I hate to post the same thread in two forums, but I posted this the other day down in the engine forum and haven't gotten any responses. I figured since more people look at this forum might get some insight.

The other day my engine started making knocking sound. It's louder when I first start the truck cold in the morning, then quietens down. It seems to occur mainly in gear and on acceleration between 900 - 1500 RPMS. I have pretty good oil pressure and the needle doesn't jump around at all. It's about 60 psi cold and after warming up at idle its around 27-30 and goes up to between 40-45 when actually driving. I took a quick video this morning driving through the parking lot at work. You may have to turn your speakers up, but you can hear it tap/knock when I accelerate about 6 secs into the video again at 20 secs and then again about 40 secs in the video. I revved the engine after putting it in park to show it's not really there at that time, I'm confused? It's like a hollow type knocking sound. Any insight would be great.

Edit: I use Rotella 10W-30 oil, and sometimes Rotella 15W-40. I did already pull the valve covers and check all the rocker arms and push rods and didn't see any issues with either. I ran it with the valve covers off to verify oil is circulating up through all the lifters and pushrods too.

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What you describe sounds alot like a labor knock. Check your timing. Might try checking vacuum advance also.

 

I couldn't tell what you're talking about because you're on a gravel lot and something is rattling (unless that's what you're referring to - but that didn't seem to track RPM, in which case oil pressure and such isn't of interest).

Does the noise track RPM? If so, everything you're describing sounds like spark knock, with the exception of it quieting down as the engine warms up - spark knock is almost always absent cold, and gets worse as the engine gets up to temp. So based on that, and not being able to tell from the video, I'm not really sure what you're facing.

Nice sounding exhaust, BTW.

 

Yes it does track with RPMs when it does it. I'll try to get a better video in the morning on the pavement when it's cold and louder and the doors and crap ain't rattling. LOL

After your suggestion I checked the timing it was a little high, I thought I had set it at 13^ but it was at about 15 so I backed it down to about 11^ to see how it reacts.

Thanks for the compliments on the exhaust, it's Summit brand full length headers to 2 1/4 pipe into Flowtech Raptor mufflers that dump under the bed before the axle.

 

Ok, here's a better video I took this morning. You can clearly hear the sound I'm talking about at about the 1 minute mark when I take off from the stop sign in front of the school.

302 knocking - YouTube

 

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I did have a couple of FE engines that had a similar knock; with them it turned out to be the fuel pump. It was a weak return spring on the rod that runs on the cam lob.

 

I'm listening to this on my phone so I may not be hearing correctly. Sounds like the fuel pump. All the cheap mechanical pumps these days seem to knock.

 

Couldn't hear anything in the video but something rattling.

I had a cam lobe and lifter fail one time in a 351W engine. It would make a rather loud tapping noise but if I remember correctly it did it all the time. Not just under certain conditions.

Unfortunately the noise could be caused by all sorts of things as it is hard to describe a "knock".

Does it do it sitting in the driveway at idle or if someone revs it up for you so you can look in the engine bay and try and find out where it is? Using a large screw driver as a stethescope can help pinpoint it.

 

I have tried to listen under the hood while my wife revved it up and I couldn't tell where it was coming from. It kinda sounded like it was coming from low on the back passenger side, so I layed under the truck to see if I could hear anything and couldn't hear it from down there?? IDK I think I'll just drive it till I can't anymore then put a roller Explorer motor in it.