On cold starts, basically anything below 60-F, there's a noise that sounds like a diesel engine idling.

2012 Boss 302 (Stock) with 23k miles...

It goes on for a while until (im guessing) the engine warms up to a specific temp. Once it hits that temperature, it stops, almost with a valve closing sort-of sound.

It does sound like its vibrating/rattling more as the RPMs rise too.

It's been at the dealer for a week now and they've been looking at all sorts of things (i'm told) without avail.
They're about to start looking into the engine.

I posted this in the Service/Warranty area but It may be better answered here...

Thanks for any help!
I'm pretty good with figuring out car problems, but this one has me and, i'm told the service techs, stumped.

It's going back into surgery sometime today hopefully, so hopefully i'll find out more.

UPDATE:
The dealer is telling me that they're thinking its a timing belt issue. They're waiting on a piece of equipment that will test the oil pressure in the engine. Then, they'll go from there.

However, I saw this posted on another thread by Gogoggansgo:

Could this be the issue?
Anyone with extensive knowledge would be an awesome help!

Thanks.

 

Forged pistons making a clattering noise when cold is well known to us old hot rodders. I have a '71 454 Chevy with forged pistons and it rattles the first couple of minutes when cold. Stops as soon as the engine gets some heat in it.

 

I Used to have an SVT Focus with the Forged Internals and it never made this noise...

So this is common and isn't an issue?

 

Well... this guy has hit the nail on the head.

I literately just got a call from Ford. My service adviser then proceeded to read to me a technical memo from Ford Engineering saying that, "on the 2012 Boss 302, the aluminum forged pistons will make a rapping/clattering noise against the cylinder wall on at cold temperatures.
It does NOT affect the durability and integrity of the motor and is completely normal."

Wow... Ironic how fast this reply and the official Ford reply came in together.
Thanks for your help!

 

If you take the injector insulators off the valve covers you can drown it out with valve clatter and injector noise.

 

... do people do this? lol

 

Not purposely, I did remove all of the foam crap and it makes the under hood noise much loader.

 

So revisiting this noise... I know Ford says it's normal... but I am curious still.
Whenever it stops, it doesn't simply slowly fade away. It's like it just turns off!
From loud to nothing!

Still sure it sounds like Forged Pistons?

 

You could take it in and see if it is caused by the water pump and have the TSB run on it.

 

Any more info on this? My car has the same problem. I left the car over night so the dealer could drive it from a cold start. Of course they heard nothing. Same goes for the transmission whine. I'm gonna have to bring it back again, and then come by there in the morning so I can ride with them.

 

Update... none. :/

The problem is, I just don't have time to take in and leave it... again.
The last time, they said its the forged piston cylinder slap. (it took them almost 2 weeks to get to that conclusion after checking oil pressure and all. The service adviser told me that each "department", (transmission, engine, electrical?, etc.) took a look and couldn't figure it out.

I'd love to take it to another dealer, but I need the car as a DD and no one has loaners. It's sort of making the warranty worthless since I can't leave it.

So right now, I just pray it doesn't rattle and embarrass me every day.

 

Does it sound at all like this?

 

Poster of that video should have reved that 5.0 up a couple of times. If that noise is the engine its an upper cam/timing noise.

 

Is it the Intake Manifold Runner Control(IMRC)?

I have a fusion and that stupid butterfly system makes a heck of a racket.

 

Glad I could help guys I work at the ford plant so I see all the warranty stuff but piston slap is normal and ask a lightning owner about that

 

it's normal my friend forged pistons contract over night and they have to expanded this makes a terrible noise nothing u can do

 

Our motors don't use charge motion plates the 15 5.0s have them

 

please DO NOT COMPLAIN about the noise from the forged pistons or there will be NO MORE HIPO Ford Mustang motors capable of OVER 780 REAR WHEEL HORSEPOWER with a blower or OVER 8250 RPM+witha tune and making 440 RWHP!!!!! The very reason we dont have more of these engines is because people complain about the noise they make. If the salespeople would tell customers its normal then we all would be set!!!!!!

 

I am sorry but you need to find another dealer ASAP! If they couldnt tell you that irs normal forged piston slap when cold then they are idiots! This is the VERY reason more manufacturers wont install forged pistons...lack of customer education as to their noise vs performance side effects! ugh this frustrates me because we would have more capable motors if people were educated. Besides if you know anything about this Roadrunner engine before purchase then you would know it has forged pistons...and if you don't know what they are then you shouldn't buy the car

 

My plant manger told my team the same thing