annoying knocking

hey everyone, I have this real annoying clicking or knocking noise that comes from either under my silverado or under my hood. But after my truck gets warmed up I dont here it anymore. I can only hear it when I am next to either anothe vehicle while it is warming up or next to a building. Any of you have any idea what this could be.

Probably a little piston slap... nothing to worry about http://www.automotiveforums.com/vbulletin/showthread.php?t=414390&highlight=knock

You may want to read this.

http://www.pistonslap.com/

You may want to read this.

http://www.pistonslap.com/

Oh, good God, not this crap again...

hey everyone, I have this real annoying clicking or knocking noise that comes from either under my silverado or under my hood. But after my truck gets warmed up I dont here it anymore. I can only hear it when I am next to either anothe vehicle while it is warming up or next to a building. Any of you have any idea what this could be.

Wait... what year is your truck?

I'm curious Blender; do you have piston slap?

I'm curious Blender; do you have piston slap?
So is piston slap NOT normal? That is what that site is saying

I'm curious Blender; do you have piston slap?

Like I've said before, I do not have piston slap in this truck, but I would say that at least 4 out of 5 of my previous vehicles had the "knock" at startup. Those include some Chevys, a Dodge, a couple Hondas, and a couple Fords. Anyway, we've had this debate before, and I don't want to open it back up is all I was saying.

Like I've said before, I do not have piston slap in this truck, but I would say that at least 4 out of 5 of my previous vehicles had the "knock" at startup. Those include some Chevys, a Dodge, a couple Hondas, and a couple Fords. Anyway, we've had this debate before, and I don't want to open it back up is all I was saying.
Is the old one still one here, because i nerver saw it.

Just making sure you had some frame of reference/experience with this problem. Mine
had it, but I think I found a cure; at least for me. I run Royal Purple and a K&N filter now, and am happy to say I have had zero piston slap since. I've been using that combo for the last 14,000 miles with success. Not sure if it "cured" it, but sure better than the standard GM answer "short skirted pistons are supposed to make that noise". BS.

Just making sure you had some frame of reference/experience with this problem. Mine
had it, but I think I found a cure; at least for me. I run Royal Purple and a K&N filter now, and am happy to say I have had zero piston slap since. I've been using that combo for the last 14,000 miles with success. Not sure if it "cured" it, but sure better than the standard GM answer "short skirted pistons are supposed to make that noise". BS.

My truck is at 34,000 miles, and i have been using RP in mine for ~5,500 miles. Maybe why that is why mine doesn't

My truck is at 34,000 miles, and i have been using RP in mine for ~5,500 miles. Maybe why that is why mine doesn't
Ya i here that on alot of people's cars. They run a synthec in it and it will stop.

RP is some good stuff (I'm a dealer, so naturally I'm biased). I still firmy believe that you MUST run a high quality filter in addition to syn oil. Fram just doesn't cut it.

I'm going to go with a Purolator Pure One next time around. Here's some more people's opinions http://forum.ls1truck.com/index.php?showtopic=4931&hl=royal+purple

I agree with that filter choice. K&N, Baldwin, Purolator, Wix, Fleetguard, are all great choices. Can't say I agree with some of the postings on that board about RP though. I have NEVER read anything but positive remarks about the product; at least remarks that had actually proof behind them. It's amazing how people can debate oil all day.

So is piston slap NOT normal? That is what that site is saying

Piston slap is usually normal on cold startups on engines with forged pistons and wide ring tolerances,(i.e high compression motors) but you wouldn't think it would be a problem on brand new modern day vehicles. I don't have any real experience with this, other than what I read (My truck doesn't have this problem either), I was simply making you aware of what could be an answer to a potential problem you could be having and let you draw your own conclusions. You'll probably have to do a little more research on it on your own and do what you think is best. You have to be careful of people who are such "Die-hard" Chevy fans, that they'll never acknowledge things like this can be possible, so they'll just dismiss it as "Nonsense", since Chevy would NEVER have a problem like this. Do your own research, and come to your own conlcusions, since nobody here but you is going to be paying the repair bill if anything happens. It's your truck.

Piston slap is usually normal on cold startups on engines with forged pistons and wide ring tolerances,(i.e high compression motors) but you wouldn't think it would be a problem on brand new modern day vehicles. I don't have any real experience with this, other than what I read (My truck doesn't have this problem either), I was simply making you aware of what could be an answer to a potential problem you could be having and let you draw your own conclusions. You'll probably have to do a little more research on it on your own and do what you think is best. You have to be careful of people who are such "Die-hard" Chevy fans, that they'll never acknowledge things like this can be possible, so they'll just dismiss it as "Nonsense", since Chevy would NEVER have a problem like this. Do your own research, and come to your own conlcusions, since nobody here but you is going to be paying the repair bill if anything happens. It's your truck.
Ya i have it on my trans am it has a ls1 and i know the compression is high on this motor. But it mostly does it when i frist start it up. I will try running a synthec oil in it and see what happens.

It could be yourr air conditioning. When I was buying my truck and had it inspected I too noticed the clicking/knocking noise. I asked the mechanic what the clicking sound was and he told me that it was the air conditioner and that some are louder than others. perfectly normal tho.

I agree with that filter choice. K&N, Baldwin, Purolator, Wix, Fleetguard, are all great choices. Can't say I agree with some of the postings on that board about RP though. I have NEVER read anything but positive remarks about the product; at least remarks that had actually proof behind them. It's amazing how people can debate oil all day.

Yeah, I posted over there, and I sort of ignored the bad ones... I know how it acts in my truck, and, frankly, what more do I need to know?

I had a very small clatter at startup when I first bought an 01 LS truck 2 months ago with 38K on it. I only noticed after reading the forums, I paid attention and it was there. I switched to Mobil1 Synthetic Extended Performance 5w/30 and after about 3-5 days it is gone. I think the Mobil1 synthetics and other have detergent that help clean rings and such. But if it is so bad that you can hear it over the fan in the morning OUTSIDE the truck, I would say that is less than desirable.
I read that some people have good luck with higher visc oils (10w30, 30W, 20w50) etc. But only in warm weather would I go that high. I may get away with it because I am in south texas and it is over 90F most of the time. even gets over 100F for a month or so.
Good luck, and let us know how it works out!!!

PS I also bought a High Quality Mobil1 Oil Filter for $9.99 to match the quarts of oil I bought!! :)

It could be yourr air conditioning. When I was buying my truck and had it inspected I too noticed the clicking/knocking noise. I asked the mechanic what the clicking sound was and he told me that it was the air conditioner and that some are louder than others. perfectly normal tho.

Yeah, my truck "clunks" when the a/c compressor kicks on. First time I heard it, I was in a parking lot and I thought someone had bumped into me.

Wait... what year is your truck?

My truck is a 1999 with the 4.8 V8 engine.