Light engine knock?

[Custom Trendz Inc.]

Heard some light engine knocking today, or exhaust knocking, dont know which at the time since its late here and neighbors have the windows open. But it was only possible to hear it at idle, it was sort-of rhythmic but would dissapear once i pressed the gas. could it be the heat shield? absolutely no engine warning light, and i plugged a obd2 reader today and it had no codes. 125k miles, no leaks or oil anywhere, oils fine, no dents in oil pan, doesnt run hot, and spark plugs and wires are new.

 

any clue at what i should look for tomorow?

[Platinum_Racing]

Could be noisy valves. Do an oil change with some Marvels Mystery Oil or Engine Restore additive and wait 50 or so miles to see if it goes away. I find that using 10W-40 oil in older cars in warm weather gets rid of any small noises and reduces any oil consumption. In cold weather, switch back to 10W-30. My Legacy doesn't burn or leak oil, nor does it make any strange noises, but I still find that she likes 10W-40 more than 10W-30 during the summertime.

 

Could be piston slap. Unless this car has a ton of miles this is unlikely, especially since it goes away off-idle.

 

Could be a noisy injector. They tend to get louder as they age. Again, since it seems to go away off idle it seems unlikely.

 

Could be a heat shield, but it would be more of a sheet-metal type rattle than a knock. Not only that but you would hear it driving over bumps, or even while driving in general.

 

 

 

My suggestion would be to use the old screwdriver trick. Take a flat head screwdriver with a plastic handle. The longer the better (That's what she said... ) With the engine running, place the metal screwdriver tip against each of the 4 fuel injector covers. Place your ear GENTLY against the plastic handle of the screwdriver. If you can't identify the noise, move to the valve covers and cylinder heads and listen again. If you can reach the block, listen there too. If you locate the source of the noise you'll know it without a doubt. It will be the same frequency, intensity, and rhythm only amplified. This trick is also cool because you get to hear lots of things you don't usually hear.

 

IMPORTANT NOTE:

STAY AWAY from the spark plug wires, the coil pack, and the spark plugs. I know the plugs are kind of out of the way on the 2.5L, but still, stay away. In fact, stay away from any of the ignition components. Don't be afraid to go a couple inches away from the spark plug wires, but don't touch them. If you feel unsafe or unconfident, don't to this trick. Its safe to do, but you need to stay away from the ignition. This is my disclaimer. Now if you hurt yourself you can't send a lawyer to my house to serve me with papers.

[Custom Trendz Inc.]

well my manual said 5w-30 so thats whats in there now. knock is surprisingly gone, maybe it was just the heat shield slightly hitting since i took one of the mounts off that was broken(close to the front.) Original owner welded it back together but then it broke off once again. Thanks for all the advice if the noise comes back ill definately make sure I do that trick.

 

Problem at the moment is my fuel gauge is off, filled a tank that was less then 1/4 and it only filled the tank with 8.6 gallons of fuel. Have to wait till the tank is close to empty to put in some techron(heard that works) and if not then ill check to see if the float/sender assembly is messed up at all.