2007 4.2 NA V8

Here’s a weird one. I noticed I’m leaking some coolant. Looks like it’s coming off the front of the engine somewhere. From above I can’t see the source of the leak. But what’s odd is I’ll drive the car and park and nothing is leaking. Check back an hour later. Still dry under the car. Come out the next morning and it leaked a puddle of coolant overnight. So it’s like it doesn’t leak except while the engine cools down and it doesn’t do it every time. Occasionally I’ll park overnight and it remains dry under the car.

I only noticed this going on after I took off the plastic cover under the engine to do my idler pulley replacement and left the cover off. Chances are the car has been doing this for longer than I realized.

I got a low coolant warning from the car a week or two ago. Got some orange OAT ford/Lincoln coolant and topped the tank up to the “min” level. It took about 300 miles of driving to get back to the low coolant warning.

my top suspect would be the water pump just since it seems to be dripping down the front of the engine by the oil filter. But I can’t say I can actually see it leaking. Thermostat assembly looks dry all around. What do y’all think? Is this behavior indicative of anything in particular?

 

After a cold soak, preferably overnight, use a cooling system pressure tester to pressurise the system to 1 bar. If the gauge on the pressure tester begins to drop, inspect the engine compartment for leaks.

Two known failure points are the water outlet that contains the thermostat, and the hoses to the egr valve that run under the inlet manifold.

 

System needs to be pressure tested. Water pump weep hole is a likely suspect. My leak issues started with a crack in the radiator's plastic side tank. Check out my cooling system overhaul in my sig for the full horror story.