1k RPM clatter

[88lance]

Did a search, but haven't found much about this specific situation.

2002 Tahoe, 5.3, 217k miles. The 5.3 has has a quiet clattering sound right around the 1,000 rpm area. If you don't have the radio on, you notice it.
Temp doesn't seem to matter, it was hot today and I ran errands for a few hours, and it never goes away.

Oil is almost due for change, but level is still good.

This 5.3 does have the cold morning knock that some of these have, which goes away after a few minutes. It makes me wonder if this is part of that same cause.

Is there something preventing sufficient oil from getting to the top end at that rpm or something?
Is this just one of those "normal" things that you can just ignore, and never really does anything?

 

[strutaeng]

Hard to tell just by your description: could be exhaust/cats, transmission, flex plate, lifters or top end, bottom end, accessories, and who knows what else?

I once had what I was pretty sure was a rock knock. Turned out to be a muffler that had rusted through and was making the sound. $150 at the muffler shop for a new resonator and off I went.

A $7 HF stethoscope is worth every penny when trying to pinpoint sounds.

 

[Doubeleive]

Did a search, but haven't found much about this specific situation.

2002 Tahoe, 5.3, 217k miles. The 5.3 has has a quiet clattering sound right around the 1,000 rpm area. If you don't have the radio on, you notice it.
Temp doesn't seem to matter, it was hot today and I ran errands for a few hours, and it never goes away.

Oil is almost due for change, but level is still good.

This 5.3 does have the cold morning knock that some of these have, which goes away after a few minutes. It makes me wonder if this is part of that same cause.

Is there something preventing sufficient oil from getting to the top end at that rpm or something?
Is this just one of those "normal" things that you can just ignore, and never really does anything?

take the belts off, both serpentine and ac
start it up and run it for a minute revving it a little to see if the rattle is still present or not.
if it is then it's internal or a cat broke apart or a heat shield is loose, starter, etc.
if sound is gone, put ac belt back on try again
if noise is present then ac pump is going out, they often sound like a can of loose nuts-n-bolts inside
if still no noise spin the remaining pulleys by hand and see if you can find the source
if nothing found
put serpentine back on, carry on and maybe grab a mechanics stethascope and investigate further.

 

[88lance]

Good points, I was thinking lifters from the sounds of it, but hard to tell. I'll get under the hood tomorrow and see if I can track it down, maybe it's something more simple.

 

[Alex_M]

How many miles on it? Edit - just saw the mileage. Over 200k is around when this seems to often start happening.

The knocking at start up is most likely oil pump o ring. Takes it a minute to get primed after it drains off over night.

The low rpm clatter I've heard attributed to piston slap. Not a huge deal, just starts to happen more on higher mileage rigs. The oil pump o ring is one you should probably start planning to take care of. In the mean time, don't put any load on the motor till the knocking goes away; just let it idle and that will minimize wear.

 

[88lance]

Thanks. I do let it sit and idle a few minutes before taking off usually, for that reason.
Good to know the clatter is probably something that's not damaging anything.
Going to look a little closer into it this morning in case it is something different, like what's mentioned above.
what are y'all's thoughts on additives in the oil changes? I heard not to use cleaners in there, but what about something like Lucas to throw in?

 

[OR VietVet]

You heard the noise before and on a cold start it was louder and then went away and now does not go completely away. The lifters are not staying completely pumped up and/or you now have high mileage "give up the ghost" age problems and worn cam. If the truck is straight and this is the only major problem and you like the truck and it meets your needs, fix it.

 

[88lance]

You heard the noise before and on a cold start it was louder and then went away and now does not go completely away. The lifters are not staying completely pumped up and/or you now have high mileage "give up the ghost" age problems and worn cam. If the truck is straight and this is the only major problem and you like the truck and it meets your needs, fix it.

It seems to be different from the cold morning piston slap. The cold morning piston slap happens for only a few minutes, and is gone.
The clattering seems like it won't show up until the motor is warmed up, and is more of a "clatter" than a piston slap.
Sounds like two different things, after further listening.
I'll get it warmed up with some driving this evening and then see if I can track it down a bit further.

 

[Doubeleive]

Thanks. I do let it sit and idle a few minutes before taking off usually, for that reason.
Good to know the clatter is probably something that's not damaging anything.
Going to look a little closer into it this morning in case it is something different, like what's mentioned above.
what are y'all's thoughts on additives in the oil changes? I heard not to use cleaners in there, but what about something like Lucas to throw in?

we call that "snake oil" but if it quiets it up I guess that's easier on the wallet than a new engine