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Weird Chattering Noise Under Moderate/Heavy Acceleration

2004 Lincoln LS V6 3.0. 108k miles.

So last time I posted here I was asking about low compression on cylinder #1, link here: (Very Low Compression), and after running Engine Restore and Rislone Ring Seal through the engine for about 50 miles, the idle has smoothed out and there are no longer any misfiring codes, in fact there aren’t any trouble codes at all! (Hurrah).

Reading the last post (link above) may help with diagnosing this. . .
Accelerating to 2500 rpm and above before the motor is fully warmed up causes a nasty sound, almost like you can hear all the individual valve sounds amplified, or like the timing chain is chattering loudly at the pace of the engine. The sound disappears as the gas pedal is released, but it happens (albeit more quietly) even when the engine is warm. My timing chain is at 100k+ miles now, but the tensioners are brand new. Before piston #1 slapped a valve this sound was happening with the original cylinder head after I redid the timing of the engine, and after I replaced the cylinder head the sound still happens, so it can’t be rod knock or piston slap, right? Maybe inadequate oil supply? Worn timing chain and guides? Spark knock? I redid the timing in the first place because a while back bank 2 threw a code saying timing was over-retarded, and after resetting the timing this noise problem started which happened simultaneously when timing was thrown off and piston #1 hit the valve (in link posted above). I will be replacing the timing chains soon anyway because last time I heard this noise my timing was thrown off on bank 1 causing misfires and eventually piston #1 slapped an intake valve and destroyed the original cylinder head.

For simplicity here’s what happened in order:

  1. Bank 2 threw code saying over-retarded timing.
  2. I reset timing chains and weird chattering noise started happening under moderate/heavy acceleration when motor is cold (and slightly happens when warm).
  3. Eventually timing was thrown off on bank 1 at the same time as the chattering noise began causing misfires and piston #1 to hit intake valve.
  4. Replaced damaged cylinder head and fixed low compression on cylinder #1 as well as reset timing again.
  5. Engine still makes weird chattering noise under moderate/heavy acceleration.
  • And so I’m afraid timing will be thrown off again and another valve or cylinder head will be destroyed. So my question is, does this sound like a worn down timing chain and guides?

Two possibilities come to mind. 1. Old fashioned knocking. 2. Lack of oil to upper engine.

To find out, remove a valve cover to watch the valve action.

Get on crank bolt with a breaker bar/socket and turn the engine by hand in the normal direction.

Now turn the engine over in the opposite direction while watching the valves.

If the engine can be turned 5 degrees or more in the opposite direction before any valve movement is seen, indicates a loose/stretched timing chain.


It wasn’t knocking/pinging ever before I adjusted timing the first time, could correcting timing cause that level of knocking? I think lack of oil to the top end could be an issue but I’ve always had a good oil level and correct grade, and the oil light has never come on either.

Any chance of an EGR system fault? Those can occur without setting a DTC at all.,

I can pretty much guarantee it turns 5 degrees counter clockwise without changing valve position, that’s one of the first things I noticed when adjusting timing was that there seemed to be a little too much slack on the untensioned side of the crank gear. The noise never happens when in neutral or park, I forgot to mention, so I don’t think I’m experienced enough to diagnose if it’s the valves by taking the valve cover off. It’s always when in gear and accelerating moderately and beyond, when engine is under load I assume.
With a ton of research I found new chains with the correct length of 136 links (rock auto stocks incorrect 144 link chains), so I’m praying that fixes the issue. . .

Do EGR faults usually cause other noticeable symptoms?

It’s certainly possible. Back in the day you could eliminate knock by advancing the ignition timing so that the spark plug would fire before the knock had a chance to take place. You could also have a bad knock sensor. Try a tank of premium and see if it mitigates the problem. If so, you’re hearing old fashioned knocking.

The second worst problem with an EGR fault is clattering under acceleration. The first and most serious fault is that if this is an EGR system problem it MUST be fixed.

Clattering because of a faulty EGR can destroy an engine. I know. Over the years I’ve purchased a few nice cars on the cheap because a piston got holed due to pinging. A couple of friends of mine who built high compression engines with no EGR and far too advanced timing also found out the hard way what clattering will do. Ruined their engines in less than 150 miles.

I never thought about the knock sensor, and I probably should check that out, however I’ve always used 91 or 93 octane in this thing which the vehicle recommends 91 for. What I’ll try first is new timing chains to see if it fixes the noise.

I’m definitely checking my EGR system then, but is the clattering caused by a stuck open valve or stuck closed valve?