Installing a Boost Gauge on a GM Duramaxby Francis Walsh
Diesel engines equipped with a turbo charger are asked to perform better than their unequipped brethren. With the addition of air boost pressure from a turbo charger, diesel engines like the GM Duramax produce more horsepower and torque by forcing more air into the intake. The addition of extra air allows more fuel to be pumped in, and the resulting combustion returns more power than without the extra air and fuel. One problem that arises from this extra power is the creation of enormous amounts of heat and pressure inside a turbo-charged diesel engine. Monitoring these products and by-products of combustion are essential in the reliability of the engine's performance. Installing a boost gauge on a GM Duramax diesel engine is the first step in monitoring the engine during use, and is recommended for any turbo engine that has aftermarket parts installed or is driven for performance.
Park the GM Duramax truck in a work area that is flat and level with plenty of light. Open the hood and driver's side door to allow entry into the spaces that will house the new boost gauge and carry the lines to the engine that the gauge uses to operate. Disconnect the negative battery cable and tie away from the battery, disconnecting the truck from a power supply. Locate the fuse panel at the base of the driver's side A-pillar. An access panel covers the fuses at the very left of the dashboard. Remove the access panel by pulling it away from its fasteners. Keep the panel off to the side during installation.
Remove the center console on the roof of the passenger compartment. Use a screwdriver to locate and pry apart the fasteners that secure the console in place. These clips are all friction fasteners and can be separated by pulling and prying apart. Slowly work around the outer edge of the console until all the clips have come apart. The clips toward the back of the console are the hardest the get unclasped. These clamps need to be slid to one side or the other to release. Move the console in a position that you can use a screwdriver to help work the clasps apart. Before pulling the console away from the roof of the cab, check to see that you have unhooked the factory connections that are there. Utility lighting and accessory power are sent to the console using wires with releasable adapters. Release all these connections and then remove the console from the truck cab.
Place the center console on a flat surface or workbench. The console has a removable panel that is used for the installation of extra gauges like the boost gauge. Remove the panel and insert the boost gauge assembly in its place, or cut an opening in the panel with a coping saw to receive the new boost gauge. Connect the boost tube to the back of the gauge element, and connect the power supply wiring at this time as well. Making these connections to the gauge lets you complete the entire console installation prior to connecting the gauge to the engine and power supply. Once the gauge is installed in the console and both wiring and boost tube have been connected to the gauge, move the console back to the truck. Place the console face down, with the exposed back and gauge wiring available to feed through the console opening to the A-pillar.
Feed the wiring and boost tube in between the metal roof and the roof header inside the truck. Use a screwdriver to separate the headliner at the cabin's edge near the driver's side A-Pillar. Poke the metal wire coat hanger from the outside through to the hole in the headliner where the center console is attached. Tape the power supply wire for the gauge to the end of the coat hanger, and pull through to the outside. Repeat the process for the boost tubing. Once you have both wire and tubing ends out to the side using the hanger, install the center console back in place. Pull the tubing and the wire out more as you seat the center console back in place. Do not bend or kink the boost tubing while installing or laying the tube out during installation. Connect the snap fasteners of the center console starting from the back to the front, and the console installation will be completed.
Run the tubing and wire down the driver's side A-pillar. The bottom half of the A-pillar is removed by pulling away from its seated position. Held together with friction, these clamps will release under pressure, exposing the factory wiring that runs underneath. Run the power supply wire and the boost tube down the A-pillar. The power supply wire will end at the fuse panel at the base of the driver's A-pillar. The boost tube will need to be run through the firewall and into the engine compartment. Drill a ¼" hole in the firewall under the dashboard in front of the driver's seat. There is a place for the hole in an indentation in the firewall's sheet metal made at the factory. This is a good place to drill a new hole for the tubing to go. Protect the tube that sits in this newly drilled hole with some extra rubber hose around the boost tube that the hole will accommodate. Use silicon gel to fill in any opening around the boost tubing and the rubber hose that protects the tubing.
Use a fuse tap to connect the power supply wire to the fuse panel. Find a hot fuse when the ignition is turned on. A fuse tap that comes with the gauge is laid on the side of an existing fuse and, when the fuse is inserted into the fuse panel, it creates a protected circuit to the new gauge. Measure and cut the power supply wire. Connect the wire to the fuse panel using the fuse tap. Replace the fuse panel cover. Pull the boost tubing into the engine compartment so there is no extra tubing left behind, and replace the A-pillar cover.
The intake manifold has a tube connecting it to the turbo. Drill and tap a hole in this connecting tube for the other end of the boost tubing. The gauge should come with a sender that supplies this connection. When installed, the tubing will carry the boost pressure from this intake tube to the gauge for reading. Avoid letting metal shavings enter into the tube. It can be removed with a screwdriver and should be removed before drilling and tapping the hole to receive the tubing fittings. Secure the boost tubing to the firewall inside the engine compartment. Use existing wire conduit to house the new boost tube, and the installation will be complete. Connect the negative battery cable, shut the hood, and get in and drive your GM Duramax diesel engine truck or motor home.
- Use a magnet to collect the metal shaving if drilling the intake tube without removing it first. Drill slowly until the drill bit begins to break into the inside of the tubing. Drilling slow will produce curlicue metal shavings that a magnet can get to. Reach inside the tube after you drill with a magnet to pick up anything that may have fallen inside.
- Watch out for short circuits. Check your fuse before you install the fuse tap into your fuse panel. A simple test light will show you the fuse is operational after turning the key to accessory position. When the light is lit, the fuse is in use.