Comprehensive Engine Bay Detailing and Protection

Ensure the engine is 'touch warm' but not hot. A stone-cold engine makes grease harder to move, but a hot engine (over 50°C) will cause chemicals to flash-dry instantly, leading to permanent staining on aluminium and plastic. If the car was recently driven, leave the bonnet open for 30-45 minutes.

Use a vacuum or leaf blower to remove loose leaves, gum nuts, and insect remains from the cowl area and corners of the engine bay. These organic materials hold moisture and can cause rust or block drainage channels if washed deeper into the bay.

Identify the alternator, aftermarket air filters (exposed pods), fuse box, and any exposed spark plug wells. Wrap these tightly in aluminium foil or plastic wrap. Aluminium foil is superior as it holds its shape around awkward components without needing tape.

Mix your APC. For heavy red dust and grease, a 1:5 ratio (water to product) is standard. For lighter maintenance, 1:10 is sufficient. Using a foaming sprayer can help the product dwell longer on vertical surfaces without running off.

Start with the underside of the bonnet. If you have a fabric liner, avoid saturating it; light misting and a gentle wipe are enough. If it is painted metal, apply degreaser, agitate with a large brush, and rinse. Cleaning this first prevents dirt from dripping onto a cleaned engine later.

Before adding water, use a dry detailing brush to loosen red dust around the battery tray and strut towers. This prevents the dust from turning into 'mud' which can be harder to flush out of tight gaps.

Perform a very light rinse using a fan spray pattern. Keep the nozzle at least 30-50cm away from the engine. The goal is to dampen surfaces, not flood them. Avoid direct high-pressure spray onto electrical looms or sensor connections.

Apply your diluted degreaser liberally across the entire bay, starting from the bottom and working up. Focus heavily on the lower subframe and areas under the oil filter where spills are common. Let it dwell for 3-5 minutes, ensuring it does not dry.

Use your brushes to work the degreaser into all nooks. Use a long-reach brush for the front of the engine block and a soft boar's hair brush for the top plastic covers. Agitation is the key to breaking the static bond of Australian road film.

Rinse thoroughly from the top down. Use a systematic approach to ensure all chemical residue is flushed away. Watch for 'white' runoff—this indicates remaining degreaser. Continue rinsing until the water runs clear.

Check for missed spots, particularly behind the intake manifold or near the firewall. If grease remains, spot-clean those areas specifically rather than re-washing the whole bay.

This is the most critical step. Use compressed air or a high-powered blower to push water out of spark plug wells, electrical connectors, and bolt heads. Standing water in these areas leads to corrosion and 'check engine' lights.

Wipe down all accessible surfaces with a microfibre towel to prevent water spotting. In high-mineral water areas (common in regional Australia), water spots can etch into plastic and metal very quickly.

Carefully remove all foil and plastic wrap. Check that the areas underneath are dry. If any water seeped in, dry it immediately with a clean towel.

Apply a water-based dressing to all plastic and rubber components. Mist it onto a microfibre applicator and wipe it on. This provides a UV barrier and makes future cleaning easier as dust won't stick as readily to the protected surface.

Start the engine and let it idle for 5-10 minutes with the bonnet closed. The ambient heat generated will evaporate any remaining moisture in hard-to-reach areas. Keep an eye on the dashboard for any warning lights.