i noticed the other day that when i accelerate and put it to the floor, i hear a slight knocking noise. Anybody know what this could be? i just changed my oil and it is still doing it.

 

my dads truck used to do this ever since we got it in '93. it was a '92 f-150 with a 351w in it...eventually the motor blew when we were going fishing riding down i-20 and i think it ended up being a blew rod bearing. try putting a quart of STP oil treatment in your truck. if its only a slight knocking this should calm it down

 

Does it do it only when you are in drive, or even when you rev it in park? And does it only do it when you accelerate hard?

 

If it's only doing it at heavy throttle? It could be a problem with timing / octane / carbon build up.

First, try running a tank of 92-93 octane. If it goes away then you'll know that's the problem. If it's still there.. then its something mechanical.
Second, I'd suggest running a straight 30w oil.

Rich

 

i'm not sure if it does it while i have it out of gear...i will have to check on that. to answer your other question, yes, it only does it when i put it 3/4 or more to the floor. i will try running a higher octane and see what happens. so what happens if the sound dissappears after i use a higher octane, does that mean i should use 92-93 octane all the time?