PDF download Download Article PDF download Download Article

Both gas and diesel combustion engines have manifolds. There are intake and exhaust manifolds in cars, trucks, motorcycles, and boat engines. Air and fuel mixtures enter the engine through the intake manifold, and fuel emissions exit through the exhaust manifold. The intake manifold and how it functions contributes to the engine's fuel efficiency. The exhaust manifold's job is to collect exhaust from the different engine cylinders and direct them out of the engine. The exhaust manifold is basically a pipe that leads to a catalytic converter and, then, through the muffler to the exhaust pipe. Of course, over time the manifold will collect dirt, dust, and corrosion. As this happens, the exhaust manifold loses efficiency in its job of releasing the gases, and it begins to foul the atmosphere, contributing to smog and endangering the driver and passengers. Even if you don't race your engines for sport or hobby, it is helpful to know how to clean exhaust manifolds on your own vehicles.

Get Car Support Solve Any Problem

wH
Hi there! Do you have a question about how to diagnose or fix a problem with your car? I’ve read the manual so you don’t have to. Select your make, model, and year, then ask away!
*
*
Method 1
Method 1 of 5:

Find the Manifold

PDF download Download Article
    • 4-cylinder engines have one exhaust manifold.
    • 6 or 8-cylinder vehicles have two manifolds.
    • Look for the manifold in front of the engine block on a front-end driven vehicle.
    • Find the manifold on the side of the engine block on a rear-driven.
    • This may vary slightly on boat engines or those on other small vehicles.
  1. [1]
    • Most exhaust manifolds are made of cast iron or a steel alloy similarly able to handle high temperatures.
    • Each manifold has an exhaust port matched to each exhaust outlet on the cylinder head.
    • The exhaust flows through these ports to a single outlet.
    • These ports are openings in an otherwise flat machined surface that fits with a gasket to the surface of the cylinder head.
    • Gaskets, made of paper, asbestos materials, or copper, serve as seals to prevent leakage between the manifold and cylinder head.
  2. Advertisement
Method 2
Method 2 of 5:

Work Safely

PDF download Download Article
  1. Advertisement
Method 3
Method 3 of 5:

Remove the exhaust manifold.

PDF download Download Article
  1. [2]
  2. Spray the bolts on the manifold heat shield (usually found on recent cars) with lubricating solvent and remove with socket wrench.
  3. Advertisement
Method 4
Method 4 of 5:

Clean the Exhaust Manifold

PDF download Download Article
  1. [3]
    • Lacquer thinner is a solvent, but it also cures the metal with a coating that you can thicken with repeated applications.
  2. Advertisement
Method 5
Method 5 of 5:

Remount the Manifold

PDF download Download Article
  1. [4]
  2. Contact your local dealer or research repairs in order to determine the precise sequence and torque level to follow when reinstalling the manifold.
  3. Advertisement


Community Q&A

Search
Add New Question
  • Question
    How do I stop carbon from going in the engine?
    Community Answer
    The only way is to not start the engine. Carbon comes from burning fuel. You can reduce carbon by making sure the thermostat is good (a hot engine makes less carbon) and by making sure your spark plugs, air cleaner and ignition system are in good condition, since fresh air and good sparks ensure a cleaner burn.
  • Question
    Can I jet wash the carbon deposit out of my exhaust without removing it?
    Community Answer
    No. The water and cleaner from the wash would end up inside the engine. Removing and jet washing is the only way.
  • Question
    Is it safe to drive if the exhaust manifold is blocked?
    Community Answer
    Exhaust flows from the head through the manifold/header. Theoretically it’s possible that the manifold could become blocked, preventing the engine from running, but that’s highly unlikely. Under normal conditions the carbon buildup that develops on the manifold is small and doesn’t significantly affect performance. If there was significant buildup to kill the engine, you would notice significant power losses prior to failure.
Ask a Question
      Advertisement

      Tips

      • Consider taking manifolds to a paint stripping business where they will chemically strip the metal.
      • Bolts that hold manifolds in place are sometimes difficult to turn, but using a power wrench is not advised.
      Submit a Tip
      All tip submissions are carefully reviewed before being published
      Name
      Please provide your name and last initial
      Thanks for submitting a tip for review!
      Advertisement

      Warnings

      • Do not use water or a water-based product to clean wrought iron, as the iron will absorb water and ruin the manifold.
      • Lacquer thinner emits toxic fumes, so be careful to work in area with good air circulation.
      Advertisement

      Things You'll Need

      • Safety equipment, including work gloves, dust mask, and goggles
      • Rags
      • Degreaser
      • Socket wrench
      • Lacquer thinner
      • Hand-held electric grinder
      • Stiff wire brush

      About This Article

      Thanks to all authors for creating a page that has been read 126,375 times.

      Reader Success Stories

      • Pure Energy

        Jun 20, 2020

        "Just knowing that someone is kind enough to put together so much info in this corporation-clogged world is a lot! ..." more
      Share your story

      Did this article help you?

      Advertisement