How to Find a Vacuum Leak

Updated: Apr. 30, 2022

Find a vacuum leak with this easy technique

how to find a vacuum leakFamily Handyman
Vacuum leaks can cause a variety of engine problems, and pros charge money to find them. Here's how to track them down yourself with a spray bottle.

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How to find a vacuum leak

Start the engine and spray

Scope out all the vacuum lines under the hood. Then start the engine and spray each connection with a light stream of water. If a connection sucks in the water, you’ve found your leak.

A vacuum leak can cause a rough idle, high rpm, poor gas mileage and even trigger a check-engine light. Pros find leaks by filling the engine with smoke and looking for wisps of it. But you can search for leaks on your own with an ordinary spray bottle using this technique. You might be able to solve the problem of a car not starting by looking into a vacuum leak.

Required Tools for this Project

Water spray bottle

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Water