2006 Ford Mustang v6 possible coolant issue

I have a 2006 v6 ford mustang and just developed this problem yesterday.

When I drive the car, the temp guage stay right in the middle, but when I park I get white smoke come from under the hood. I popped the hood and saw coolant leaking from where the top radiator hose meets the engine block. This was producing the smoke. When I checked the hoses, the top hose was hot and hard, the bottom hose was cool and soft.

Extra info:

  1. I did not touch the radiator to see if there were cool or warm spots
  2. The overflow bottle looked empty or close to it, but the engine was still hot from driving to work

Thinking this could be one of the following

  1. bad thermostat
  2. clogged radiator
  3. Air bubble somewhere blocking the coolant flow

What do you think the problem is?

More than likely it’s the thermostat housing leaking and it’s a common problem.
You will need the housing, a new thermostat, and even a new ECT (engine coolant temp) sensor.

The use of plastic in an area where it should not be used is the root cause of the problem and the reason for the new ECT sensor is that Ford, in their infinite wisdom, chose to provide a different thread fitting on the replacement housings. This means your old ECT won’t fit the new housing.

You are low on coolant for sure. When the engine cooled down, did you open the radiator cap and add coolant?

One morning before driving the car top off the radiator and take the car in for a cooling system pressure test. The problem will be easily found. As ok4450 said, more than likely they will find a leaky water outlet/thermostat housing. I’ve seen this on yours and other Ford engines as well. Have this fixed before the small leak becomes a complete coolant loss stranding you on the road.

Any local reputable independent garage can take care of this for you.

I meant to add that I agree with OK4450 as to the root cause, but when you saw steam, the coolant level was low at that time.

If you car has a radiator coolilng fan, is it spinning like a banshee when the car is idling and the steam is coming out? It should be.

In any event, it’s very important to monitor the coolant temp gauge until this problem is resolved. Any sign of engine overheating, pull over and have the car towed. In an emergency you can usually get some engine cooling effect by turning on the heater to max and heater fan to max.