I had a few guys tell me i have pistons slap.... what exactly is it?

 

Mechanical noise from pistons rocking in their bores a little (usually noticeable only when cold).
Not an unusual condition, and not usually anything to worry about.
-Rich-

 

common and not a problem in engines with forg4ed pistons due to the excessive clearance when cold, after the piston expands the "problem" goes away.

 

my car was warm, i had been driving it for about 2 hours, and i was sitting in a parking lot with it in park, just talking ot some people, and it died, and would not restart for like 15 minutes.... it would start to turn over then stop, like it was locked up or something... then when we got it started, when you would rev it a lil and then let off the gas, the engine would make a bad noise and i asked, "whats that" and they said piston slap.... so that is the storry, what are your thoughts?

 

doesn't sound like piston slap to me

 

Sounds more like an terminal internal problem. Could be anything.

You're probably going to have to pull the engine apart to see what's wrong. Pull the valve covers and if possible, pull the oil pan to check it out first.

 

I am planning on pulling the engine anyways, and rebuilding it,,,, i guess now is as good a time as ever

 

theres no way to tell whats wrong man
it could be a million things you wont know for sure untill u take it apart

not tryin to hijack anythitng here but my mom has a 2001 silverado with the 4.8....when its cold the pistons slap for a little bit maybe 15 seconds.....ok then 2 hours after driving city and hi way it comes back...the same noise...

my dad took it to a gm dealer and told them to fix it...they said it was piston slap and that theres no need to fix it.. to which my dad replied ok so why does it do after 2 hours of driving sitting there idleing...

apparently gm knows about this and continues to aloow this to happen....what could be wrong

ohhh they also extended the warranty on the powertrain untill 100,000 miles because they dont want to fix it

 

For what it's worth, my EdelBrock carb owner's manual (in the back) states that the fuel is boiling under the "hard starting" symptoms. But about the only reason it would boil is because you have steal tubing ran from your fuel pump to the carb.

I had this problem before I got an EdelBrock and fixxed it by insulating the metal fuel line. ~After my truck was nice and toasty you couldn't touch the fuel line.

 

 

Actually I had a similar fuel boiling thing going on for a while once..... the car would drive around and run just fine it seemed, although it smelled alot like gas after it had been running for a half hour or so, and seemed like the gas consumption went WAY up if I drove it around town for an afternoon or something; and if I stopped and went inside a store for like 5 minutes, then came back out, it would be hard to start and idle terrible; then as soon as I tried to take off into traffic, it would go about 50 feet and die, and take forever to start back up, and blow out vast clouds of black smoke.

Turned out, I had got in a hurry when putting the fuel pump on, and didn't use a gasket, only some silicone. The pump was getting hot and heating up the fuel, which after a good heat soak, would flash into vapor by the gallon when it got to the carb. Put gaskets in it, instantly took care of it.

But I doubt that has anything to do with a bottom end mechanical noise.

 

yeah where did any of this fuel boiling problem come from, did someone post on the wrong topic? I am confused

 

He said he still has the problem of it stopping when warm and not cranking for 15 minutes


What else would stop it from cranking warm?

 

A fuel issue won't keep it from cranking, but it may keep it from starting.

 

Sounds to me like a worn wrist pin on a rod. Wrist pins dont just give way, they get worn from excessive blow by, which would show up in the pvc, and your oil will get dirty immediately.
Once the wrist pin is worn, the sympton will be a hard to turn over motor, especially when it is warm.

 

LOL, cranking, starting, funny how I meld those two together.

Piston slapping from short piston skirts or because the rings are broken in a little to well? I can see that making a little noise but not that much. About the same noise as non-hydrolic lifters?

Now saying the timing chain is worn is a much better explanation in my mind. But my mind sucks, I can't even figure out how to swipe my check card at Wal-Mart

 

I know what you mean, i have hte same swiping problem at walmart, their damn machines are fubard