Nearly all coolant lines, hoses, pipes, tubes, water pump have been replaced on 2015 Discovery (LR4). Today parked after a long drive and upon returning to the truck, found a very large pool of coolant in front of and underneath the front end. Washed every down and refilled with fresh coolant. Ran engine for a while and saw no leaks. Went for a long drive and still no leaks. Parked for a bit and it leaked again. Repeated the wash down and refill, drove for a while, no leaks. Went for a very long drive home, parked and within minutes coolant began leaking. From the top the coolant appeared to be leaking from below the flywheel. Removed rock plates and had a look. All hoses and fittings appeared fine but coolant appeared to be steadily leaking from the bottom of a thin black metal plate located on the engine and behind the flywheel. Pardon my ignorance, any thoughts on what this could be?

 

Since you said it's leaking from the front, when you say "flywheel" I'm assuming you mean the balancer (the thing with the belts on it). That metal plate is the timing chain cover. The leak might be from the water pump. The water pump sits directly over the timing chain cover. A leak from the water pump would probably run down the front of the block along the timing chain cover and drop off at the bottom, making it appear like it is coming from behind the plate. Check your water pump.

P.S.- since you're poking around the cooling system anyway, maybe you could help me out. Please check out my post about a coolant line/fitting I'm trying to identify.

 

Well the pump's less than 2 years old AND my over confidence convinced me the leak, despite the lack of any cooling circuits in the area, could not be the pump... Managed to get a camera under the pump and..... indeed there's a trickle of coolant under the pump pulley...@*#&$^%!

 

So, I replaced the pump, the tube and o rings, all oem, along with 2 new belts (only 3 years old but main dealer recommended doing them), and some more tubes and hoses. IT was a very easy job to do, fan comes out easily leaving massive amounts of room to remove tensioners, belts, hoses and pump.

Put it all back together and topped off cooling system and bled with the 3 bleeders. I didn't feel much coolant had been lost but after running the engine for a bit I got the over temp warning and turned off engine. Bled some more and let it sit. Filled with about a gallon of coolant and ran again, this time I got engine under temp warning. No leaks apparent anywhere. Also note with climate set to max heat, the air was still cold. Got a vacuum out and vacuumed the system until hoses were flat and more air bubbled out of expansion tank. Note there was a faint hissing noise from the area of the water pump. Topped off coolant again with about half a gallon. Note coolant was lost during the initial bleeding process. Ran engine again and no more temperature issues EXCEPT now, while the engine was running, coolant was streaming from the bottom of the water pump!!!!!! Remember the leak I was fixing only happened with the engine off, if the engine was running, I could drive 100 miles with no leaks., now it's leaking while running.

Ideas????

 

the only thing I can think of is a leak on the backside of the WP where the intercooler connector is. That fitting/o-ring may be leaking.

 

That's what I think too but how can you tell? I used a camera and I see about a 1/4" gap between the water pump outlet and the outlet tube half moon shape, shouldn't that be flush? The outlet tube nestles in a crevice on the left side of the engine block.