The LT1 and LT4 crate engines have no provision to add a coolant temperature sensor like the LS series does. GM uses a CAN bus called GMLAN that communicates information from each of the various engine components using packet data similar to IP packets in a computer network. Similar to a train pulling a number of cars around in a circle, the packet data for each sensor rides in it’s own car delivering the data at the appropriate moment needed.
Unlike previous generations, the LT is the first engine in which the water pump is no longer in the center of the engine as shown above. There is a coolant temperature sensor, as seen above on the top right, but I have been advised by GM Performance and Powertrain not to tap into the signal for fear of reliability issues within the packet data stream used by GMLAN (CAN BUS). Since I am not using the radiator coolant to cool the oil cooler, I chose to cut off the end of the stub and plumb in a conventional coolant temperature sender.
Using a 1/4″-18 NPT tap, I threaded in a coupler and then added the sensor. This serves two purposes, one it plugs the fluid passage and adds the sensor in a convenient location without having to weld in an additional bung. Make sure you get the appropriate sender for the gauge manufacturer that you using because there are many different types. Also make sure you bench test the sender before installing.
Here’s the water pump reinstalled with the coolant temperature sensor pointing straight down.