Engine sound when accelerating

[jaguarjoe]

When you punch our '02 4.2L TB LT EXT, It sounds like 24 marbles rattling around in a 48 marble can. Seriously, it sounds like spark knock except on. 6 cyls.

If it was knockinng that bad, the knock sensors would be screaminng.


Any ideas??

 

[The_Roadie]

Ever get a code or flashing CEL? How many miles, and are your plugs the right kind and changed at 100K? Fluids OK? You could always pull the serpentine belt for a minute and try it to see if it's a rotating bit onthe front of the engine. The water pump comes to mind, along with anything else with bearings up there. If it's proportional to road speed and not engine RPM I think you would have mentioned that. Happen only under load, or when you rev it up in neutral? Have you inspected the exhaust manifold and muffler shields? They love to rattle if loose. Interior damage in the muffler and cat could also rattle. Fan clutch? Lots of possibilities. See if any of them jump out at you when you're standing still and just rev it up.

 

[meerschm]

Water Pump.

with the vehicle off, see if the fan moves in any way other than round and round.

you also can have some one gun it while you listen under the hood.

(be very careful, so you do not let any part of your body or clothing near the moving parts)

 

[jaguarjoe]

Funny enough, I'm set to do the water pump tomorrow.

No CEL light, not even a blink.
TB only has 67k on the clock, a bit early for plugs. Being dealer maintained prior to my ownership, I'd hope they used the right plugs if they changed them.
You can hear the muffler shield chime in at a higher RPM.
Don't know if it occurs at no load, will find out tomorrow.

In the last 10yrs, PO has spent about 8 kilobucks maintaining this thing at the dealer.

 

[The_Roadie]

In the last 10yrs, PO has spent about 8 kilobucks maintaining this thing at the dealer.

Are you convinced looking at the records that more than 1/4 of that was justified and the dealer scaring the owner into unnecessary stuff?