How to Remove Rust Inside Engines

Written by keith ruckus
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How to Remove Rust Inside Engines
Removing rust from engines will ensure better lubrication and usage. (old diesel engine image by Wd Photo from

Allowing rust to build inside engines will adversely affect the engine's ability to run properly. Rust build-up creates friction in the engine in places that are lubricated, causing excessive heat and often breakage. Rust also eats away at metallic surfaces and can create breaks in pipes, hose housings and belt bearings, making the vehicle inoperable. Using wire brushes, rust stabilisers and at times phosphoric acid will eliminate rust, allowing the engine to run more efficiently and safely.

Skill level:

Things you need

  • Thin bristled auto wire brush
  • Rust stabiliser (1 or 2 bottles, depending on amount of rust)
  • Phosphoric acid (2-liter bottle)
  • Bucket
  • Water
  • Empty spray bottle
  • Clean dry rags

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  1. 1

    Use the wire brush to scrape at rust deposits around the engine. Rub the bristle side vigorously up and down over battery contacts, smooth flat areas of the engine, pipes and sockets. Scrape the sides of the engine chassis, the underside of the hood and the engine mounts. Avoid contact with belts, hoses and other non-metal pieces.

  2. 2

    Apply a liberal amount of rust stabiliser to a clean dry rag (if the rust stabiliser purchased is in squirt bottle form, apply without a rag). Use the rag to apply the rust stabiliser to all the engine parts, even if there is no rust build-up. Keep applying until the engine has a light coat of the stabiliser and let sit as long as two hours to allow the stabiliser to break down the rust and protect the other areas.

  3. 3

    Dump the bottle of phosphoric acid into the bucket and add an equal part of water. Pour the solution of acid and water into the spray bottle (without touching it) and close the spray bottle firmly to avoid spillage. Spray a very light coating (no more than two pumps) of the solution over the rust-affected areas, avoiding non-rusted areas as much as possible to destroy the rust.

Tips and warnings

  • Phosphoric acid is a dangerous substance; use extreme caution when handling. Never allow skin to come into contact with any type of acid. Seek out medical assistance immediately for any problems with the acidic compound.

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