system? After having the cooling system apart, Jaguar has a special bleeding procedure to get the air out of the lines. Myself, I'm lazy and have never done it. However, the cooling system will gurgle and belch and act erratically for the first few heat/cooldown cycles. The dealership couldn't return a car behaving like that to the customer, so they developed the bleeding procedure to speed up the process. Keep the system topped off as the air works itself out over the next few days and you'll generally be fine. I mention all this in case you've only driven one or two cycles after replacing the radiator.

 

Typically when the radiator fan runs on after the ignition it turned off, it indicates a sticking thermostat.

What engine is the vehicle fitted with?

 

Thanks for reply, replaced radiator because it had major leak ,looked like bottom had exploded! See pic. Got new thermostat as well so that’s ok. Engine doesn’t overheat, according to temp gauge and not losing any water. Thought it was an airlock and bled system. Would make sense if this connection is a sensor and it’s picking up the heat when engine is getting hot and turning the fan on , just can’t see where it should go

 

Replaced thermostat when I replaced radiator. Engine is 3 litre petrol

 

A guy walks into a bar and sees a man about 1 foot tall, dressed in a little tuxedo and expertly playing a miniature piano. He asks the bartender what's going on...

If you're going to tell jokes, so am I. I do not care to discuss how I've learned this, but there is never any guarantee of new parts being good. It can be a troubleshooting nightmare. I have found thermostats to be one of the most likely parts to be bad out of the box. It's got so bad, I won't install a new one without testing it first with a thermometer in a pot of water on the stove. The rated temperature is when the thermostat should first start to open, and it should be fully open 20F higher than that.

I'm not saying to rush out and replace your new thermostat. But I would strongly suggest you beg, borrow, or steal an infrared thermometer and measure the temperature at the thermostat housing to be sure.


Ah, welcome to the world of Jaguar. The gauge is deliberately misleading, with the needle parked in the center from approx 180-230F. More details here:

https://www.jaguarforums.com/forum/x...e-gauge-62813/

That's a different model, but the behavior is the on the S-Type. When my scanner shows "coolant temperature" above 230F, the needle starts to climb from the center position. If you have a scanner, you can see the actual data. If not, all you get is a vague hope the temp is somewhere between 180 and 230F. If the temperature is climbing towards the top of this "normal" range, you won't know until it goes beyond that. You'll have no early warning.

Also, please be aware the early V6 models do not have a sensor for coolant temperature. There's a single sensor that reads the metal temperature of the LH cylinder head, but nothing for the coolant itself as on most vehicles. More details here, including my travails with bad thermostats:

https://www.jaguarforums.com/forum/s...rature-186873/





Still hoping somebody else can chime in. I can't imagine that grey piece as some sort of sensor. Does it have any sharp edges on it, as if broken off from something else? It almost looks like a dummy plug, designed to seal off the opening of an unused connector, and maybe clip to nearby structure so it's not flopping around. Manufacturers often make a harness somewhat universal, with provisions for optional equipment. If not used, the extra connector just sits there.

 

DO NOT rely on the instrument cluster gauge to determine coolant/cylinder head temperature. Use a smart phone with the Torque app to connect to the vehicle's PCM via the OBD port with a Bluetooth interface to read various engine functions in real-time.

As Karl says, the gauge only indicates an overheating event when the engine is extremely hot at 128+ degrees C.

Since the vehicle has the 3.0 litre unit, the plug appears to be for the auxiliary coolant pump fitted to vehicles with the 4.0 litre petrol engine, which is not used thus the plastic insert in the plug.

 

Is the replacement radiator used? Appears to be, judging by the pictures. If so, it's quite possible it has scale built up inside, limiting normal heat transfer. Once again, beg, borrow, or steal an infrared thermometer. Compare the temperature at the radiator inlet and outlet. With normal airflow through the fins, you should see at least a 30F temperature drop across the radiator or it isn't doing its job.

 

Thanks for replies, gonna put back original thermostat just to rule out , makes sense that connection is a dummy plug, its not broken off from somewhere. Yes rad was used so obviously could be that. If still getting fan coming on after swapping thermostat, will get digital thermometer and try to suss it .👍

 

Call me lazy (I take is as a compliment) but I’d be more inclined to spring for an infrared thermometer first, before doing any actual work.

I still remember the first time I saw one, maybe 30 years ago at a radiator shop. The mechanic quickly diagnosed the fault and was 100% correct. Saved his time and my money. I was in awe, as if I’d seen the future.

An infrared thermometer probably cost several hundred dollars then. Now you can get a decent one for maybe $30. Money well spent in my over-inflated opinion. You can use one for so many things, not just chasing a cooling problem. I think every mechanic should have one. (I’ve got two, plus a thermal imager…)

 

Put original thermostat back on and took a drive and left it running when I got back. Fan didn’t come on so hopefully that’s it sorted. Although fan didn’t always come on any way but fingers crossed. Thanks for all replies.