I've noticed something about my new truck. When it has been running awhile and I leave it idling for a period of time, it starts making a tapping sound that varies with rpm. Sounds like a bent pushrod or something. But, once I start driving it, the noise is gone. It also doesn't happen all the time, just when idling like thru a drivethru or waiting in line at the bank.

What does piston slap sound like? Is this what I am hearing? If so, that SUCKS.

1,600 miles on the truck right now.

Tony

 

I don't think it is piston slap. I think it is something to do with the fuel injection system, and is not damaging anything. My previous '99 5.3 and my '01 6.0 both make the same sound. Like you, I only notice it at a drive-thru or at idle, and it is random.

 

Vortec Tick, get use to it. I've heard lots of reasons. One I'm interested in is a fuel check valve. Daren said something about it. Heehee just wait till your fuel pump starts whinning, you won't notice the ticking anymore.

 

I get the same thing Tony.

Happens when the engine is cold or fully warm and been running for long periods of time. I couldn't quite narrow down the sound either. Sometimes it sounds just like exhaust, other times I swear I hear it coming from the lower half of the engine...that kinda scares me!

 

The piston slap seems to only be heard when you start up the truck... It knocks for a few minutes , then stops. I think that is why they call it a cold start knock..

Tony, I think Neil is right about thew noise you hear.. It`s the injectors.If you take you vortec plastic cover off and run the truck you may hear it a lot better.

( PS. I know you will take that cover off and add some Gankster graphics to it soon anyway).. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

I think that's injector or fuel system noise... like a noisy evap valve or something...

 

to; Fast 4.8,
My trk makes a whinning sound in 1st I
thought it was my torque-converter could
it be the fuel pump? it is very noticeable.
sounds allmost like tire spinning.

Jim

 

The fuel pump whine is most noticable at idle and usually whines after hot days , long drives or pulling loads. Your problem could be many things. Could be the tranny, or the rear end. Is your truck lowered? Does it only do it in 1st or during certain rpm ranges? Get as specific as you can and we will try to help you out.

BTW, start another topic since this is a different than the original topic. That way this topic won't get lost in the wrong place.

<small>[ March 20, 2002, 01:02 AM: Message edited by: Fast4.8 ]</small>

 

Tony, your motor is defective. Take it to MTI immediately for a 5.7l LS1 conversion w/ the stage 1 heads and a comp 216/220. Don't forget the normal bolt ons,etc... <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> Oh, Yank 3500 truck converter would top it off.

Hope this helps! <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

Thanks for the help Jason! I'm on my way over there now <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

*only* a 5.7L? <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Tony