Only beefs I have ever had with my 03 S-Type are the typical need to replace the window regulators a couple of times (grandkids necessitate that) and the radiator overflow tank - 3 times.

Now I have a problem.

In July, 2013 I took it to a dealer because of a very, very slow leak - a cup of fluid every couple of thousand miles. But then it began to blow pure hot air out the driver side vents with the a/c on, so I took it in.

Diagnosis: Replace radiator expansion tank (C2Z13764 - $116.00) (probably not necessary); heater control valve (XR840091 - $307.00) and a Module - Air Conditioning (XR840134 - $1,420.00) - total Invoice $2,838.07.

Left the dealer and by the time I got it home (approx. 80 miles) I could still smell the antifreeze but the service rep said that should be expected until it all 'burns off'.

About a month ago (I drive this car perhaps 150 miles a month) the Low Coolant light starts blazing. Added a cup or so of fluid. Couple of weeks later same routine. Couple of weeks later it is every time I drive it more than 5 or 10 miles. Starting last week, every time I take it out, the warning light goes off and I have to add more fluid - much fluid. Can't see a leak anywhere. No dripping water. No puddle. No water signs under hood? WTF?

Back to the dealer. They can't find anything. Pressure is correct. Dye does not show anything. Etc. Does not make sense?!? Keep driving it until something shows up.

So, I get online and see all over the place that there was/is an issue with the thermostat housing. I spent the last couple of days trying to track down a new housing and finally 'learned' that my engine is the V45255 series.

I pulled off the engine cover to see what would be involved in the replacement, as I am at least quasi-mechanical. What do I spy, but the attached photo.

The leak is in the casting seam in the piece directly behind the thermostat and I assume, from this image I captured somewhere on the web, that this part is called the 'water outlet pipe'. It must have been a pin-hole leak just waiting to expand, as now it is quite a 'squirt' of fluid.

Does anyone know if this is a significant repair that requires dealer know-how and tools or can the average weekend mechanic tackle this replacement??

Thanks

 

Pretty common failure and many DIY guys have changed it. Just be aware that the car is now over 10 years old and ALL the plastic will be weak and decayed.

Do some searches for instructions and for other parts to change at the same time. Kind of surprised the dealer did not find it because as I said it's a common failure.
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Intake manifold and you will have room to work on it....also recommend doing the water pump since you are there and you can get them cheap

 

If you don't want to DIY, then it also doesn't have to be a dealer. Any mechanically-competent shop could do it. Main thing is to top up after with the right kind of coolant (because the wrong stuff gels and blocks everything up).

 

I've actually been searching, unsuccessfully, for an engine diagram of the 4.2 on an 03 V45255 - and/or a Repair Manual/Shop Manual. Seems like they are non-existent.

Have rebuilt, from frame up in most cases, the following vehicles in my hobby lifetime, but it's been quite awhile since I was 'mechanical' with an automobile. Just tossed out my timing light, dwell meter, gauges and other 'antique' gear a couple of weeks ago!

The 2003 Jaguar S-Type 4.2 that I am in the process of 'pickling' for my 7 year old granddaughter is probably going to be the most fun - but I am going to be at a loss for most of the 'under bonnet' work. To me its' just the lines and look that the overall vehicle has (forgiving the Ford Taurus twin rear-end), but when the BRG has been freshly Meguiar's-ed, it sure gets a lot of comments from connoisseurs of classic cars! Has around 42k highway miles and average 30 to 32 mpg doing so! Car seems to cruise at 70 to 75 mph at around 1,800 rpm.

My Rebuild History/Memories - in the best order I can recall:

1959 Buick Electra
1964 Olds Cutlass F-85 convertible (most Fun car I ever owned/drove)
1947 Packard Clipper Flathead 8
1947 Buick Deluxe flathead 8
1947 Packard Clipper Flathead 8 (2nd one)
1964 Buick Riviera
1967 Buick Riviera
1971 Buick Riviera (Boattail) - perhaps the 2nd best car I ever owned!
1977 Porsche 924 (fun to drive but problems, problems, problem - VW engine)
1962 Corvette convertible (what a truck it was to drive)
1964 Olds Cutlass 442

Addendum:

LOL - you should have been a fly on the wall when I began negotiating for my new 2014 XJ BRG RWD - 550 hp and they told me it would be another $800 to put the Jaguar Leaping Cat Emblem on the hood, which I am insisting on, at No-Cost! My wife walked out in embarrassment [she claims] and I ended up doing so as well - but they called me back!!

 

The factory manual is called the JTIS. It's free on this site. Just look at the top of the threads and look for something with JTIS in the title.
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