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Cummins N14 – Thermostat Housing – Inspection

Visually inspect the housing and the cover for cracks, corrosion, or damage. Replace the parts if necessary.

Inspect the thermostat seal and the thermostat cover gasket surface for cracks, corrosion, or damage. Replace
the thermostat cover if necessary. The thermostat seal can not be reused. The seal must be replaced if it is
removed from the cover.

Inspect the thermostat for damage.

Suspend the thermostat and a 100° C [212° F] thermometer in a container of water. Do not allow the thermostat or the thermometer to touch the sides of the container. Heat the water.
NOTE: Record the temperatures at which the thermostat begins to open and when it is fully open. Allow several
minutes for the thermostat to react to a stabilized water temperature.

NOTE: The nominal operating temperature is stamped on the thermostat.
The thermostat must begin to open within 1° C [2° F] of nominal temperature.
The thermostat must be fully open to at least 9.5 mm [0.375-inch] within 12° C [22° F] above nominal temperature.
Replace the thermostat if it does not operate as described.

Measure the inside diameter of the thermostat seal counterbore in the thermostat housing.

Use a depth micrometer or a depth gauge, Part No. 3823495, to measure the depth of the seal counterbore in
the thermostat housing.