knocking. A lot of it (1 Viewer)

[hammerheadfistpunch]

Getting concerned that the rattle I hear a lot in my cruiser is knocking. Im not sure why it would be, spark plugs are new and gapped properly, trim is good, O2 sensors are new, no codes...

Thoughts? The noise Im looking for is the rattle on overrun. This happens a lot when cold and under part load.



I'll try and get a better sound clip.
Here is a MUCH better clip, you can really hear the rattle. Its here on the overrun but its present under light load and especially when cold. My hope is that its just the cats rattling apart ("just"). But it sure sounds like knock. Can the knock sensors be bad and it not throw a code?

 

[hammerheadfistpunch]

Could it just be valves out of adjustment? They were done ~80k ago.

 

[steffan]

sounds like a rattle - timing chain?

 

[hammerheadfistpunch]

sounds like a rattle - timing chain?

Comes from the back of the engine more than the front. And manly on the exhaust side

 

[inkpot]

Is the baseline ignition timing set too high?

 

[hammerheadfistpunch]

Is the baseline ignition timing set too high?

Possibly, it idles at 4/4.5 and spends most of its time in the 13-17 range.

 

[BILT4ME]

Check your O2 sensors. May be loose or leaking.

Otherwise the guard on exhaust under the fender.

Also could be a manifold leak.

 

[hammerheadfistpunch]

Check your O2 sensors. May be loose or leaking.

Otherwise the guard on exhaust under the fender.

Also could be a manifold leak.

It was going this before the new o2. I'll check the others though

 

[dugsgms]

Hard to say w/o being there but sounds like a exhaust leak to me.

 

[Tools R Us]

Stethoscope, where is the noise coming from?

 

[inkpot]

Possibly, it idles at 4/4.5 and spends most of its time in the 13-17 range.

I’m talking about where you set the baseline timing by putting a jumper in the diagnostic port and using a timing light to illuminate the crankshaft at the timing chain cover. Adjustments are made by rotating the dizzy?

 

[Bludozer]

Get an automotive stethoscope. These are worth their weight in gold.

Can't really offer you much more advice than others have given though, many much more knowledgeable and technically inclined posters here.

 

[Comet]

I would shut the truck down, get under, and smack everything with a rubber mallet. Whatever rattles gets tightened. After that, I would follow the line @inkpot has recommended. Jump diagnostic port, retard timing a little, see if it still rattles as much. It sounded like the rattle was more under load and not as much at idle.

 

[hammerheadfistpunch]

whoa this is a smart group! You guys got my number on that one!



Banged away on the heat shield just before the cats and smashed it good till it shut up. Still makes other noises that I think are a leaky exhaust at the trash can...er...stock muffler that I think combined sounded exactly like knock. Much better now though and i feel much less paranoid.

Now to get the cooling system sorted and im set!

 

[hammerheadfistpunch]

Hard to say w/o being there but sounds like a exhaust leak to me.

Well its that too.