Hi All
Regarding the overheating issue: I had this problem in April 2013 on my Dec 2000 4.0 V8 at 145000 miles. The usual trick of Putting on the heater worked with regards to stopping it on the spot. I got fed up with doing that, so had had the temp sensor replaced (matter of caution) and a new coolant tower cap fitted(cap was cracked so was likely root cause). The problem went away for 14 months (no issues at all) until today, at 157000 its done it again after a very short run - less than 3 miles!! I've just topped up the water and will see how things go! Will check cap for cracks when I have good light.

Cheers
Paul

 

Hello to all of you, I'm a newbie from Germany so my English is not even good as yours. I'm sorry for that :-)

I have a really nice '99 Jaguar S-type 4.0 V8. Actually 96.000 miles.. I bought it last year and it runs perfectly until the "overheating problem".

Things I have already replaced:
-Thermostat (was still intact)
-Watterpump(was still intact)
-ECT Sensor(think old one was still intact, too)

After all these replacements nothing changed. On first day of overheating the temp gauge went straight to Red zone, after changing these parts an bleeding the system, the temp gauge stays in the middle (heater in cabin on HIGH) but the fan is running on max speed. I think the car don't loose coolant and as I can see everything looks perfect.

I think there must be air in the coolant system because the overheating is not so bad as before I bleed the system.

Another thing that I think is not normal:
Before I changed the Watterpump, I have tried to drain the system(drain plug on the bottom of the radiator) i opened the drain plug and the expansion tank cap but only about 2-3 Litres of coolant came out, no more at all... Is this an indicator for a blocked coolant system? For example a blocked radiator?

The S-type is such an nice car but the technic is so complicated Now here in Germany the sommer is coming so it would be nice to solve the overheating Problem asap. Every help would be nice:-)
Thanks in advance and greets from Germany

 

Use an OBD tool with live data. What value does ECT have when engine is hot? What maximum value as you use the car?

 

Did you check the auxiliary pump?

 

Thanks for your quick response!

I have an obd tool that can check live data, I will do this tomorrow at my garage and let you guys know what results I got.

When I put the key to ignition and open the hood I hear a slight buzz, I think this should be the auxiliary pump, am I right?

 

After one hour on the highway I checked the temperature with my obd tool, temperature was at 221 'F. The Fan was as always running on max speed!

Thanks

 

That looks too hot. If you used the correct thermostat and did not fit it the wrong way round - it's possible! - then I think you need some urgent fix but I'm not sure what. The aux pump, maybe.

Another way a car moves heat around is the engine oil and that means:
having enough
the right kind
the correct oil filter

in case you have a fault in one of those.

 

This problem sounds like it needs a compression test on all cylinders.

 

So guys, I know this is an old thread, but I am having the exact problem as described. It has been going on for a couple of months. I have not done anything yet and am wondering where you guys think I should start... Should I take it to the dealer and have them run a diagnostic (It's about $125)? I hate to start replacing parts for naught... Any advise would be helpful, thanks. I don't have an obd tool, and really don't want to buy one. Although I can replace most parts, I don't have the time to spend trouble-shooting.

 

Is the MIL on? BTW OBD tools start at under $10

Does your engine fan work properly (e.g. when it should)? Have you changed the thermostat? Expect overheating if not.

 

Then I see many tears in your future. Paying a mechanic is frequently much cheaper than guessing which component might be at fault.

 

That just doesn't make sense unless you are happy to pay someone to do it for you.

 

OK, OK, I'll go out and get one...

 

The MIL is not on. The fan works fine. No, did not replace the thermostat (but I have not seen anywhere that replacing it solved the problem).

 

Water pump replaced? Had it broken up (as they're prone to do with age)?

With no MIL and your description I suspect OBD won't help - though the tool is very cheap.

 

Replace the thermostat...it is cheap and easy and a sticking thermostat is most definitely a common problem. If that does not solve it, consider it good preventative maintenance and inspect the water pump next. And do not drive the car until this is fixed, it puts tremendous stress on the engine.

 

Hello. This has been a great informative thread. I just got a 2000 S-Type 4.0. Love the car, but it overheated for the first time yesterday. Like a few others here, I parked the car and let it cool down then turned on the heater and the temperature needle went back to center.

This car has the metal thermostat housing but I'm not sure when it was replaced. It sounds like these never were built this way in 2000. The coolant level is extremely low and I can see a small pool of orange coolant right under the thermostat housing. ( Is it the water pump that is directly below the housing?)

I'm not driving the car now but I'd like to top off the coolant and see how bad the leak is. When I got the car I didn't check the coolant level so I don't know how long it has taken to get down to its current level. What kind of coolant have members been using and recommend?

 

I would use the factory recommended coolant. On my 2005 STR that is Dex-Cool.
.
.
.

 

Thanks. I did find that after browsing around. Still very new here. Thanks.

 

I got anti-freeze from O'Reilly. Their book on my 2000 4.0 says ZEREX G-05 non phosphate. The numbers do match my owners manual.