Great... I Now Have Piston Slap!

Jet-X · July 29, 2003

Well, with a little over 12K miles I now have the infamous piston slap syndrome, on my 5.3. I knew it was a matter of time, but I didn't think it would happen this soon. Oh well.....

1BADHD · July 29, 2003

Just drive it like you stole it. Keep the carbon build up to a minimum and you'll be fine.

gmcjoe · July 29, 2003

Well, with a little over 12K miles I now have the infamous piston slap syndrome, on my 5.3. I knew it was a matter of time, but I didn't think it would happen this soon. Oh well.....

The 'piston-slap' condition does not appear IMO. Either it is there or it isn't.

My 2000 GMC has had it from day one and after 89K miles, no problems

ugeesta · July 30, 2003

My 02 has 'slap' in the morning for the first 30 seconds or so. With only 2,800 miles on it, I'm going to try teh 'drive it like you stole it' idea to keep the carbon build up down. Also, I noticed (with my 01 5.3) that the higher octain gas you use, the less knock your engine has.

2001 HD · July 30, 2003

Well at least get it to the dealer and have it documented and insist they give you a free powertrain warranty if you don't already have one.

Mine hasen't gotten any worse @ 37K. After Chevron Techron Fuel Sytem Cleaner and oil changes it doesn't last as long. Sometimes in cooler weather, it doesn't do it at all???

Haven't heard of any failures.

The SPEEDY · July 30, 2003

Oh well.....

Yep, you either have it or you don't, just one of those things.

Like 2001 HD said, take it to the dealer and have it documented.

SilveradoWV · July 30, 2003

Haven't heard of any failures.

jek2424 · July 30, 2003

i have a 02 2500hd with 6.0 L, it has the"slap"and have warranty, and i have started using 93 octane gas and full synthetic castrol 5w-30 it has helped out a bunch with the so-called "normal noise" that gm calls it. a mechanic told me to start running straight 30w oil and it would help, but i don't know whether to try that or not? any id eas? but who can afford using 93 octane and full synthetic oil?

bigtruck21 · July 31, 2003

don't use 30 weight unless you want to lose mileage and startability in the cold. 93 octaine will also net you less mpg. Use the lowest octaine w/o pinging. The 93 suggestion was made based on the idea that the 93 octaine might contain more/better "cleaning" additives than the lower grade gas, but I haven't tested it for sure. I'd run 87 and use a throttlebody cleaner/fuel treat every so often/ or make longer driving trips to keep the carbon from building up.

staged455 · July 31, 2003

93 octane will not hurt your mileage. It has always helped my trucks with mileage as it allows the pcm to keep the timing fully advanced. Put a scanner on your truck and drive it sometime while watching timing advance. It will also prevent detonation which would be a bad thing if the truck already has piston slap. I've always ran 93 octane and synthetic Mobil 1 when I was driving gas burner GM trucks and Suburbans. I use my trucks for pulling horse trailers and my racecar trailer and 93 makes a big difference on a hot day when pulling the trailer in hilly areas. It completely eliminates detonation except for the 100 degree days. Both of my last 2 350 equipped 4X4 Suburbans had over 200,000 miles when I got rid of them and both got over 18 mpg on the highway with the 350 and 373 gears. I decided I needed more power and stepped up to a diesel and I've never regretted that move.

bigtruck21 · August 4, 2003

Maybe not for your vehicle with it's towing situation, but for mine without towing and 75%hwy 25%city it did. 93 octaine gave avg 14.9mpg...91 octaine 15.7mpg...89 oct 16.6mpg....87 oct 17.3mpg. All are averages making sure the tank of gas was "pure." Time of year was fall with temps in the 50s and 60s. With yours and it's pinging, it would only make sense it wouldn't apply. Notice I said, lowest without pinging. Many people have found my situation to be the same.