How to Install an Engine Water Temp Gauge

by David Young
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car dashboard displays image by TekinT from

An aftermarket temperature gauge can be installed as a supplement to or replacement for the existing temperature indicator in your vehicle. Many new cars use high and low temperature lights instead of traditional gauges. While the lights will alert you to dangerous temperatures, they do not provide information about the operating temperature of the vehicle. Adding a temperature gauge will allow you to monitor the temperature of your engine under different conditions and can give you an early warning of potential problems.

Step 1

Choose a location for the temperature gauge mounting hole on the vehicle dashboard. Ensure that the gauge will be visible and that no wires or hoses behind the dash will be damaged when drilling the mounting hole. Use a drill and hole saw to make a 2 1/16 or 2 5/8 inch hole (depending on the gauge model) in the dashboard at the chosen location.

Step 2

Drill a 7/8 inch hole in the vehicle's firewall. Ensure that there are no wires or hoses behind the firewall that could be damaged by drilling. Cut a slit in the side of a 7/8 inch grommet and slide the grommet over the temperature sensor tube. Slide the sensor through the mounting hole and through the hole in the firewall. Install the grommet in the hole in the firewall.

Step 3

Slide the temperature gauge into the mounting hole. Place the included bracket over the mounting post on the back of the gauge. Place the lock washer over the post and install and securely tighten the knurled thumb-nut onto the post.

Step 4

Connect one wire from the gauge light to a grounded metal part of the vehicle chassis using an existing bolt or self-tapping screw. Connect the other wire to a positive (+) 12 volt wire from the dashboard lighting circuit using a wire tap-splice. Clip the gauge light into the hole in the back of the temperature gauge.

Step 5

Route the temperature probe through the engine compartment to the existing temperature sending unit mounting location. Avoid running the tubing near moving parts or exhaust components. Remove the existing temperature sending unit with an open-ended or adjustable wrench.

Step 6

Wrap two layers of teflon tape clockwise around the threads of the included mounting nut. Screw the mounting nut into the temperature sender mounting hole and tighten securely with a wrench. Insert the temperature probe into the mounting nut and tighten the sealing nut securely into the mounting nut with a wrench.

Step 7

Start the engine and check for leaks and proper gauge operation. Recheck and tighten all connections if leaks are found or if the gauge fails to operate properly.

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