Hello everyone,

I am the proud new owner of a 2003 Jaguar S-Type 2.5 V6, 330 000 km but has had the same owner for 17 years, regularly serviced and rust-proofed when new. However for the last week I have been leaking coolant 500 ml/30 km and from reading the various posts around these forums I am thinking that the coolant reservoir has cracked, especially since I am not sure if it has ever been replaced. I have taken some photos of the coolant drip, I would like your thoughts about if you agree with my suspicion, it seems like it leaks coolant from the bottom hose. No visible coolant under the car, no white smoke from exhaust or white sludge under oil filler cap.

 

After an overnight cold soak, use a cooling system pressure tester to pressurise the system to 1 bar. If the pressure indicated on the pressure tester gauge begins to drop, search for leaks around the overflow reservoir and hoses.

 

Looking at that last picture, I would also have a look at the DCCV; that looks quite corroded.
Not sure if that is causing you problem or maybe result of.

 

Everything is very old and ready to fail. I would replace ALL the cooling hoses and that terrible looking DCCV too.
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So the cooling system on this car has a lot of weak spots.
i can see the DCCV is red so i assume the leak happens at the oring where the elbow connector meets the expansion tank.

known weak spots on this model:
-radiator (plastic sides crack easily) and bottom alu melts
- engine top alu elbows and Y piece orings
- engine too elbow to water pump Rubber Elbow
- plastic junction where the temp sensor is
- DCCV or its hoses

 

If you want to see if cracks in the reservoir leaks, check it out when running. The pressure opens up the cracks enough to leak, it happened with my car before. If you want to check joints for leaks wrap a paper towel around it and see if it gets wet after driving a little bit. If the reservoir is cracked, you can patch it with aluminum tape when the engine is off and cold. It will keep the cracks from spreading, until you get a new one. If your cap isn't releasing pressure, it will ruin everything, have it checked out. A few years ago I replaced my stock 20 psi cap with a 16 psi cap for a modern Thunderbird. With less pressure, things last longer and the car runs fine.

 

I had this with my S-Type when I bought it and it took me ages to find the culprit. In the end I found that there was a pinhole leak in the radiator, which was causing a jet of coolant to spray onto the belts, which in turn caused the coolant to spray out into other parts of the engine bay. I ended up with a sutiation that looked basically exactly like the photos above, which is why it took me a while to realise it was the radiator. To look at where the coolant marks were, I really thought it had to be from the reservoir or something around that area. Alas, a new radiator was the fix for me!

 

I hope that when you replaced the radiator you also replaced the old water pump when everything was wide open. When I replaced my radiator I didn't do the water pump and two weeks later the water pump started leaking like a stuck pig. At least removing the fan and shroud was easier the second time around.

 

500lm/30Km? You wlll be able to spot that if you look. The DCCV as others have side is leaking but not to this extent. I would have a look at the bottom of the radiator, and under tray.
Being from Finland, Salt, Cold etc.

 

Thanks to all who replied to this thread, this issue has now been resolved. I took the car for a pressure test and it was actually the water pump that was leaking, a new water pump has now been fitted by a local garage who also checked that there are no other leaks and that all the hoses look good. I am still waiting for an OEM auxiliary belt since the one I ordered from my usual parts store was way too short in length, once that arrives I will have that changed also.

 

I had several coolant leaks - and one was on the water-pump (of my 2004 S-Type) - see the fifth picture in:
https://www.jaguarforums.com/forum/s...aks%94-263540/

Well, actually the leak was not on what is being sold as "water pump", but on the back-plate of the water-pump, which is missing, when you buy a new water pump... And normally there is no way to buy that back-plate - but I found some...