Hello, I have a 2006 Jaguar S-type 3.0L V6 with 83,000 miles on it. It has a coolant leak and I'm in need of an underhood diagram or something to the effect of an exploded diagram of components under the hood. Please forgive me, I've done basic work on cars but nothing really this in depth. When I turn the car on and have someone press the accelerator I can see the car "spitting" coolant from behind the timing belt "cover". I will attach pictures but will also try to explain a little better. I have removed quite a bit of the radiator hoses, the coolant reservoir, engine cover, and the front "air scoop" that leads into a large tube underneath the air filter. I can see the wet spot if I look below the lower radiator hose, underneath the top of the engine right behind the top-most "pulley/wheel" in the belt system. After looking at the pictures, I feel fairly certain that the leak is coming from one bolt. Can anyone tell me what that bolt goes to? The pipe in the picture above the belt is where the lower radiator hose attaches. Thanks in advance for any and all help/advice.












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A slow dripping hose can cause the bolt to appear like it leaking. From the angle of the photos it appears the hose could drip right on the bolt. Reassemble, add coolant dye to coolant , and check for leak with a black light. On reassembly replace all pinch clamps with screw clamps.

 

Like this?

 

I too suspect the hose was dripping. IMO... get a new hose, use 400-ish grit sandpaper to clean the metal hose connection surfaces (only hand pressure and make smooth), install w/a new clamp (old screw type clamps may not give a uniform tension. If it is the constant tension type of clamp just reuse)

IMO.... you don't need to add dye. I'm pretty confident its the hose connection.

While your in there I'd check the DCCV valve. See if there is evidence of it dripping too. https://www.jaguarforums.com/forum/s...ol-how-185002/

 

My reason for thinking that it's not in the hose is because when I press the accelerated you can see the coolant/water squirting toward the front of the car. Could this still be possible with a bad hose connection?

 

Have you considered a cooling system pressure tester? It looks similar to a bicycle pump and connects in place of the reservoir cap. You manually pump up the system and then watch the gauge. A rapid drop indicates a leak, of course. And then look over the system for any leaks.

The big advantage is you can test the system with the engine off. No fan to blow the coolant around and mislead you. Best of all, you can build max pressure, which helps find smaller leaks. Just running the engine at idle barely builds any pressure, so it's easy to miss smaller leaks if not using a pressure tester.

Some auto parts stores have free loaners, too.

 

DO NOT use jubilee clips or screw type clamps to secure cooling system hoses to plastic components as they cause the plastic to fail. Use constant tension clamps, or reuse the factory clamps.

After a cold-soak, preferably overnight, use a cooling system pressure tester as Karl recommends to find the source of the leak(s). The upper radiator hose is prone to failure around the bleed fitting.

 

It's possible... like the others suggest a pressure test kit would allow you to observe it directly.

 

I forgot to mention another huge advantage of a pressure tester. With the engine off, you can really get your nose in the suspect area to investigate. Not possible with pulleys and belts moving, where you must keep a distance for safety.

A small inspection mirror will help, too.

 

What does that bolt go to???? If it is the water pump, the housing could be cracked or the gasket damaged.

 

I was thinking the water pump is leaking. When you rev it it spits. Either from the bearing seal or the weep hole (if there is one)

 

That is possible. If the bearing has axial end play..the rotating face seals can separate during sudden rpm changes. (usually only happens in cold temps though)
(I was a water pump engineer back in the 90s)