Engine coolant leak?

BRUCEVOYLES

MEMBER
2006 FORD MUSTANG
48,000 MILES

I have a 2006 Ford Mustang (V6) with 48k miles. About two months ago I started having coolant spill out of the reservoir through the cap. It only happened with the air conditioning running. I had it worked on and the mechanic found that the low side of the fan relay wasn’t functioning so he replaced it. Drove the car two weeks and the problem started again but know it occurred when the air conditioning system wasn’t running. Took it back and the thermostat was replaced and a new coolant cap was put on. Now I have driven it a week and found that it started again. The gauges in the car are fine and the car doesn’t appear to be overheating. Any suggestions or help would be appreciated.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

More than likely we have an air pocket in the system. We need to start with checking for leaks in the system and that is internal and external. We do this by pressure testing the system.

Here is a guide that will help with doing this. Basically it should hold pressure for hours:

https://www.2carpros.com/articles/radiator-pressure-test

If there are no leaks then we need to fill the system and run the engine with the front corner closest to the reservoir jacked up. This will help work the air to the highest point and it will come out of the bottle.

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

Once we confirm this is not the issue we can move on but if it holds pressure then there are no leaks and I am sure you will find there was air in the system.

Thanks