Weird Coolant Leak

[Traveler]

I've got a coolant leak that just showed up. Its odd in that the coolant appears to stay in the truck, and works well, until I remove the coolant recovery tank cap (Only access to the coolant system). It then starts to leak from somewhere on the back of the radiator, on the drivers side. Its hard to tell precisely where its coming from as its behind (or below) the shroud. I'll then replace the coolant, and all appears great until I remove that cap again.

 

[99WhiteC5Coupe]

I've got a coolant leak that just showed up. Its odd in that the coolant appears to stay in the truck, and works well, until I remove the coolant recovery tank cap (Only access to the coolant system). It then starts to leak from somewhere on the back of the radiator, on the drivers side. Its hard to tell precisely where its coming from as its behind (or below) the shroud. I'll then replace the coolant, and all appears great until I remove that cap again.

I had a leak on my 2015 Expedition Limited that the “factory trained technician” at my local Ford dealer could not locate.

Several checks and attempts to locate finally determined the coolant reservoir was leaking where there was a reinforced metal nipple inserted into the jug near the bottom and where the hose connected to it (which runs to the radiator).

Movement would cause the intermittent leak, which would cause coolant to run down the hose. Replacement of the jug and hose eliminated the leak.

This was one of several leaks repaired under my extended Ford warranty, including the water pump (two trips to the dealer to diagnose that also).

 

[Trainmaster]

Its odd in that the coolant appears to stay in the truck, and works well, until I remove the coolant recovery tank cap

Removing the cap breaks the vacuum and the leak flows. Probably your radiator. When it's hot and under pressure the coolant flowing out of the leak evaporates before it hits the ground. When it's cold, the lack of a vent keeps it from leaking. Pressurize the system and you'll find it.