Odd Knock

[96gsdsm]

After doing freeway pulls (it doesn't seem to do it anyother time i.e. drag, AutoX, etc. etc.) When I've really been giving it to the car, it makes an odd knocking sound.... it almost sounds like a really bad rod knock coming from one of the cyclinders.

I can't determine weather or not it's coming from the block or head.

Here's the odd part. It only lasts untill the engine cools down (shut off for a 1/2 hour ... or mild driving for 1/2 hour to 45 minutes) then it completely goes away.

The motor is almost brand new, (4-5k miles) I had in 4 quarts of royal purple 10w 30... then when it happened for the first time immediately gave it an oil change (1 part Lucas to 4 parts 10w30 royal purple) and it still does it.

I do have 1 sealed power (advance auto brand) lifter (which looks to be a 2nd gen revised) but I don't know that that could have anything to do with it.

Any ideas?

 

[arash15]

Do you have a log, what are you using to tune? How much knock retard are you getting? Check compression and do all the obvious checks, (especailly base timing)

 

[96gsdsm]

Do you have a log, what are you using to tune? How much knock retard are you getting? Check compression and do all the obvious checks, (especailly base timing)

Timing is dead-on. Compression is 160-160-160-160. I'm running 1 step colder plugs right now, and have tryed running 2 step colder plugs with no success. No boost leaks.

I'm not seeing knock retard..... mainly because I'm not knocking.

My mods are in my profile, and are kept up to date.

 

[arash15]

Timing is dead-on. Compression is 160-160-160-160. I'm running 1 step colder plugs right now, and have tryed running 2 step colder plugs with no success. No boost leaks.

I'm not seeing knock retard..... mainly because I'm not knocking.

My mods are in my profile, and are kept up to date.

So the engine is making a knocking sound and the knock sensor is not pulling timing. Are you sure you havent mistaked the sound for lifter tick? What are your plugs gapped at? What condition are your spark plug wires in? Have you checked to see if they are arcing? Have you done a boost leak test? I wouldnt use oil additives, personally i would stick to synthetic 10w30.

 

[96gsdsm]

So the engine is making a knocking sound and the knock sensor is not pulling timing. Are you sure you havent mistaked the sound for lifter tick? What are your plugs gapped at? What condition are your spark plug wires in? Have you checked to see if they are arcing? Have you done a boost leak test? I wouldnt use oil additives, personally i would stick to synthetic 10w30.

I am running synthetic 10w30... I've tryed both with and without additaves. (lucas)

After looking at some more logs the engine is both making knocking sounds and pulling timing. Basic stuff is well taken care of....

I already said I'm not boost leaking, nor do boost leaks make knocking sounds nor do improper spark plug gaps. There is no arcing.

As soon as I get some extra money I'm going to replace all the lifters with 3g revised ones to see if that solves it.

 

[Nors]

Okay, this may seem out there but I have seen cars with wierd knocks etc and it has been things like loose PS pumps, loose alternators, various things like that. Sometimes knock sensors would even pick up these knocks and the car would have no balls at all (ecu pulling abunch of timing). None of these were DSMs but I am just throwing ideas out there. So I would check everything to see if it is secure.

 

[96gsdsm]

Okay, this may seem out there but I have seen cars with wierd knocks etc and it has been things like loos PS pumps, loose alternators, various things like that. Sometimes knock sensors would even pick up these knocks and the car would have no balls at all (ecu pulling abunch of timing). None of these were DSMs but I am just throwing ideas out there. So I would check everything to see if it is secure.

With the engine running and hood open, I can clearly hear it coming from the motor, but because of the internal shape of an engine block, it's hard to tell exactly where it's coming from. I am absolutely positive it is coming from the motor though.

I just posted this in case someone had similar problems with noise and load.

 

[Nors]

Oh okay, well a trick is to take like a foot of vacuum hose and put it to your ear and start putting it on different areas of the engine. A long screwdriver also works decently well, or you could get a mechanics stehoscope. However you do it just watch for moving parts/belts/fans. That should help you narrow it down to the head or bottom end atleast.

 

[turborebel]

The mechanics stethascope will work best. Any auto parts store should have them and for about $30, it's a good thing to have around.