Ford Bronco 2.7 startup rattle/knock

[PWMDMD]

My business partner has a 2025 Bronco with the 2.7, just 33k miles, and it is meticulously maintained at the dealership. We were leaving work yesterday and he asked me to listen to him start the engine where there was 4 or 5 seconds of knocking (he called it rattling but you could hear individual hits of metal on metal) that then went away. He turned the car off and turned it back on and it sounded normal. I was thinking chain tensioner but this is not my wheel house. This started about a week ago and it happens 100% of the time after it sits and the engine gets cold. No dash lights and otherwise drives normally. Wondering what you all think?

He only has 33k miles on it's been to the dealership for a bunch of issues. The last being an intermittent issue where all the dash board lights light up and the safety systems and AWD/traction control/etc are unavailable. Eventually, the dash lights went off and the systems came back online. Ford had it for about a week and stated no stored codes and they couldn't reproduce the issue. Told him to come back with the dash lights on even though they've gone off on their own every time so far. He picked it up and it happened on the way home but they were then closed. The next day the lights were off. Not ready to call it a lemon but it's been in for a number of other issues and Ford doesn't seem to know how to fix the electrical issue.

 

[Trav]

It could be something in the timing chain system or a valve lash adjuster (commonly known as a lifter). Time to go back to the dealer.

 

[MalibuRam65]

Ford can’t be still having Timing,VVTI rattle issues they can’t smh.

 

[SC Maintenance]

When was the last oil change? Could be the ADBV on the filter not working given its only on cold start? Cheap thing to try - changing the filter only and see if it persists?

 

[2.7ecoboostFordBronco]

Seems to be a classic Cam Phaser locking pin failure. Can you provide us with video of a cold start? I would also get video evidence and take it to a different dealer. You want this fixed before powertrain warranty expires, as it is easily north of $5k approaching $10k to fix. Eventually it can lead to engine failure if uncorrected although it takes a long time.

Does it sound like this? This is the cam phaser issue:


Maintenance doesn’t really play a role in all of these failures as I’ve heard of it happening in less than 5,000 miles since new, although it can play a role with enough neglect over time. The parts are simply defective in many cases.

The other possibility is a turbo waste gate rattle which is common but doesn’t really fit what you describe.

 

[ka9mnx]

Could also be piston slap. I had that issue in the cold on my F150 when I tried 5w-20 oil. Ford said, in a TSB, that it's what they now recommended. Stupid me. Went away when I went back to 10w-30 which what Ford originally recommended.

 

[xspeedy]

I thought these cam phaser issues were limited to the 3.5. But yeah, as mentioned it sounds like that. You can find many videos if you search “F-150 cam phaser rattle”.

 

[2.7ecoboostFordBronco]

I thought these cam phaser issues were limited to the 3.5. But yeah, as mentioned it sounds like that. You can find many videos if you search “F-150 cam phaser rattle”.

The 2.7 does occasionally have the problem. I would say that it is uncommon, probably around 1% of the 2.7 powered Broncos get the cam phaser rattle problem early in life, before 30k miles. I’m just wildly guessing since Ford would never tell us the number. I hear about it occasionally in the online Bronco groups. The 2.3 engined Bronco seems a lot less susceptible (haven’t heard of that engine with this problem). I don’t think it’s oil or maintenance related when they prematurely fail like this, just parts/manufacturing defects, which is sad. It can also start to happen to these 2.7 (and 3.5) engines as a result of wear around 200k miles from talking to the F-150 guys.

 

[meep]

I had a 2.7 in a 2018. It was a wonderful motor. Around 70k I noticed that startups were getting noisy. It was normally very quiet. By 80k it was making a lot of noise for about 20 seconds, and I started finding tiny shiny bits in the oil filter. Definitely sounded like chain noise.

Between that looming repair, the finicky transmission and a failing hvac blend door motor (#2), we were done. Those 3 repairs came close to trade in value of the truck.

 

[PWMDMD]

He brought it to Ford and a cam phaser needs to be replaced. Still no resolution on his intermittent electrical issues.

 

[Gawardawg]

I had a 2019 F150 with the 3.8 n/an engine. They recently dropped it. That was a really good base truck engine. I loved it. It was a really good truck. I had it for 6 years and traded it on a 2025 Nissan Frontier with the VQ38DD. We’ll see. But I got rid of my ford due to warranty going out and the current cam phaser issue with all of them with this set up. The issue is with a pin that locks into a hole. Hole wears out or pin shears. It works great till then. There is a kit that some use to lock the phaser in place so it don’t jump around and make all that noise. The noise itself is worse than what’s actually happening. But there’s only one way to correct it. Replace it. $$$$&. Might as well go through the timing chain while you’re there. $$$$&$.

 

[Gawardawg]

There are really good videos that show how the cam phaser works and what’s happening when it’s knocking.

 

[oil pan 4]

Death rattle 2

 

[Kurtatron]

Sorry to hear about all that’s going on for your coworker. This is why I prefer older cars of yore with less stuff on them. My 2005 Ford Focus has been rock solid dependable as a daily driver. I wish automakers could make a cheap, basic vehicle again.