Piston Slap

Hey Guys!

I just stumbled on to this post by accident, but like to tell my story. I’ve been driving GM trucks since the early 80’s and the noise you are talking about started when they went to aluminum heads. You have dissimilar metals heating up at different rates, and that is what causes the valve clatter you are hearing! I have a “01” Yukon
with 398,467 miles on it, it has made that noise from day one.
 
The reason my 07 GMC Sierra was making a lifter noise was cause the engine was not receiving oil. i changed the oil pump and still the noise was there with the pressure going down to 0 when it was idleing the red oil light would come on and say to shut engine off.
im getting a 09 engine swap today lets see how it turns out.

-Rowdy
 
piston clearance

I have heard that this is caused during assembly they use too select pistons by measuring the clearance in the cylinder, now they just put pistons in some too tight some too lose and the ones that are lose are the ones causing piston slap.

it cut down on production cost saving time by skipping this measuring each piston to cylinders.

i have heard this from a friend that had this pistion slap in he V-6 that was new in his gm car.
 
I own a 2001 gmc 4.8 and a 2000 chevy 5.3. My 4.8 has made this slap and a noise that only can described and a diesel like sound for more then 200,000 miles. while the 5.3 has no sound at ALL. GMC has told me for 10 years that there was nothing wrong with the 4.8, that all the motors did it. NOT TRUE! Only some of them do it. But in all this time I have put that 4.8 through h@!! only to have the tranni go out twice and the rear diff once. And the whole time it was running on 92+ octane gas and a HyproIII programmer! So the carbon build up is BS!!! That motor is spotless in side....
 
sea foam the slap

Just bought a 02 gmc 5.3l with 200,000kms(120,000mi)had the knock real bad on 1 cyl only,would last up to 5 min. Truck had fresh pensoil in it 5w-30 dino oil.Have used sea foam in my bikes so tried it on truck, 1 full bottle in intake manafold and then put in 5w-30 synthetic oil. Noise is now a light tick and is gone after few min ,not sure if was sea foam,oil or both. Hope it lasts.
Z15 said:
Carbon buildup in the engine can cause anywhere from a ticking sound similar to a lifter to a rather loud knocking noise similar to a main bearing knock. The piston hits the carbon accumulation in the combustion chamber and makes the sound, which is often misdiagnosed as piston slap. Because the carbon swells up upon engine cool down, the noise will be more prevalent on start-up following prolonged downtime.

This is usually the result of lower quality lower detergent gasoline being used over many miles.

If an engine had piston slap is would occur from day 1 and not come on after many thousands of miles. Often top end cleaners will help clean out the engine but you have to be careful using them to prevent engine damage. There is one popular product many use but the name slips me. Sea Foam is the cleaner, many claim it eliminates the noise if only not for just a short time because people go back to buying the lower cost and lower detergent fuels instead of the Top Tier. Google top tier gasoline
Click to expand...
 
if the oil pressure is still regular and not bouncing around then it might be ok, but my truck would make the slap and oil pressure would fall to 0 with a message saying turn engine off.

had to swap motors, got a 09 engine in my sierra now. and it runs clean. hopefully it doesnt come back at 90,000mi.
 
Happy 2011 I agree...

My 02 has 186,000 plus on it, it has piston slap but the engine is VERY strong. I just maintenance it and it keeps running like a champ. (It helps to have a very good mechanic who I have taken my outfits to for over 10 years).

Now if I could get someone to chime in on my question about the "Ride Control" option on my truck...
 
I have returned with the answer to my problem with my piston slap (2001GMC 4.8 liter V-8 truck.
Starting in cold weather was the problem, the solution found a warmer climate, no more slapping noise at start up.
As far as the cold weather start up, the solution was found by speaking with my Doctor. He recommends, turning on the radio after starting, let run between 45seconds to 1 min. and 15 seconds, and the piston would be corrected and run as required.
I still have the the truck and it still runs great.

Happy motoring.
Rogerj
 
I have an 02 2500 HD with the 8.1 and it's made that noise forever. I had a friend buy an 02 with the smaller V8 and his made the same noise. I let it run for 20-30 seconds and the noise goes away. Oil pressure is normal according to the gauge. I have no faith in our local dealer so I never took it in. My truck only has 89,000 miles now since it sits a lot during the summer months, but it runs fine.
 
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