Quick answer
3.5 EcoBoost Rattle on Cold Start: Cam Phasers or Timing Chain?
Published · 3 min read
Short answer: on a 2017-2020 F-150, Expedition or Navigator, a rattle for a few seconds after a cold start is most likely the cam phasers, and Ford has a bulletin (TSB 20-2315) and a software field action (21N08) for it. On a 2011-2016 truck, the usual suspect is the timing chain and its guides, covered by TSB 16-0027 and 17-0026. verified
Either way it is worth fixing soon: a phaser rattle sets cam-timing codes and can get worse, and a worn chain can shed guide material into the oil.
| Cause | Mostly on | What it sounds like | NHTSA complaints | Ford bulletins |
|---|---|---|---|---|
| Timing chain, guides and tensioner | Gen1, 2011-2016 | Slap or rattle that follows engine speed, can come back warm | 52 of 667 (peak years 2011: 14, 2012: 11, 2013: 10) | TSB 17-0026, TSB 16-0027 |
| Cam phasers (VCT units) | Gen2, 2017-2020 | Rattle for a few seconds right after a cold start, fades as oil pressure builds | 107 of 667 (peak years 2017: 17, 2018: 30, 2019: 25) | SSM 48055, TSB 20-2315, 21N08 |
From our EcoBoost failure maps: keyword matches in the 3.5 EcoBoost subset of NHTSA complaints on the F-150, Expedition and Transit, 2011-2026 (accessed 2026-10-20). Bulletins via NHTSA manufacturer communications. A count of reports, not a failure rate.
How to tell which one you have
Listen to when it happens. A phaser rattle lasts a few seconds at a cold start and fades as oil pressure builds. A chain slap tends to follow engine speed and can come back on a warm engine or at light load. aggregated
Read the codes. Both can set cam-timing codes (P0011, P0015 to P0019, P0021, P0025) or cam timing circuit codes (P0365, P0369). The codes say "timing", not which part.
Check the oil first. Low oil, old oil or the wrong filter make both worse. Our failure map lists oil level and filter as the first check before condemning the phasers.
Does Ford cover it?
Check the VIN at a Ford dealer for 21N08, a PCM reprogram for 2017-2020 F-150 and 2018-2020 Expedition and Navigator. TSB 20-2315 covers the rattle on 2017-2020 trucks built on or before 31 October 2019, and Ford's service messages say the engine computer needs a calibration update whenever the cam timing units or the engine are replaced. verified A bulletin is a repair procedure, not a free repair, so ask whether your truck is still covered by warranty or a program.
What it costs
Parts run from about $400 for a phaser and chain service to about $6,050 if the engine needs a long block, and shop labor is roughly 8 to 14 hours for the front-cover work. aggregated See our phaser and chain repair plan for the parts list.
FAQ
Is the 3.5 EcoBoost cold start rattle dangerous?
It does not usually stop the truck, but it is a sign of wear in the cam timing system. Left alone, phasers can set codes and run rough, and a worn chain can damage the engine. Have it diagnosed soon.
What years of 3.5 EcoBoost have cam phaser problems?
The complaints peak on 2017-2019 model years (17, 30 and 25 complaints). Ford's bulletins and the 21N08 action cover 2017-2020 F-150 and 2018-2020 Expedition and Navigator.
Is it the timing chain on a 2011-2014 EcoBoost?
On first-generation trucks the chain and guides are the more common story: chain complaints peak on 2011-2013 trucks, and TSB 17-0026 and 16-0027 cover 2011-2015 F-150s.
Go deeper
- Failure maps: Cam phaser and VCT rattle · Timing chain wear
- 3.5 EcoBoost platform page · EcoBoost recalls and programs · Noises, engine by engine
Sources. Ford service bulletins, service messages and field actions via NHTSA manufacturer communications, as listed on our EcoBoost failure maps. NHTSA owner complaints (US government public domain), keyword-matched. Parts prices at the time of publication; labor is a rough estimate. Torque Index takes no paid placement.