How can I remove rusted exhaust manifold bolts?

Written by cameron easey
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How can I remove rusted exhaust manifold bolts?
The bolts on an exhaust manifold can rust. (New car petrol engines image by Christopher Dodge from

When you need to remove the exhaust manifold from your vehicle, the bolts that are used to secure it to the engine may be rusty. If that's the case, removing them can be somewhat challenging. You can remove rusted exhaust manifold bolts by heating the rusty nuts on the bolts with a torch and using penetrating oil.

Skill level:

Things you need

  • Propane torch
  • Penetrating oil
  • Socket wrench

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  1. 1

    Locate any rusty nuts that are threaded on bolts securing the exhaust manifold to the engine.

  2. 2

    Apply heat to the nut with a propane torch. Make multiple passes over the nut, but do not hold the torch in one place, because doing so could melt the metal. Continue to apply heat until the nut turns orange. When the nut expands from the heat, the rust that has bonded to the nut and the bolt will break away.

  3. 3

    Turn off the torch and apply penetrating oil to the nut and the bolt. Wait for the nut to cool.

  4. 4

    Repeat steps 2 and 3. Attempt to remove the nut from the bolt with the socket wrench. Apply more penetrating oil as the nut begins to turn.

  5. 5

    Continue turning the nut with the socket wrench until it comes off the bolt.

Tips and warnings

  • Heat only the nut, not the bolt on the exhaust manifold.
  • Applying too much heat can cause the bolt to break when you use the socket wrench.
  • Do not try to force a rusted bolt off with the socket wrench; this could crack the bolt.

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