95 mustang leaking coolant behind water pump.

Coolant Leaking Behind Waterpump

95 mustang v6 leaking coolant behind the new water pump. worse when turned on. does not appear to be the pump or any hoses.

Solution:

If the leak is behind the water pump , then either the new water pump gasket is leaking or the timing cover from the timing chain that the water pump bolts to is leaking and the gasket between the timing cover and the engine block.

A couple of the water pump bolts are actually studs that go through the timing cover to the engine block. When the nuts are loosened, the timing cover also loosens. If the gasket for the timing cover is close to failing, it will start to leak. The reason it doesn't leak much with the engine off it because the water pump is not running and no real pressure is on the system. When the engine is running, the cooling system builds up pressure, usually 16 psi and it will push through a weak gasket.

I think it is just in need of a new gasket at 151000 miles. The bolts will really go in one way and the nuts on the studs will tighten up when in the correct place. If you removed the studs, then the gasket is in need of replacement.

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PROBLEM 2:

Now it idles smooth. Seems to have all the air out of the coolant lines. BUT when I drive it, it runs with the temp gauge to the red, then cools off to the center, then back to almost the red. The only time the heat kicks out hot air (heat on the whole time) is when it gets to the red and immediately goes to the center. At this time, it runs rough. After it cools off, it idles great, runs great for a short while. Think it is a head gasket?

There should be a bleeder cap bolt located on top of the engine near the front of the intake.It is right above the thermostat on the intake manifold.

There should be a bleeder cap bolt located on top of the engine near the front of the intake.It is right above the thermostat on the intake manifold.

graphic

When the engine is cold, remove the bleeder bolt and fill the radiator with coolant till the coolant comes out the bleeder opening. Then reinstall the bleeder bolt and start the engine. Let it warm up and then loosen the bleeder bolt, do not remove it, just loosen it and let some coolant come out and then close the bleeder. Top the coolant off and drive the Mustang.

The problem you have is an air pocket in the cooling system.

Thermostat Operation:

The automotive thermostat is a temperature controlled on and off valve. When the temperature rises to a predetermined temperature, the thermostat opens up to allow the engine coolant to flow through the cylinder block and the radiator. This flow is crucial to maintain optimum operating temperature for fuel efficiency, enhanced driveability, and engine protection. The coolant flow is reduced when the engine is cold, and the flow is increased when the engine is hot. Contrary to popular opinion, operating the vehicle without the thermostat doesn't make the engine run cooler. It will actually run hotter because there isn't a thermostat to slow the coolant flow. This means the coolant doesn't stay in the radiator long enough to dissipate its heat.

Coolant Temperature Sensor Operation:

This sensor monitors the temperature of the engine and sends that information to the engine control computer to regulate the amount of fuel needed. More fuel is needed if the engine is cold; less if it's hot. If the temperature is extreme, the signal will be sent to the temperature gauge as a visual indicator of overheating and imminent danger.