Nissan Z - ZX 1970-1988 Repair Guide

Manifold Heat Control Thermostat


See Figures 1 and 2

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Fig. Fig. 1: Typical manifold heat control thermostat

This device is installed on 1970-72 models, to heat the manifold during engine warm-up. Engine coolant passes through openings in the manifold until the temperature reaches 150°F (65°C) exists. At this point, the thermostat closes off the flow of coolant through the manifold.

To test the thermostat, remove it and attach a length of rubber hose to the inlet end. Then immerse the thermostat in water heated to 175°F (79°C). After the thermostat has had a minute or so to reach the temperature of the water, force air at low pressure into the hose. If bubbles come out the other end of the thermostat, replace it.

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Fig. Fig. 2: To test the thermostat, immerse in heated water