Professional Engine Bay Detailing and Degreasing

The engine must be cool to the touch or only slightly warm. In Australian summer, never clean an engine that has been running for hours. If the block is too hot, cleaning chemicals will flash-dry instantly, causing permanent staining on metal and plastic. Aim for an engine temperature of roughly 30-35°C—lukewarm, not hot.

Identify and cover sensitive areas. Use cling wrap or foil to tightly wrap the alternator, the air intake opening, the fuse box, and any exposed aftermarket wiring (like spotlights or dual battery solenoids). This prevents water ingress which can cause short circuits or 'Check Engine' lights.

Before adding moisture, use a vacuum or a leaf blower to remove loose leaves, twigs, and dead insects from the cowl area and corners. This prevents these organic materials from turning into a muddy sludge that clogs drainage channels during the washing process.

Mix your APC in a spray bottle. For a standard engine bay, a 1:5 ratio (one part chemical to five parts water) is usually sufficient. If you have heavy red dust from a recent Outback trip, consider a slightly stronger 1:3 mix to penetrate the silicate bonds of the dust.

Using a gentle fan spray from your hose or pressure washer, lightly mist the entire engine bay. Start from the underside of the bonnet and work down. The goal is to dampen the surfaces, not to flood them. Keep the nozzle at least 50cm away from the engine components at all times.

Apply your degreaser to the underside of the bonnet. Focus on the edges where grease accumulates. If you have a fabric heat liner, avoid soaking it; instead, lightly mist and blot with a microfibre towel. For painted sections, agitate with a soft brush and rinse immediately.

Spray your diluted APC liberally across the engine bay, starting from the back and moving forward. Focus on the heaviest areas of grease, typically around the valve cover and lower engine block. Allow the product to dwell for 3-5 minutes, ensuring it does not dry out in the heat.

This is the most important step. Use your detailing brushes to work the cleaner into every nook and cranny. Agitate the plastic engine cover, fluid reservoirs, and cooling hoses. The physical action of the brush breaks the bond between the grime and the surface, which chemical action alone cannot always do.

The front area near the grille often collects the most bugs and salt. Use a soft brush to clean the plastic shroud and the top of the radiator. Be extremely careful not to bend the delicate aluminium fins of the radiator if you are cleaning near them.

Rinse the engine bay thoroughly using a low-pressure setting. Work systematically from top to bottom. Ensure all white soapy residue is gone. Pay close attention to recessed areas where soap might pool, as leftover degreaser can etch plastic over time if left to bake in the sun.

Inspect the bay for any remaining grease or red dust. Often, heavy deposits require a second pass. Repeat the degreasing and agitation steps only on the missed spots. This targeted approach minimises the amount of water introduced to the engine.

Use a leaf blower or compressed air to blow water out of every crevice. Focus specifically on spark plug wells, electrical connectors, and bolt heads. Removing standing water is critical to prevent corrosion and ensure that your dressing will bond correctly in the next steps.

Use your dedicated workhorse microfibre towels to wipe down all accessible surfaces. This removes any remaining water spots and picks up the last remnants of dirt that the rinse might have missed. Ensure the bay is completely bone-dry before proceeding.

Carefully remove the cling wrap or foil from your alternator, intake, and fuse box. Use a slightly damp microfibre towel (with a tiny bit of APC) to hand-clean these items. Never spray water directly onto these parts even after they are uncovered.

Apply a water-based dressing to all plastic and rubber components. You can spray it directly onto a microfibre applicator and wipe the surfaces. This provides a UV barrier against the Australian sun and makes future cleaning much easier as dust will not stick as readily.

After letting the dressing sit for 5-10 minutes, use a clean microfibre towel to buff off any excess. This leaves a natural, factory-satin finish rather than a greasy, high-gloss look that attracts dust. Your engine bay should now look clean, dark, and uniform.

Start the engine and let it idle for 5-10 minutes. The heat generated by the engine will help evaporate any remaining moisture in hard-to-reach areas. Keep an eye on the dashboard for any warning lights, though if you followed the waterproofing steps, there should be none.