Ford: Ticking/Knocking Noise Or Rattle From Engine On Startup – UnderhoodService

Ford: Ticking/Knocking Noise Or Rattle From Engine On Startup

Some vehicles equipped with a 4.6L, 3-valve or 5.4L, 3-valve engine may exhibit a ticking and/or knocking noise after reaching normal operating temperature, or may exhibit a rattle upon starting. The noise may also be described as ticks, taps, knocks or thumps. In some cases the noise may be a normal characteristic of these engines. In other cases the noise may require further investigation. Sorting out and defining the noise as reported by the customer is important to diagnose and repair the condition.
2005 Mustang
2004 F-150
2005 F-150, F-250, F-350
2005 Expedition
2005 Lincoln Navigator
Note: The 4.6L, 3-valve and the 5.4L, 3-valve engines are installed in several vehicle platforms, which may influence the intensity of noise due to vehicle differences in sound transmission paths, hood and body insulation packages and root cause of the component(s) causing the noise.
1. Make sure you have a detailed description of the noise the customer is concerned with, including details such as:
• Is the noise occurring at idle or above idle speed?
• Does it disappear above 1,200 RPM?
• Does the noise occur when the engine is hot? Cold? Both?
These engines generate a lot of “normal” noises, so it is critical to confirm the noise the customer is concerned with and the environment the customer is in when the noise is noticeable to them. Validate by using your own perception.
2. Compare the noise generated with a new vehicle, if available, with an engine build date of March 30, 2005, or later for the Mustang and April 18, 2005, or later for the F-150, F-250, F-350, Expedition and Navigator.
3. Diagnose the noise when the engine is at normal operating temperature (oil at 160º F or above). Verify the oil temperature with a diagnostic scan tool and monitor the engine oil temperature (EOT) PID. Startup rattle may only occur with cold oil.
4. Check the type of oil filter installed on the vehicle. A dirty or clogged filter may cause a pressure drop. Look for aftermarket brands not recognized in the market or a production filter that has gone beyond the standard Ford-recommended change interval.
5. Check for signs of oil brand used and viscosity.
Once the above pre-checks are complete, check for sound level from the following components in the order listed. Compare the sound from these components to the noise the customer is concerned with to determine the source.
Injection/Fuel System
Injector noise (ticking) is considered normal. Noise increases with RPM, hot or cold, and is recognized at the top of the engine.
Valve Train
Lash adjusters can make a ticking or tapping noise noticeable at any engine RPM or temperature. The noise is audible through the wheel well or an open hood. However, with the hood down, the lash adjuster noise can be heard as a light tapping noise through the wheel well and is considered normal.
Tracing this noise requires isolating it to a cylinder bank. If one bank is louder than the other bank, focus the diagnosis on the loud bank. If both banks seem loud with the hood down, compare wheel well sound level to another comparable vehicle.
Use a stethoscope on the top of the cam cover bolt heads to confirm which bank is affected. Move the probe from front to rear if necessary.
If isolated, only replace the intake and exhaust lifters on the affected cylinder bank.
Variable Cam Timing
The 4.6L, 3-valve and 5.4L, 3-valve variable cam timing (VCT) feature may emit a light knock in normal operation and is audible only at idle speed with a hot engine (gear selector in park or neutral). However, it may be masked by or mistaken for other noises generated from either the injector firing or a malfunctioning valve train as described earlier.
The noise does not affect the performance or durability of the part.
VCT phasers may knock at hot idle. The knock may be heard inside the passenger compartment or the wheel well area. Some light noise is normal. The engine may require a cold soak overnight to effectively make a full diagnosis at hot idle, particularly when a VCT phaser is suspected. The knock is not prevalent at cold temperatures.
To Test For VCT Noise
1. Place the transmission in park or neutral
2. Bring engine oil temperature to 160º F or above as indicated by the scan tool EOT PID.
3. Allow engine to idle and determine if noise is noticeable.
4. Set engine speed to over 1,200 RPM. If the noise is a VCT knock, it should disappear.
5. Return the engine speed to idle and verify if the knock returns.
If the noise intensity is more than a lightly audible knock at hot idle than under 1,200 RPM at engine operating temperature, replace the cam phaser using the “In-Vehicle Repair Camshaft Phaser and Sprocket” procedure found in the Workshop Manual, section 303-01.
Startup Rattle
Some 2004 F-150 and 2005 F-150, Expedition, Navigator, F-Super Duty and Mustang vehicles may have a rattle on startup that lasts 1 to 3 seconds. If initial pre-checks have been completed and the noise sounds like it is coming from the front engine, replace the VCT Phaser Kit. If the engine continues to make the rattle noise after initial startup, do not exchange the VCT.
Courtesy of Identifix.

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