My 2001 Jaguar XJ8 Vanden Plas has a pretty fast coolant leak. I'm no longer driving the car. Can't see the leak from the top. As soon as you fill the reservoir you can see it leaking at the rear bottom side of engine. A very steady drip. Sorry in advance for the terrible videos. I used my phone in plastic wrap attached to a 2x4 lol. Any advice on what part it may be would be appreciated! Thank you!

Links to both videos:

 

There are 2 hoses that run underneath the intake manifold. Heater supply and Heater return. Most likely one of them is leaking if the water appears to be on the right side of the engine. Left side is the octopus hose and norma connector also known leak points.
If you pull the engine plastic covers off you will have a better chance of pinpointed the culprit.

 

Like avern said, there's two heater hoses under the inlet manifold. It might be hard to tell exactly which one is the culprit, but either if you see coolant on the sides the plate between the "V" of the engine, then it's most likely one of those hoses. The picture below shows the red arrows pointing to the two heater hoses, and the orange part is where the coolant will most likely be sitting if either of those hoses fail.

 

Thank you for those who responded to the initial post! I did a little more investigating and lo and behold...I found the leak! There was a constant spray coming from a brittle non return valve, part of the "octopus hose". Thankfully the part that was leaking was able to come off, attached to two hoses with hose clamps. However, I've noticed another very small leak at the coolant reservoir. It appears to be leaking right below where the coolant level sensor plugs in. I swapped the sensor with one from my parts car and still the exact same leak. It's very slow, but constant. Has anybody had any issues with it leaking coolant in this area? Should I just swap the entire reservoir? I've attached a video of the drip below.

Thank you!

 

The level sensor does not actually seal the point of its insertion into the tank bottom; it is just clipped there and sits inside a closed plastic tube which is integral part of the tank. You need to replace the tank as it has a crack in this area.