Loud Rattle Noise From Under Hood When Cold.

This is my first post on StangNet.
Sorry if this is a repost.
Any ideas or help would be greatly appreciated.

The car is pictured in my avatar and is an '06 GT with 20k miles and still running the factory recommended 5/20 synthetic blend Motorcraft oil.

The problem is a loud rattle/clatter noise from under the hood under hard acceleration that begins at 4k rpm's only when the engine/coolant temp. is in the cold range. The noise does not happen after the engine/coolant temp has warmed into the warm/normal temp. range.

To me this noise sounds just like and old push rod V8 valve rattle.

I went to the dealership I bought it from and asked if they had any tech. bulletins on this or have had any other complains like this. They said "no not at all" and suggested the noise I was hearing was due to the car/oil not being warmed enough to allow for the valve train to be properly oiled and suggested I change my driving habits... I thought that this was TOTAL B.S.

Anyhow... I've done some reading on this problem on the Internet and have read it could everything from incorrect valve lash to a bad factory engine tune.

I'm going to take it to the dealership tomorrow mourning and let it cool down and then take the service writer for a test ride to show what I'm talking about.

Any ideas from anybody?

erzats said:

Just a question why would you have it in 4500 range before its warmed up . Mine only takes about 2-3 miles to warm up on the coldest days in nj . Try driving "granny like" till it warms up and see if will do it.

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AlloyGT said:

I'll be interested to hear what they say, once they hear the noise in person. Does it sound like gravel rattling in a can?

Not to offend, but your driving habits could stand a little tweaking, perhaps. I would let the motor get up to normal temp before accelerating hard, but that's just me.

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LOL... OK, yes I should let if warm up completely before gettin' on it. I always let it sit and warm up at idle for about 5 minutes before driving it. When I leave work or the house I just can't resist sometimes.

Here in the Dallas area it rarely gets below freezing.

I'll keep your suggestions in mind.

Yes, gravel rattling in a can would be an accurate description.

I did find a Tech. Bulletin about sticking valve lash adjusters with my engine build date... Thanks :SNSign:

AlloyGT said:

Detonation sounds like gravel rattling in a can. This is not a good thing. Are you running a tune, or is it stock? You might need to be putting premium in it.

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Good point...

I'm running the stock factory tune.

I used to always use premium fuel and never noticed the problem then.
Ever since gas prices went through the roof I switched to the regular (cheaper) stuff.
I never switched back. Now that gas is cheap again I should probably go back to the good stuff.

I asked the dealership the same question and they said that wouldn't be the problem. But I am starting to think the service writers up there either don't care or don't know a damn thing.

Update here...

I finally found the time to take it into the dealer.
They let it sit over night and drove it in the mourning.
They tech. asked me to come in the next mourning and verify the noise.
The next day I came in and went for a test drive with the heavy line tech.
And of course it made the rattle noise at 4k rpm's when oil pressure was up and the motor was still in the cold range.
He said it sounded like "spark knock" to him which is detonation.
He also said he was going to call Ford tech hotline for help.
'They've had it for two more days now and no word as of yet.