Acceptable "piston slap"?

Hey all, being here in Wisconsin and the temps falling down to low 30s and 40s, I noticed some difference in my Lumina.

99, 3.1L with about 83,000 miles.

Anyway, when any of you start your Luminas in the morning, do you notice the rattling noise? I notice it in mine, even if the engine is warm and I restart it an hour later. Pretty sure this is fine, as my old 95 did the same thing.

When I drive it first thing in the morning, the engine sounds "stiff" or something...I didn't really notice this in my old lumina, it sounded the same when it was either just started or if it has been driven for awhile. This one makes a little noise when it takes off on a cold start.

Also, there is a certain RPM range where I can hold the gas at where I can make the rattling apparent at any temp? At idle, it is so barely faint you can't notice it (but I do just because I'm curious).

So, is this a normal characteristic of the later (or any) 3100 series Luminas? I know it's nothing to worry about, but I just like to know as much as I can because I'm just curious.

----AND also, (sorry)
I know sometimes the oil filter can make a slight (if any) difference in the sounds the car makes, so is there any preference you have for convential oil filters? Right now I just had my oil changed at a Valvoline VIOC.

Check out pistonslap.com, enjoy!

my 97 3.1 does the asme, as do most luminas ive been around

Yup. I've found if after starting cold and idling for 30 seconds or so, I raise the RPM's slowly to about 2500, hold for a few seconds, and then slowly lower back to idle, most of the noise goes away.

I've noticed the same noises in all of these I've ever been around.

My observation: If you leave the door open and start it cold, you'll probably notice that the motor is very quiet on initial start up, then gets noisier as it settles down to a slow idle. Then the racket increases as it warms up, but then suddenly trails off and almost disappears.

My rule of thumb with motor noises: If it hammers/knocks/rattles right at start-up, then gets quieter, something has excessive clearance and quiets down when the oil pressure hits it. This is worth worrying about.

But if it is quiet at start-up, and noise changes as it warms up, this is due to thermal expansion differences, and doesn't warrant alarm.

If you had one that the knock or slap got MORE noticeable as it reached operating temp and the oil leaned out a little, I'd be concerned.

But given the nature of these motors, and the known issues with these types of noises, I wouldn't worry about it if the pattern seems normal (quiet at start, noisy warm-up, quiet at operating temps)

My neighbor has an '04 Trailblazer with only 16,000 miles, and it slaps louder than my '97 with 122,000. So I guess they are carrying on the tradition to other engines now...

Well, thanks for the replies guys. :)

I was sure this was normal, the thing that got me concerned was I could hear the "slap" at low RPMs as well as at idle after throwing it in drive and driving it for a few hundred feet. I don't remember it doing this in the spring and summer months, so it just caused alarm. It always did make a little bit of noise at startup & idle though.

Yeah it always seems to get more pronounced as the temps start going into the 40's and 30's at night...I've noticed that too.