4.6 Knocking sound at idle on cold start?

[crescent_wrench]

Seems that this issue has started in the last few weeks. Here are the details: -24k miles -bone stock engine, original owner -change oil every 5k, only use Motorcraft oil filters -only does it at idle and seems to go away after 10 minutes of running -doesn't matter if it's cold or hot outside -no warning lights, car runs fine Never had this problem before. Almost sounds like a rod knock....that goes away when warmed up. Not too loud, but there. I googled this, and seems like this happens to many ford modular motors. Some link/posts say folks have even had their motors replaced under warranty for this. I'm just wondering what to do as my warranty will expire next year. Anyone else heard of this or have this happen to them? Thanks for any comments.

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[rollintechno]

I dunno man. That's a very unsettling sound though that's for sure. Good luck on getting it figured out or fixed.

[sand storm]

I have an 08 GT stock except for a tower brace and cold airkit. Has 11k miles. Did the same. Switched to mobil 1 5w30 from Motorcraft oil and no more knocking. Buddie of mine had similar issue and it was a loose fly wheel...yes hard to believe but was loose. Gremlins do exist! Good luck.

ev

[crescent_wrench]

Actually I forgot we have a 5/60 powertrain warranty. I'll take it in....even though the dealer will say it's normal.

[DaMach04]

If it is going away after it gets warm, check all your seals and gaskets. Mine made a weird noise about a year after having headers put on, that went away after it got warm. The gasket between the head and headers had a hole it in. When the gasket got warm it expanded just enough to seal the hole up so the noise went away after a few minutes of driving.

Eventually it got worse as the hole got bigger. Have it checked ASAP!