Engine Ticking Sound (Install Baffles into A.I.R. Hoses)

Some customers may comment about a "ticking" sound coming from the engine compartment while the vehicle is being driven. This noise may be described as similar to valve train noise or detonation, and most noticeable when the engine is completely warmed up (hot) and driven under load (2nd gear, 30-40 percent TPS, 1800-2500 RPM).

The noise may be due to an exhaust pressure wave that is migrating past the secondary A.I.R. check valves into the hose plumbing. The pressure wave produces an objectionable noise similar to valve train noise or detonation. The noise migration is due to system pressure imbalances and is not an indication of a component part malfunction such as faulty check valves.

1. Perform strategy-based diagnostics to determine the source of the engine noise. For evaluation purposes, disconnect the A.I.R. crossover tube (3) and cap off the check valve outlet nipples (1 and 6). If this is the condition responsible for the customer concern, the source of the noise has now been eliminated and can be confirmed with a test drive.
2. Procure three baffles, P/N 12562714.
3. Remove the A.I.R. hose and clamp (2) from the right side of check valve (1).



4. Insert one baffle (2) into the A.I.R. hose (3) using pliers and a twisting motion. The baffle (2) should be installed so that the near edge of the baffle is 35-50 mm (1.4-2.0 in) from the end of the hose.
5. Re-install A.I.R. hose (3) and clamp (4) to right side check valve (1).



6. Remove the A.I.R. hose (4) from the "T" fitting (5) located at the rear left side of the engine.
7. Install one baffle into the A.I.R. hose using pliers and a twisting motion. Make sure that the baffle is installed so that the near edge of the baffle is 35-50 mm (1.4-2.0 in) from the end of the hose.
8. Re-install rear A.I.R. hose (4) to the "T" fitting (5).
9. Remove the A.I.R. pump-to-"T" fitting hose (7) from the "T" fitting (5).
10. Install one baffle into the A.I.R. hose using pliers and a twisting motion. Make sure that the baffle is installed so that the near edge of the baffle is 35-50 mm (1.4-2.0 in) from the end of the hose.
11. Re-install A.I.R. pump-to-"T" fitting hose (7) to the "T" fitting (5).
12. Test drive vehicle to confirm that customer concern is repaired.
13. Return the vehicle to the customer.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: