Is that noise located at the front of the engine?

... guessing that it might be related to the alternator. The alternator has bearings, particularly the front bearing, that wears out after so many engine hours. Also, it may be that you have put slightly too much tension on the alternator drive belt.

... Try loosening the alternator belt a little and see if there is any noticeable difference. Is the alternator new or has it been installed for some time? If nothing else, you could remove the alternator and have it tested at an alternator repair shop.

 

Never thought of that, the noise sounds like its coming from inside the engine but I can take another listen today. It's possible I have the belt a little too tight and its causing problems. It runs and drives perfectly fine except for those noises.

The first noise at cold start, could that be the starter not fully disengaging?

 

So I loosened the alternator belt but it didn't make a difference. Pretty sure the sound is coming from inside the engine, not from the accessories. I thought it might be an exhaust leak at the manifold but it doesn't sound like an exhaust leak.

As for the clacking noise at cold start, I guess it couldn't be the starter since it doesn't do it when its warm whatsoever. Only thing I can think of is oil not staying up in the engine enough... I'm running Rotella T5 10w-30 right now. I did 2 full engine flushes with Gunk's motorflush stuff for 5 minutes/each beforehand. The first flush came out black with only like 5 miles on the oil. The second flush was much cleaner.

 

How many miles on your engine?

 

Just over 122k miles.

EDIT: The engine had somewhat of a sludge buildup, but not the worst I've seen. Here's a pic with the valve cover off:

 

Let me know what you find. I'm working through the same issue. I'm hoping that it's not the dreaded "death rattle". Did the higher viscosity motor oil help ?

 

Will do. So far I've only ran the T5 10w-30 and it still does it. I want to believe that switching to a good 5w-30 would help at startup because its thinner, but its like 80 degrees out here so I don't think it would make a huge difference.

 

ADBV - Anti Drain Back Value

You might want to try an oil filter that has an Anti Drain Back Valve (i.e ADBV ). I think this prevents all the oil from flowing back to the oil pan once you shut off your engine. This way when you start up your engine after a long while, the oil will be higher in the engine. The oil will be doing it job sooner to prevent the friction at start up (i.e metal on metal rattling ).

 

I'm pretty sure the Purolator Classic filters have anti-drain back valves but someone else might know better? It does seem to be a problem with not having enough oil in the head on a cold start, it goes away literally as soon as it has oil pressure and then doesn't come back until well after its been cool. I'll try getting a different filter in there though and see what happens.

 

http://www.bobistheoilguy.com/forums/ubbthreads.php/forums/6/1/Oil__Filters

More than enough info on this site about oil filters.

 

So I figured out what the noise was... the beginning of either rod knock or a dropped valve. I finally handed it over to my father-in-law to drive, and it felt kinda weird on the way to his house, just kind of sluggish and weird. I thought maybe I had too much transmission fluid in it.

So he was bringing it back over the next day to check it and he didn't quite make it to my house before it started making horrible metallic noises and shutting off. I haven't seen the inside yet, but it sounds terrible (like a box of rocks), and there were fine metal shavings inside the valve cover. It did however make it home (about a mile), and it still starts and runs, even idles fairly smooth besides all the noise and vibrations. No check engine codes at all either.

Engine is halfway out right now, going to pick up a wrecked 99 Camry on Saturday for $500 to swap the engine out.