Leak Testing
multimedia:A supplement to the article is available.
WARNING:
The normal operating temperature of the exhaust system is very high. Therefore, never work around or attempt to service any part of the exhaust system until it is cooled. Special care should be taken when working near the catalytic converter. The temperature of the converter rises to a high level after a short period of engine operation time.
- Raise and support vehicle.CAUTION:
The air pressure must not exceed 4 psi, otherwise engine damage can occur.
- Connect an Exhaust Cone to an adjustable air pressure regulator.
(special tool #8404-ECT, Exhaust Cone, Truck)
- Attach shop air to the air pressure regulator.
- Adjust the air pressure regulator to 4 psi.
- Insert an Exhaust Cone into the vehicle tail pipe.
(special tool #8404-ECT, Exhaust Cone, Truck)
- If the vehicle is equipped with dual exhaust, use an Exhaust Cone with equipped attached plug. Plug one side of the dual exhaust pipe. Pressurize the other as described.
(special tool #8404-ECT, Exhaust Cone, Truck)
- Apply a mixture of liquid dish soap and water to the following areas:
- All welded joints from 6 inches rearward of the downstream O2 sensor forward
- O2 sensor seal points
- O2 sensor boss welds
- Flange/joint connection(s)
- Catalytic converter to cylinder head connection(s)
- EGR valve and EGR tube seal points
- Observe the liquid/soapy water for bubbles.
- Use the following definitions to help determine if a system or component repair/replacement is necessary:
- Type 1 Leak is defined as a leak where very small foam like bubbles 1 mm (.039 in.) or less appear. Any Type 1 or greater leaks found in welded joints, O2 sensor seal points or O2 sensor boss welds must be repaired or the component must be replaced.
- Type 2 Leak is defined as a leak where larger bubbles 8 mm (.031 in.) or greater appear. Any Type 2 or greater leaks found in flange or joint connections, exhaust manifold to cylinder head connections, or EGR gasket and tube seal points must be repaired or the components must be replaced.
| Leak Location | Repair required if results at 4 psi reveal bubble size: |
|---|---|
| Welded joints | Type 1 - 1 mm (.039 in.) or greater |
| O2 Sensor seal points | Type 1 - 1 mm (.039 in.) or greater |
| O2 Sensor boss welds | Type 1 - 1 mm (.039 in.) or greater |
| Flange/joint connections | Type 2 - 8 mm (.031 in.) or greater |
| Catalytic converter to cylinder head connections | Type 2 - 8 mm (.031 in.) or greater |
| EGR gasket and tube seal points | Type 2 - 8 mm (.031 in.) or greater |
If a leak is found that matches the above definition, repair or replace the component as necessary.
Once the repair is complete, repeat the procedure to verify that all leaks have been repaired.