NOTE: If the plunger of the pressure tester is pressed too fast, an erroneous pressure reading will result.
6. To pressurize the engine cooling system, slowly press the plunger of the pressure test pump and increase the pressure to between 124 - 138 kPa (18 - 20 PSI). Observe the gauge reading for approximately 2 minutes. Pressure should not drop during this time. If the pressure drops within this time, inspect for leaks and repair as necessary.
7. If no leaks are found and the pressure drops, the leak may be internal to the engine. Inspect the coolant for engine oil and the engine oil for coolant. REFER to: appropriate Engine article.
8. If the pressure does not drop remove the cooling system Pressure Tester and adaptor from degas bottle.
9. Install the degas bottle cap until it contacts the hard stop.
Thermostat
Install a new thermostat only after at least one of the following tests and checks have been carried out:
Pinpoint Test B or C
Thermostat Visual Inspection
Thermostat Visual Inspection
1. Remove the thermostat.
2. Examine the thermostat for signs of damage including:
Valve not fully seated (light visible through the valve)
Foreign material lodged in the main valve
Bent or broken frame or flange
Bent or broken spring
Wax leaking from wax reservoir or a bulge in the reservoir
Any other damage or distortion
Original technical text and illustrations, formatted as HTML. Follow the engine, transmission, equipment, model and year specified in the source. Import and layout checks do not establish applicability to every 2015–2017 Mustang. About this collection.