My '92 F150's 300 I6 has been making a rattling noise at a COLD startup...I've come across many reasons why it does this...however it has done this since day 1, had it a year, and I DRIVE it.
Reasons:
I've heard of 5.0 v8s doing this because of different materials that have to warm up.
I'm using the wrong oil filter...need the anti bypass type. (I've always used wix standard filters, a buddy said to try the racing filter...no difference in noise, just costs more)
It had a pushrod cover leak...I fixed it, but it became loose again (forgot thread locker) also they replaced my oil pan gasket/pan before I bought it and forgot the thread locker.< I think this is the problem because after I change the oil it will not rattle
could it be the oil pump not engaging right at start up?
One more question: is the oil pressure switch just for the gauge, or does it contribute more?
Normal wear and tear
loose bearing clearances
lack of oil at startup
If it doesnt do it for more then a few seconds at cold start there shouldnt be anything wrong just a well seasoned motor.
Try using a motorcraft filter.
My 84 3.8L did that after I had some work done on it a few years ago. He changed the oil and filter as part of the job. He used some brand X filter. The problem went away after I installed a Motorcraft filter.
I would buy a filter with an anti drain back valve. That won't let the oil drain out of the oil system and back into the pan while it sits. That would give you oil to the internals just a little bit fast at startup. Also I'd take the oil pans bolt out one at a time and reinstall them with thread locker.
found out some stuff!!!! The dealer put a pan on the truck before I bought it...LEFT BOLTS OUT...it's pretty well done g oil...also found out these engines are known for sludge build up in the pickup of the oil pump...
After you drop that pan and do some cleanup, switch to a Motorcraft or Purolator Pure One oil filter
I agree 100%... Also the 300s use timing gears and not a chain, they often get noisy. But thats more of a continual noise, if it just does it at startup get a good filter...
Only if its been neglected oil change wise... AFIK they are no worse tan any other engine... We ran ran a fleet of them at work for years (60-70 E150/250s)... Don't think we ever had a serious engine problem with any of the 300s... Can't say the same for the 4.2s though, before a couple years had passed we already had a couple that needed engines...