[71chevydude]

I have a noise on the restart of a warm 4.8 engine on my 2003 silverado. I have changed the oil at 2500 5000 and 8000 mileswith mobil 1 synthetic, the truck now has 8000 miles on it and the noise started after the last oil change. there is no noise on cold engine start and the noise isnt too loud when stopping and idling for a short time with a warm engine, then slowly it gets louder.It gets really bad when you let it sit for 10 to30 minutes and then start it. The sound is most noisy for the first 10 seconds or so then slightly quieter.If you rev it up slightly 2 or 3 times then let it idle the noise stops for about 5 to 10 seconds then starts up again. I have read about the O-ring on the oil pickup tube being bad on some engines with similiar symptoms as mine. Ive read one complaint exactly like mine but he did not have a solution. GM is going to change the O-ring, Im not totally convinced this will cure it. any answers would be appreciated, other than that problem I love my truck.

 

[Stocklook]

Did it work, my 02 does the same thing the dealer said there is no fix but GM gave me a 100k 7yr warranty on the eng.

 

[jebx]

Did it work, my 02 does the same thing the dealer said there is no fix but GM gave me a 100k 7yr warranty on the eng.

I think you are talking about piston slap, his issue isn;t because it makes noise on warm startup.

My question is was it doing this before you lat changed the oil? If no, it sounds like the check valve on the oil filter is sticking. I'd spend the $3 on a new filter to just eliminate that.

 

[Stocklook]

The tapping is all the time after warm up for the last 20k miles hot days it is worse it seems to be coming from the top of eng (valves) when the rpm's go up the tapping goes away, but GM claims this is normal

 

[Big D]

i also have the 100k warranty. i have other issues which u can read abt in other threads, but i also just had a torque converter replaced under warranty trying to cure another problem and all my noise is gone. when u let off the gas, does it also have this faint tapping noise as it decelerates? i am so happy that my noise is fixed, but i aint telling them, cause i got the 100k.

 

[BDZ71]

i also have the 100k warranty. i have other issues which u can read abt in other threads, but i also just had a torque converter replaced under warranty trying to cure another problem and all my noise is gone. when u let off the gas, does it also have this faint tapping noise as it decelerates? i am so happy that my noise is fixed, but i aint telling them, cause i got the 100k.

Mark, What kind of noise and when was it making it? Thats awesome that the TQ fixed it.

 

[Big D]

it was a tapping noise on warm restarts.....mine was so loud it sounded like a diesel. i shit u not. it was exactly like what this dude is having. i have heard loose t/c bolts b4 and it generally sounds tinny. this doesnt at all. it sounds just like piston slap or valve clatter.mine made the noise on warm or lukewarm start ups. u could hear mine from in the house and it did progressively get louder as months went on. i got the 100k so i was waiting for it to blow up..lol. i still have very minute amt on first start of day which i aint worried abt but i am so happy the other is resolved. this guys just sounds the same. couldnt hurt to check

 

[Whifflebat]

it was a tapping noise on warm restarts.....mine was so loud it sounded like a diesel. i shit u not.

:word: I've heard it, he/we shit you not.

 

[Blue02]

My truck knocks all the time gm says it's piston slap i say thanks for the 100k engine warranty. cant wait until 99k new engine for me j/k

 

[BDZ71]

My truck knocks all the time gm says it's piston slap i say thanks for the 100k engine warranty. cant wait until 99k new engine for me j/k

Really? Seems to be a 4.8 trend :insane: Kind of strange. Wonder if it is like BigD? Might want to take it back and ask them to check?

 

[jebx]

My truck knocks all the time gm says it's piston slap i say thanks for the 100k engine warranty. cant wait until 99k new engine for me j/k

Piston slap should NOT cause knocking all the time. What causes it is a short piston skirt and high tolerances causing the piston to be able to move(slap) around in the cylinder. Once it warms up a little it will not knock because the tolerance had decreased (the piston heated and expanded). If it is knocking all the time take it back, something else is wrong.

Info - Engine Knock on Cold Start #01-06-01-028
Engine Knock on Cold Start

4.8L, 5.3L or 6.0L Engine (VINs V,T,U - RPOs LR4, LM7, LQ4)
Some of the above vehicles may exhibit an engine knock noise that begins in the first
19,000-24,000 km (12,000-15,000 mi) of use The knock noise is most often noticed
during initial start-up and typically disappears within the first 5-30 seconds (may last
longer in extreme cold temperatures). The noise is usually more noticeable on the initial
start-up when the temperature is below 10 degrees C (50 degrees F) and may be more
pronounced on the first cold start following a long trip.
This noise may be caused by an interaction between carbon that has formed on the piston,
the piston motion and the cylinder wall. GM Powertrain Engineering, and an analysis of
engines with this condition, has confirmed that the noise is not detrimental to the
performance, reliability or durability of the engine. THIS NOISE DOES NOT HAVE
ANY EFFECT ON THE LONGEVITY OF ANY OF THE ENGINE COMPONENTS.
Important
At this time, attempts to repair this condition by replacing the engine assembly or pistons
is not recommended.
Please share the information found in this bulletin with customers who inquire about this
condition. In the event they have additional questions orconcerns, please advise your
Area Service Manager.

 

[Blue02]

Mine makes the same annoying sound all the time. I will eventually take it in but they are just going to tell me the same thing ohh it's piston slap heres a printout about it bla bla bla. I will just have to wait until something breaks

 

[jebx]

Go somewhere else, it should NOT make noise all the time. I have 0 noise with my 4.8 unless it is cold, and even then it is faint.

 

[Stocklook]

GM sings the same song and dance that the noise is normal I have e-mailed GM with a two page letter stating that my engine makes a tapping noise all the time and is worse on hot days, they called my dealer and I'm going to take it in on sat. the service adviser said it is not normal for it to be all the time it sounds like something else (OK who is right!) But you guy's know GM they will say now, that my cold air intake and exaust sys has voided my warranty and causing the engine to tap. just to get out of replacing or fixing the engine.

thanks to all of you, the advise has helped

 

[jebx]

GM sings the same song and dance that the noise is normal I have e-mailed GM with a two page letter stating that my engine makes a tapping noise all the time and is worse on hot days, they called my dealer and I'm going to take it in on sat. the service adviser said it is not normal for it to be all the time it sounds like something else (OK who is right!) But you guy's know GM they will say now, that my cold air intake and exaust sys has voided my warranty and causing the engine to tap. just to get out of replacing or fixing the engine.

thanks to all of you, the advise has helped

Under the magnamusson moss act they have to prove that the aftermarket part caused the issue for it to void the warranty.

 

[Big D]

shit get under there urself and check the tq bolts.....if they r loose, take it to gm and say " fix it fuckers! " mine knocked all the time and that is what it was. i was so glad to tell courtesy chevy to blow me. everytime i went there, nobody ever checked it. they came onto the drive......listened......and said the same thing.

 

[Stocklook]

Well I went to the Dealer today to get insp and talk to them about the tapping noise they told me nobody was there to look at it and told me the blah blah blah crap this time it was carbon build up in the cylinders and offered to clean it for me for a PRICE $$$$$$$ They also offered to sale me a new 2004 truck ext cab for the same payments 0 down
what to do ? any feed back would be great! how are the 04's the int is Kinda blah