Rattle upon start up

[Avega96]

Hi, I recently purchased a 2017 Shelby GT350 with 38,000 miles. Shortly after, I noticed a rattling noise that only occurs when starting the car back up after it has been sitting for 20+ minutes never on cold starts.

I took it to Ford, where I was able to replicate the noise for a technician. He initially diagnosed it as an issue with the cam phasers. Since I don’t have a warranty, I asked for a cost estimate, and he said he would get back to me.

A week later, I followed up with the service rep for an update. He told me:
“We did get an answer back from engineering, but nothing too helpful or conclusive. At this time, we don’t have much to go on. Even the possibility of the cam phaser issue isn’t definitive. We want to avoid tearing down the engine without a clear direction, especially since this would be an out-of-pocket expense. For now, our recommendation is to hold off until the symptoms give us a clearer idea of what’s going on.”

Any ideas on what could be causing this?

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[NPTR]

I have a Ranger Raptor with an Eco Boost V6 and they have been plagued with cam phaser issues - on cold start, it produces a sound just like that if you have faulty ones. On the eco boost it sounds worse / lasts longer, but it’s a very similar sound…haven’t heard of the voodoo having a similar issue, but sure does sound like that…worth poking around those videos and seeing how similar it is.

 

[Avega96]

hey, thanks for the reply. Yeah I’ve done a bunch of research on what it could possibly be and it sounds like the typical cam phaser rattle that the EcoBoost makes when they go bad. Except mine only makes it when the cars been warmed up, cooled down for a bit then started back up. The service rep at the dealership pretty much told me to keep driving it until it gets worse. I just can’t stand that rattle noise plus my mpg seems to be slowly decreasing along with feeling sluggish at times

 

[P85596]

I just had a similar noise, it only happened on cold start up and went away within a minute or so. The problem turned out to be a stuck butterfly in the intake manifold.

 

[icecreamtruckz]

Mine doesn’t do that. That would scare me too. Could be nothing major. If it never gets worse it never gets worse.
I do have piston slap when cold 3k rpm’s and it’s loud, at least to me.

So this doesn’t happen on cold starts? Just warm ones? And you never hear it just driving around?

 

[Avega96]

Yeah, the rattle only lasts for a second or two before disappearing. It never happens while driving or on a cold start only after the car has been driven, turned off, and restarted after sitting for about 20 minutes. I took it to a local mechanic, who thought it might be the timing chain, but I don’t think that’s the issue. Then I brought it to Ford, and right away they said it sounded like the driver-side cam phaser until I told them that it was out of warranty

 

[Joe Gonsalves]

2 things, the cam phasers run on oil pressure controlled by the VVT solenoids. The VVT solenoids get clogged with very fine particles. There is a procedure to clear them out by applying 12V to the connector pins a few dozen times. There is a TSB on it but I don't recall the number. They are easier to change out than the phasers. The other thing is oil, is it low or the wrong viscosity. Personally I think 5W20 is to low. Not saying for you to change it to 10W30 but I think it would help when oil temp is hot and it can't hold the pressure in the cam phasers. Changing the cam phasers out requires a service tool to lock the camshafts in position. Then it's straight forward, but not a DIY task.

 

[robvas]

Have seen that on the Pentastar 3.6 and Ford 5.4, only at cold startup. It's the phasers on the Dodge/Jeep and something different on the old Ford 5.4. Wonder if it's the same issue on the Coyote?

 

[Avega96]

I’ve been using the 5w50 oil that is recommended for the voodoo engine. if I remember correctly the technician at ford said it was going to cost around 5-6k to fix, mainly paying for labor. I’m definitely going to look into clearing the VVT solenoids like you said when I get back from the Philippines. I’ve been mentally preparing to do the whole timing overhaul job myself since I can’t justify paying that much just for labor when that money can go towards other parts

 

[barstowpo]

I have this issue when starting a hot engine. There are several threads about it. I simply hold the throttle wise open for a couple of seconds when cranking and th noise is eliminated. Also blipping the throttle at out off hips too.

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