I had a similar situation this week on my 2000 Frontier 4 cylinder. The leak was near and under the front of the intake manifold. Let me say what helped a lot was ordering a MIGHTY VAC COOLANT PRESSURE TESTER from Amazon for like 36 bucks !!! It turns out there are 4 coolant hoses under the intake manifold. The most common one to leak is a U-shaped hose that Auto Zone calls a "bypass hose". Visibility and access are achieved by unbolting the power steering pump (and laying it back without disconnecting the hoses), the cast iron pump bracket to the head, the battery, and the upper hose. There is another straighter or "dog-leg" hose that is helpful to remove (and replace) at the same time). With those removed, there is JUST enough room to access that U-shaped hose without removing the intake manifold). The Auto Zone part number for the Dayco hose (which they stock) is B88354. The beauty of having the pressure tester is that you can simulate hot driving pressures without heating up the engine AND you can quality check that the leak was fixed BEFORE finishing all the reassembly. You can also borrow pressure testers from Autozone and Oreilly, but the deposit is pretty hefty (of course, you get it back if returned in 48 hours). Hope this helps someone !!!!