How to Find a Vacuum Leak With Propane

Written By
Chris Miksen
Chris Miksen
Published: Nov 21, 2011
Updated: Nov 20, 2021
2 minute read

By allowing propane gas to escape the tip of a propane torch, you can check for leaks along the intake manifold and listen for changes in your engine’s idling. A change in the idling means you’ve found a leak.

  1. Turn on your engine and lift the hood of your vehicle. Locate the intake manifold. The location of the manifold varies, but it's easy to spot. It's a single metal component that looks like a series of straight or spiral metal tubes. Hoses are connected to this manifold.

  2. Open the valve of a propane torch. Do not ignite it; just open it so that a bit of propane gas can escape the tip.

  3. Run the tip of the propane torch along your intake manifold, checking for vacuum leaks in various locations such as the tubes and gaskets. Go along the entire manifold.

  4. Listen for a change in your engine’s idling. The idling should change immediately after you pass over a leak with the tip of the propane torch. The reason the idling changes is because the engine will suck in the propane through the leak, providing the engine with more fuel.

The Drip Cap

  • Abnormal idling of your car's engine may indicate a vacuum leak in the engine's intake manifold.
  • By allowing propane gas to escape the tip of a propane torch, you can check for leaks along the intake manifold and listen for changes in your engine’s idling.
  • Locate the intake manifold.
  • Go along the entire manifold.
Chris Miksen

Located in Pittsburgh, Chris Miksen has been writing instructional articles on a wide range of topics for online publications since 2007. He currently owns and operates a vending business. Miksen has written a variety of technical and…

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