Acura RDX (2G) Engine Block Heater Installation

Work on a fully cold engine. Before draining any coolant, verify that the tools on hand can physically reach the block heater screw plug, because the bore sits in a very tight pocket of the engine bay. Peer through the long slot at the hood latch/lock with a flashlight, or drop a small camera into the space between the radiator and the engine, to spot the plug beside the block casting that carries the engine type and serial number. Only proceed to drain the system once you are confident of access.

Take out the air duct over the engine to open up the working area. Approach the plug from a roughly 45-degree side angle rather than straight down, since the valve cover and ignition coil packs block a vertical path to the bore.

Locate the white plastic radiator drain valve above the access hole in the plastic under-body pan. Turn it counter-clockwise, viewed from the end of the valve, to open it. Unlike some other makes, this drain is flush with the radiator and has no spigot, so feed the coolant through a small funnel into a clean container if you intend to reuse it. Access here is tight for larger hands.

The block's coolant drain sits toward the passenger side at the back of the engine. Using a 12 mm box-end wrench (or a deep socket), crack the bleeder screw loose, then cycle it open and closed with the wrench. Push a length of vinyl tube (about two and a half feet) firmly over the bleeder so the coolant runs into your clean container for reuse.

Release the front O2 sensor connector by pressing its tab and pulling it upward, then free the connector from its metal bracket by pressing the tab and pushing it downward. Undo the bracket bolt with a 14 mm socket. Raise the automatic transmission fluid dipstick about five millimeters and swing it toward the radiator so it is out of the path. Shift the bracket and its wiring toward the battery, tucking it against the radiator hose and tying it back if needed. This clears room for a socket on the heater plug.

With the bracket cleared, seat a 19 mm deep socket on a 1/2 inch square drive with a long flex or breaker handle onto the plug and break it loose; it then backs out by hand. Withdraw the plug together with its aluminum sealing washer. Be ready with a container: roughly a liter of additional coolant pours out of the heater bore even after the radiator and block have been drained.

Inspect and clean the threads in the engine block bore and on the block heater element before fitting. Clean, dry threads are needed for the sealant to work and for an accurate torque reading.

Fit the aluminum sealing washer to the element; do not leave it off. Coat the element threads with a thin layer of Permatex Form-A-Gasket No. 2 sealant (part No. 2BR, UPS 80500), a non-hardening compound specified for this Honda/Acura heater kit. Start the element by hand into the block bore. The hex on the end of the element takes a 24 mm socket.

Tighten the heater element with the 24 mm socket to the specified torque of 75 - 85 Nm (55 - 63 lbf.ft.).

Confirm every coolant drain is closed and reinstall the O2 sensor bracket, connector, dipstick, and air duct. Refill with the reserved coolant, or fresh coolant if the old was degraded, and top up as required. Do the final top-up only once the engine is warm, the cooling fans have switched through several on/off cycles, and the thermostat has opened; keep the reservoir between MIN and MAX until the level stops dropping. Once the engine is back to ambient temperature, remove the radiator cap and confirm the coolant sits at the top of the filler neck. Inspect for leaks. Route the heater's power cord to suit your parking setup, with the engine cold.