I just picked up a cheap 2006 with 4.4L. I noticed a coolant leak and when I pressure test it, there is a steady stream of water coming off the rear of the skid plate. I removed the skid plate and see it's running down the bell housing, but having trouble tracing it "up" the rear of the engine.

From the top, all hoses (especially heater) seem fine. I can hear some hissing and see bubbling from what I believe is the thermostat housing (huge chunk of black plastic at the front of the engine...seems like a crossover pipe of sorts). The leak is coming from under the throttle body, so it's difficult to tell exactly how much it's leaking. Is it possible this is pooling up on top of the block (under the intake manifold) and running towards the rear? It also looks like the heater hoses have a "run" that goes down the back of the firewall and behind some heat shielding, but this doesn't seem to be in the area of my steady stream of water. I'm gonna start with this big housing, but any other thoughts or common areas to check? I'd like to order all the parts at once...

 

The crossover housings tend to eventually fail. Especially if not OEM. Probably cracked and running down the valley under the intake and down the back. There is also a small coolant hose right under the throttle body that loops back to the front. Mice can get to it and chew on it. IN the second pic below, you can see the opening in the aluminum. The hose is right behind there, you can barely see the clamp but the hose on the left is the same hose. Tricky to replace. You pretty much need to remove the throttle body to investigate.

 

DakotaTravler: Do you have a part number for this hose?
I need this replaced on at least 2 LR3's in our fleet and have been too busy (lazy?) to do a parts look up.