This is the only criteria, not brand name, price, colour etc. Do not assume that all years are the same.

 

Saving to re-read later. Having same issue with 2002 S-Type.

 

I'm having the same problem. Here are some things I found from around the net from other people who had the same problem.

"Hi. I have a 2002 x type 2.5 which had the same problem of the temp guage reading normal one minute and in the red the next, turn the engine off and re-start and it was back to normal again for a few miles then shoot up to the red again. I knew the engine wasn't overheating, my first thought was temp sensor but I asked around and all I did was replace the thermostat, no problem since.

Read more at: https://www.obd-codes.com/forums/viewtopic.php?t=6688
Copyright OBD-Codes.com"

"I own a 2000 Jag S-type w/ 4.0- recently overheated on a road trip. I have changed thermostat, flushed system, properly bled air from system, even pulled internal parts from old thermostat to ensure coolant flow through engine. Still within 10-15 minutes of idle temperature gage shoots to how and warning come on dash. I do not see water in oil and the car runs perfect. The fan comes on when it should and adjusts as the temp increases. Also, as soon as I shut car off, wait 3-5 minutes and bleed pressure off expantion tank the temp is back to normal operating range. Is this a major issue with the engine or is it possible to save without selling my house to cover repairs? Thanks!
...
Ok. I REALLY hope this is a good thing. I took the top hose off at the radiator and started the car.
I didnt get a drop of water from the motor or the radiator. Yes, everything was topped off and there was water in the hose, but when I started the car. NOTHING! Please, please tell me that is a good sign the water pump is bad. Because it is still under warrenty.
...
Yes, thermostat center has been removed. So no flow restrictions are present. Top hose and Manifold were full. No water moved when I started the engine. Called my Jag mechanics this AM. Said he has heard of this in the past but never personally experienced it.
But the pump is indeed still under warrenty.
Thanks for all the troubleshooting help."

"Hi Everyone
I recently had the thermostat and water pump changed on my 97 XK8 to the latest type. I was driving today very slowly and the temperature gauge suddenly climbed up to red and the throttle response felt odd - like it was running out of petrol. I pulled over right away and switched her off. The fans were running so I opened the bonnet expecting to see steam everywhere but the engine was cool to touch on the top and even the hoses around the rad felt cool.
I waited a few minutes and started her up and the engine temp gauge went back to the centre and I got her home (only a mile or so).
If the engine had overheated surely it would have felt and smelled really hot.
The mechanic that did the work is taking a look on Friday and he suspects an airlock could be to blame.
Any thoughts please?.
Thanks
Dave
...
new engine coolant temperature sensor."

"According to the gauge of My 3.0 99 S-Type it comes up to operational temperature quite quickly as it always has and then about 1minute later the rad fan kicks in and it starts to rise to the red very very fast! 30 seconds to a minute and the engines telling me it's about to overheat etc. Even at idle this happens. So I turn it off and pop the bonnet up. The exhaust manifold is Luke warm and the block feels hot but not scolding hot. The coolant which is topped up isn't particularly hot and even the rad is only warm. Within a few mins the fans disengage and the car shows normal temp again... Quick cool down in my opinion?! It's takes ages to cool from operational temp to stone cold so it's odd to me that it's cooling from almost boiling point to operating temp so fast. Starting the engine causes the rise again and within a few seconds it's well on its way to the red.
...
I removed and flushed the radiator, I flushed the block and the down pipes for the resovoir. A bit of sediment but nothing serious. Then I decide to take the expansion tank off (I'm come this far) and in the bottom of the tank part blocking the hole is a very much boiled mouse.... Grim as f**k! Pretty much just a skeleton but enough to block the hole."

 

Hmmm... seems as though there could be a multitude of issues going on here. Either way, here goes:
2002 S-Type, 4.0 with 141K miles. Same scenario, driving fine, then BOOM, straight to overheating. Sometimes, I can throw it in Neutral, rev the engine, and it will go back down. Others, I throw on the A/C and it goes back down. Rarely, if I'm not paying attention and catch it in time, I have to quickly pull over and shut it down. Immediately start it up and it's, yep, you guessed it, back to normal.
My question is, by # of steps what should I try first? I would like to try to eliminate it myself if possible. It's been in the shop for a couple of other things and every body claims to be a jag mechanic but I have other feelings once their done.
I know this is a redundant topic but your help would be appreciated. I always get a Haynes manual for all of our vehicles but can't get anything for this one. I work 2 jobs and don't have a lot of time to go fishing. Any help with a step by step process of elimination would be greatly appreciated.
To note, I have noticed the back up warning doesn't happen anymore and the trunk no longer opens with the interior release. I assume this is some sort of vacuum issue and totally not related.
Much appreciation for your thoughts.

 

Sounds like you have three individual but possibly related electrical issues. None of them are vacuum related.

 

Well that's a start!

 

Download the workshop manual - far better than Haynes.

Stop letting it overheat or you'll need an engine!

 

Any idea on where to start the electrical hunt?

 

Workshop manual

 

Update: Recently put two new tires on the front and haven't had an issue since. Now this is Jersey and it's been a "little warm" so the A/C has been on constant. Really not sure if the problem is solved or not, some how just can't stop constantly checking that temp gauge.........

 

Hey all, we're dealing with the same overheating issue. 2000 S-Type, V8, approx 55k miles. I'll have to verify with garage (it's going in again today) about thermostat housing; I know the thermostat itself has been replaced. I know the timing belt tensioners are metal; replaced them when we first got the car.

Doesn't overheat (I think) if climate control is on, and when it does overheat, turning climate control on seems to immediately (?) bring the temp back down.

What nobody has mentioned yet - does the climate control actually *work*? We get no heat from it (we did during the winter; didn't have overheating problem then). Windshield defroster doesn't work unless the air-conditioning switch is on, also.

Electric fans (on radiator, I presume) run when engine is turned off, regardless of ambient temps. Don't remember ever hearing them before this problem.

Did you all have heat from the heating system?

(btw, wrote down a bunch of suggestions from the 6 pages of messages I'll also go pick up an OBD reader...)
Love the car, but as a mechanic - well, I'm not sure which end of the screwdriver to pick up and hammer things with... Now *software and electronics* - that stuff I'm fine with.

 

I'd start by checking all the temperature etc things via OBD.

Yours would have had a plastic impeller and sometimes they break up so I suppose there's a risk there are parts lodged somewhere.

Fans running on - a sign of car in serious distress, sadly.

 

Replacing temp sensors seems to be the logical first step in a lot of the issues of overheating.
The quality of them isn't great and there is a global problem of poor quality components sourced from cheap suppliers. Toyota have been bitten hard by this problem.
I experienced temp sensor quality issues with my previous car a F*rd. Coincidence? I think not..
Sealing the threads is a good idea to prevent coolant leaking and wrecking the electrical part of the sensor.

My coolant tank cap leaks slightly but doesn't cause any issues (yet).

 

Thanks, JagV8 - when we brought it to the mechanic yesterday the coolant was low (yet again... and I knew it was - didn't fill it so mechanic would see it without my touching things; short drive and I kept my eyes glued to the temp gauge). They said we need a coolant recovery bottle (with cap and hoses). Wife said "do it" so that'll be done today. Crossing fingers that's it, but...

I just ordered a (cheap...) ODBII scanner from Amazon - a few bucks more than the same on eBay, but we'll have it in two days. It's one of the teeny-tiny blue ELM327 Bluetooth ones. We'll see what it tells us...

 

Let's hope it's not one of the bad clones that fail on some cars!

 

(Eeyore voice on)
Oh, I'm sure it will be...
(Eeyore voice off)

Yeah, there seem to be lots of clone problems, and lots of complaints on the 2000 S-Type especially. I got it on Amazon 'cause it's easier to return if it doesn't work.