Heater Plug Thermostart for Perkins Engine 4.212 4.236 4.248 4.318 6.354 6.372++One New Aftermarket Replacement Thermostart Heater Plug for Perkins Diesel Engines This intake manifold thermostart heater plug mounts in the intake manifold and aids cold weather starting on Perkins diesel engines equipped with a Thermostart system. When energized, an internal heating coil warms a bimetal valve that opens to allow a small amount of fuel to combust, heating incoming air for reliable cold starts. Features a screw type terminal and 7 8"