wierd knocking sound from ecotec...looking for input

[silver]

ok here's the deal....when I start my car at idle, it sounds like I'm getting lifter knock...I'm not 100% sure that the sound is coming from inside the engine but it sounds just like my corvettes in the past because they had lifter knock and it was well documented that it was normal and not to really worry about.

the sound doesn't change if I rev the motor, and when I rev the motor over about 2000 rpm...the sound goes away and doesn't return.

I'm just worried that there's a lack of oil pressure....could I be right?

[bolus]

Both darth and I have a very light knocking sound. barely audible over the engine when the car starts.  probably nothing

[MadMaxedAtom]

Mine has it too.Mostly after it's been run hard.I swear it's coming out of the transaxle,but since it's done it from day one (in my posession),I'm not very concerned.It almost seems like a gear rollover type noise in the trans.
Seems to diminish considerably when the clutch is disengaged.My Focus has a similar sounding noise and hasn't affected anything...in 115k miles
Don't worry...be happy.

[silver]

Thanks guys....I guess I got a little concerned because it didn't exist before I replaced the ECU, injectors and pulley....however, those can't have anything to do with it, and I was pretty sure nothing is loose, so I wont worry about it.

[MadMaxedAtom]

It actually sounds more like a rattle..rattle...rattle...rattle...rattle!

First time I heard it I though something had come loose,but twasn't the case

[gstatom]

Maybe piston slap...

[maverick1]

Guys I think I know what you're talking about and what causes it. Sometimes when I start up my Atom I get this rattling sound like ball bearings or pebbles in a tin can....does that sound familiar?
I think what is causing it is debris shaking around in the muffler. When I had to replace my exhaust I had to remove the muffler and when I did, I heard something rattling around inside. I believe it is this debris in the muffler that rattles around sometimes when I start the car.
Cheersâ?¢

[EricHowe]

Aaron, my ecotec did that too. If you remember it did it when we went out to the car show that night. Nothings happened since so hopefully it wont be a real problem.

[silver]

Mav, that's a different sound...when I had that sound it was because the gasket was missing between my header and downtube.  This much more like piston slap or lifter knock but still sounds like its normal.

Eric, I think I do remember that and yes it's exactly like that, it's just weird that it started now and not for the first 2000 miles.

[EcotecRacer]

if i remember correctly this should be normal i belived its caused by the timing chain slack adjuster. it runs off of oil pressure. Ecotecs use timing chains which in turn produce more clicking noises.

[foobar12345]

[quote="maverick1"]
Guys I think I know what you're talking about and what causes it. Sometimes when I start up my Atom I get this rattling sound like ball bearings or pebbles in a tin can....does that sound familiar?
I think what is causing it is debris shaking around in the muffler. When I had to replace my exhaust I had to remove the muffler and when I did, I heard something rattling around inside. I believe it is this debris in the muffler that rattles around sometimes when I start the car.
Cheersâ?¢
[/quote]

Maverick,

I believe you are right.  I took my muffler off and shook it around dislodging some of that metal inside of it.  Now it sounds horrible with all of those metal fillings shooting around inside the muffler but no noticable performance difference.  Its only noticable at idle because the engine isnt generating enough noise. I'm going to make a straight pipe similar to Randy's and take the muffler out of commission until Ray or someone else comes up with a low quantity header/exhaust replacement. 

-Brad

[silver]

There are two different issues here, I was there when you shook your muffler Brad, and so in turn I shook mine when it came off...yours sounded like it had lots of chunky material inside, mine sounded like it had a little sand inside, not enough to cause the noise.....so I'm thinking we've got two different gremlins here.

[maverick1]

Guys, now at idle my muffler is making all kinds of funky vibrations and is on it's last leg. Is there anywhere to buy a replacement muffler for the Atom besides Brammo, or do you need a custom one?
cheers

[silver]

it's not a critical part to the car, so I'd recommend you make it home and then wait until we have the new exhaust designed then get that.

But, just to be sure you should still check your header to downpipe gasket and other gaskets to make sure they are not the source of the problem.....if it's just the muffler, you can go to any muffler shop and have them replace it...just stay away from retail muffler shops (midas) go to a "joe's mufflers" or something like that to get legit service

If you can however wait I would recommend waiting until we have the new one ready to go.

[MadMaxedAtom]

There is nothing wrong with  "chain" muffler repair outlets.
They are independantly owned by "Joes" and "Janes" and employ local mechanics and stand by their work 100%.They are well equipped to handle any exhaust situation,with custom bending machines,welders and components,and are usually better than your local Billy-Bobs do-it-all repair facility,who buys stuff off the rack.
Two of my very good friends run two locally.
Please don't buy into the stereotyping crap floating around.