Front end rattle at low acceleration
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2020 F-150 5.0: Front end rattle at low acceleration, not IWE?
Going through the classic F-150 rattle, reading through previous threads leads me to IWE system, troubleshooting so far below. Truck is a 2020 F-150 5.0. The worst is 35-40mph, coasting and then a light pedal will make a head turning rattle or at low speed on a cold engine. Seems to be more frequent recently but maybe I'm just really listening for it. Just got done with the following and it's still there after my test drive:
Crawled around pulling on heat shields just in case, can't find anything loose as described in other threads.
Replaced check valve and solenoid.
Confirmed vacuum with pump/gauge on both sides of check valve.
Confirmed good DC to solenoid / fuses.
Pulled vacuum on the vacuum line out of solenoid to the actuators. Holds 20inHg for 2+ minutes.
Pulled vacuum on left and right actuators at the hubs. Holds 20inHg for 2+ minutes.
Put the tires back on, pulled 20inHg at the hubs individually and at the vacuum out of the solenoid. 20inHg allows the wheels to spin free (2wd), removing the vacuum engages the drive (4wd).
Seems to function as it should? Only thing I find odd is that the solenoid does not show a vacuum on startup (shouldn't for the first 0.5 mile?)
Solenoid will show 20inHg of vacuum on shut down for about 10 seconds then back to zero.
Only other thing I found was a rock in brake rotor shield but doesn't look like it was there for long. No scratches. Test drive, rattle is there 2wd and 4wd. Thinking about jumping the check valve to the solenoid out to see if there's a change. Might not be the IWE system at all. Is there a chance my reservoir is bad?
Any tips much appreciated
Crawled around pulling on heat shields just in case, can't find anything loose as described in other threads.
Replaced check valve and solenoid.
Confirmed vacuum with pump/gauge on both sides of check valve.
Confirmed good DC to solenoid / fuses.
Pulled vacuum on the vacuum line out of solenoid to the actuators. Holds 20inHg for 2+ minutes.
Pulled vacuum on left and right actuators at the hubs. Holds 20inHg for 2+ minutes.
Put the tires back on, pulled 20inHg at the hubs individually and at the vacuum out of the solenoid. 20inHg allows the wheels to spin free (2wd), removing the vacuum engages the drive (4wd).
Seems to function as it should? Only thing I find odd is that the solenoid does not show a vacuum on startup (shouldn't for the first 0.5 mile?)
Solenoid will show 20inHg of vacuum on shut down for about 10 seconds then back to zero.
Only other thing I found was a rock in brake rotor shield but doesn't look like it was there for long. No scratches. Test drive, rattle is there 2wd and 4wd. Thinking about jumping the check valve to the solenoid out to see if there's a change. Might not be the IWE system at all. Is there a chance my reservoir is bad?
Any tips much appreciated
Last edited by okie20202; Oct 7, 2025 at 02:16 PM. Reason: Title Change