Would a piston rod knock all the time or would it be more pronounced when the RPMs go up? I have a knock when the trans. shifts from 1-2 and 2-3 at the top of each gear but it doesn't sound like valvetrain noise.

 

It would be there at all times and would increase with engine speed. It sounds like something may be hitting on your cars undercarriage since it seems to be happening under the most acceleration.

 

What would cause this my car only has 36000 on it. I hope thats not what it is. Would it change pitch as the RPMs go up? Its very nocticeable when the car is cold. I really can't discribe the sound though. A buddy of mine said he tought iwas coming from the top of the motor what else could make a knocking noise like that?

 

Spark knock, what kind of fuel are you running.

 

lifter?
Spark Knock, or detonation will sound like the proverbial coffee can with some nuts and botls being rattled around. And more so under heavier loads.

 

I'm beginning to think that it might not be a rod I put the car in neutral and reved it up and I only heard the noise at 2500-3000 rpms. What would a bad lifter sound like?

 

Ck your rocker arms needle bearings rod sounds like hammer against your block and more pronounced when you snap throttle queit on decell remove plug wires take the load off cylinder if noise gets quiet probably rod or pin

 

Are you sure this isn't a severe case of piston slap?

Good Luck,

 

im thinking the same thing, it might be piston slap. hope not though, keep us posted on what it is

 

I'll try that thanks!

 

If it is what then?

 

It is also very freaking loud.

 

Other things to check:

a) check your oil level, if its extremely low the car will make noise
b) double check all your spark plug and make sure none are loose, as this
will cause a compression noise that would get increasingly loud and fast the
higher your engine revs went
c) pull valve cover and inspect rocker arms, valvesprings, and pushrods.. a severely bent pushrod could really make the car sound alot worse than a valvetrain noise. A broken valvespring is not out of the question, but should be easy to see.
d) detonation.. are you running low grade gas? my suggestion to test would be to run high octane, and if it still makes the noise.. maybe try a mix of race gas to see if it cures it. If it does then you know what your culprit is.
e) exhaust leak.. but if its a knock your describing, more than likely this is not the case.
f) bent flex pate, or loose flex plate bolts.. if you have loose bolts from a convertor install it'll start out as a lightly audible knock that will grow increasingly louder as they become looser. If you somehow managed to bend the flex plate, it will also make a slight vibration and a knock. Do not drive around with a loose flex plate, as it will eventually cause damage to your torque convertor from the wobbling around. I know this from personal experience after a convertor stall in a 3rd gen.

If the sound is profound when you start it, and dies down a little when you let it
warm up.. then it could possibly be piston slap.

Does your car burn excessive oil?

Whatever the case, I wouldn't drive it much.. if your car is barely over 36,000 your dealership will more than likely warranty it.

Peace,

 

Thanks for the help I did just put in my Vig 3600 abd there is a little vibration but it was there before the install. I my car does use 1qt oil about 500-1000 miles before time to change it out. I also use nothing but Amaco 93 and I put Lucus injector cleaner in about every 4th tank. I will try to check the other stuff as well just to make sure.

 

Checked oil its good. The flex plate was fine when the stall was put in. I would think if the plugs were loose they would pop/blow out. I checked for anything loose under the car like exhaust, dipstick tubes for oil and trans. Its has to be in the valvetrain area. My car does have cold piston slap but its fine when its warmed up.