How to find a vacuum leak and how to fix it (8 easy steps)

You should inspect your vacuum hoses before proceeding to the next step in this guide. Vacuum hoses are made of rubber material, which will become hard and start to crack after some years in the engine’s heat. You should replace any defective vacuum hoses that you find.

If you couldn’t find any cracked or leaky vacuum hoses or other parts in the engine bay, it is now time to fire up the engine. Turn on the parking brake and put the gearbox in Neutral/Park. The engine will now be started. During this guide, be careful not to touch hot or moving parts.

For this next guide you will need to have a flammable fluid available in either spray form or as a gas. Starter spray, brake cleaner and carburetor cleaner are all options. Propane gas can also be used from a propane torch to make it work. These steps should be performed with a carburetor or propane torch.

Spray the spray, then locate the location where the intake manifold connects to the cylinder heads. Then spray the connections on the individual cylinders. If the car’s RPM changes or starts to sound weird, your car most likely has a bad intake manifold gasket. You can also try to spray around other suspected areas on the intake manifold if it’s divided into several parts.

Spray around all connections. They may leak even though they appear to be in good condition. Also, you can follow the hoses to spray the opposite end. Vacuum leaks are easy to spot if your engine's RPM is higher than normal.

Brake boosters create a vacuum that allows you to brake without pressing too hard. To locate leakages, spray around the connector and around other parts of the brake booster. You have to be very carefully listening to the engine’s RPM here, though, because t is so far away from the engine, so it is not sure that it will be noticeable.

To find actuators and solenoids connected to vacuum systems, look around the intake manifold. Plastic actuators and solenoids can become cracked over time. Spray them, especially if the axles are attached to your intake manifold. Leakage can be corrected by replacing faulty solenoids or actuators.

We have just one more thing to look at. It is the gasket that connects the throttle body to the intake manifold. You can bolt your throttle body to the intake manifold using 3-4 screws. Sometimes there's a rubber, paper or plastic gasket that seals these two pieces together. Sometimes, the gasket may become brittle and begin to leak. To check for any leaks, spray around the throttle body.