I live up here in cold Canada, and when I start up my truck with the factory car starter, at -1 to -30 degrees celicius, and let it run to warm up, by the time I get to my truck, I can hear a knocking/ticking sound coming from the engine, but then you drive it for a while the sound is gone?????? It doesn't do it at first start up, but after roughly 5 minutes. Does anyone know what this is? and I know it's not piston slap, because I know how that sounds like. Anyone else have that issue, I was also told it is also due to low oil pressure, on a new truck???
It is a 5.7 hemi w/MDS....

 

could be a small exhaust leak and then when the motor and everything warms up the metal expands closing off the leak, maybe the doughnut gaskets?
happened in my fathers f-150, he was freaking out thinking his motor was going bad and turned out to be a exhaust manifold leak, which went away when his motor warmed up.

could also be lifters tapping? maybe try some lucas oil stabalizer, stuff works great imo.

have you tried listening for the noise with the hood up and maybe get underneath the truck and try to pinpoint where the noise is coming from.

good luck

 

DON'T Put the Lucas in a 06-up hemi. It is way too thick for the MDS and will cause problems.

 

mine does it too when its cold out. mine sounds more like lifters.

 

I've been noticing it on startup, too. It sounds *almost* like a compressor belt running, or something, but I don't have the AC on. I've got a Flowmaster series 50 exhaust on it that's about three years old, so I was also thinking it could be the exhaust starting to go bad. From my experience, Flowmasters only last a couple of years, so I wouldn't be surprised if that was the case. Sometimes it seems like it's coming from the back, but I'm pretty sure the noise is coming from the front, though.

 

What are you running for gas? If it's regular 87, try 89 octane and see if that makes it go away. Your engine might not be so tolerant of the lower octane in the winter blends.

 

I always use mid-grade in my truck religiously, which is 89 everywhere around here.

 

I recomend running a good synthetic oil. It makes alot of noises quieter. Run 89 oct gas.

 

Mobil 1 5/20 always since after break in.

 

Thanks guys for the help, I appreciate it. I'll try running 89 octane in her to see if it stops the noise, I checked for a exhaust leaks, and everything is fine, I could not find any leaks at all. Do you guys know when is the break-in period with these hemi's? I heard it's around 100 000 kms's. Is it?