Piston Slap Options?

andyrud · December 8, 2009

My 2000 Silverado 5.3L Engine has had piston slap for the last 6 years. I know I have to live with it but I was wondering if I should be using any special oil or doing anything to help my engine last longer? Is the piston slap shortening my engines life?

Thanks in advance,

Andy

bluesrefugee · December 8, 2009

My 2000 Silverado 5.3L Engine has had piston slap for the last 6 years. I know I have to live with it but I was wondering if I should be using any special oil or doing anything to help my engine last longer? Is the piston slap shortening my engines life?

Thanks in advance,

Andy

If you haven't done anything by now, I would say that the damage, if any exists, has already been done after 6 years. Synthetic oil couldn't hurt. Maybe one of the high mileage varieties.

c4cruiser · December 8, 2009

My 99 Silverado with the 5.3 motor had piston slap for nearly 7 years when I traded it last year with 77K on the odometer. All I ever did was to change the oil every 3K miles. I had always used dino 5W-30 in it and for the most part I used Chevron that we have at the shop. Never had a problem with power, oil consumption or even smoke at startup.

I wouldn't worry about it.

zaac · December 9, 2009

My 2000 Silverado 5.3L Engine has had piston slap for the last 6 years. I know I have to live with it but I was wondering if I should be using any special oil or doing anything to help my engine last longer? Is the piston slap shortening my engines life?

Thanks in advance,

Andy

Same truck here. I've used dino and synthetic, 5-30 and 10-30. The piston slap doesn't change. My truck uses a litre of oil every 10k kilometers and runs nice so I'm not worried about it. Just wait until it quits rattling before driving.

ColoradoSkiCountry · December 9, 2009

Had Piston Slap on my 99 5.3. Synthetic 5W30 did quiet it down slightly but it was still there. I've had it since day 1 on my 07 5.3L as well, and am currently using regular dyno-oil. Did try it with Synthetic 5W30 on my 2nd oil change, did not quiet it down. It only lasts for 2-3 seconds after start-up and goes away. No worries, your engine will be fine and last you till you sell it.

Scott02Z71 · December 9, 2009

My 2000 Silverado 5.3L Engine has had piston slap for the last 6 years. I know I have to live with it but I was wondering if I should be using any special oil or doing anything to help my engine last longer? Is the piston slap shortening my engines life?

Thanks in advance,

Andy

I have a 02 5.3 that also has had piston slap since day 1. I have 169,000 miles on mine and it has no problems. I change my oil every 3-5k with Mobil 1 Syn. Drive it till it puts all 4 in the air...

pistonslap · December 10, 2009

My 2000 Silverado 5.3L Engine has had piston slap for the last 6 years. I know I have to live with it but I was wondering if I should be using any special oil or doing anything to help my engine last longer? Is the piston slap shortening my engines life?

Thanks in advance,

Andy

How many miles/kilometers ? Does it use any oil between oil changes?

gmcsierra93 · December 10, 2009

Throw some Lucas at it and trade it off.

ken1mod · December 10, 2009

Gentlemen,

Do you want your engine to have the correct tolerances/clearances for the first 30 seconds of running. or the next 8 hours of work?

Cold tolerances are transitional. After 30 second clearances are what counts.

ken

VMax2007 · December 10, 2009

Gentlemen,

Do you want your engine to have the correct tolerances/clearances for the first 30 seconds of running. or the next 8 hours of work?

Cold tolerances are transitional. After 30 second clearances are what counts.

ken

If GM had smart engineers, they would be able to eliminate thermal expansion. Hell, it's only physics after all.

kdixer · December 10, 2009

Gentlemen,

Do you want your engine to have the correct tolerances/clearances for the first 30 seconds of running. or the next 8 hours of work?

Cold tolerances are transitional. After 30 second clearances are what counts.

ken

My 02' Avalanche had piston slap from the time I bought it @ 48k miles until I traded @ 118k miles. It was not just at start up. It slapped anytime it was sitting there idling. Piston slap is not from a tolerance that is temperature dependant. It is from the piston pin being off center.

I would dare say that most start up ticks and pecks are from the hydraulic lifters.

VMax2007 · December 10, 2009

Gentlemen,

Do you want your engine to have the correct tolerances/clearances for the first 30 seconds of running. or the next 8 hours of work?

Cold tolerances are transitional. After 30 second clearances are what counts.

ken

My 02' Avalanche had piston slap from the time I bought it @ 48k miles until I traded @ 118k miles. It was not just at start up. It slapped anytime it was sitting there idling. Piston slap is not from a tolerance that is temperature dependant. It is from the piston pin being off center.

I would dare say that most start up ticks and pecks are from the hydraulic lifters.

It's a combination of many things. Tolerances to allow for thermal expansion are one of them.

kdixer · December 10, 2009

Gentlemen,

Do you want your engine to have the correct tolerances/clearances for the first 30 seconds of running. or the next 8 hours of work?

Cold tolerances are transitional. After 30 second clearances are what counts.

ken

My 02' Avalanche had piston slap from the time I bought it @ 48k miles until I traded @ 118k miles. It was not just at start up. It slapped anytime it was sitting there idling. Piston slap is not from a tolerance that is temperature dependant. It is from the piston pin being off center.

I would dare say that most start up ticks and pecks are from the hydraulic lifters.

It's a combination of many things. Tolerances to allow for thermal expansion are one of them.

Which tolerances cause piston slap?

Piston slap is from the piston rocking clockwise and counter clockwise as it travels up and down the cylinder. That is from the piston pin being off center. No piston fits tight enough to the cylinder wall to not slap. And the centerline of the piston is the same no matter how hot or cold it is.

dlstewart01 · December 10, 2009

Gentlemen,

Do you want your engine to have the correct tolerances/clearances for the first 30 seconds of running. or the next 8 hours of work?

Cold tolerances are transitional. After 30 second clearances are what counts.

ken

My 02' Avalanche had piston slap from the time I bought it @ 48k miles until I traded @ 118k miles. It was not just at start up. It slapped anytime it was sitting there idling. Piston slap is not from a tolerance that is temperature dependant. It is from the piston pin being off center.

I would dare say that most start up ticks and pecks are from the hydraulic lifters.

It's a combination of many things. Tolerances to allow for thermal expansion are one of them.

Which tolerances cause piston slap?

Piston slap is from the piston rocking clockwise and counter clockwise as it travels up and down the cylinder. That is from the piston pin being off center. No piston fits tight enough to the cylinder wall to not slap. And the centerline of the piston is the same no matter how hot or cold it is.

Then why doesn't my truck slap, knock, or tick. It never has on start up or running......

piston slap occurs when the clearance between the piston and the cylinder bore is too great. The piston to cylinder bore clearance becomes too great either through wear, mismatched pistons and cylinder bores at manufacturing or, a combination of both. The audible noise associated with excessive piston slap is due to the perpendicular impact of the piston against the wall of the cylinder bore. Audible piston slap is typically loudest when the engine is first started up. The pistons then expand with heat reducing the piston to cylinder bore clearance thus, reducing the perpendicular impact of the piston against the cylinder wall and its resulting noise.

In the case of the famous GM piston slap engine defect, the piston design with hypereutectic (high silicon content aluminum alloy) pistons, reduced or eliminated piston skirts (to reduce reciprocating mass), and a higher ring pack to reduce unburned fuel mixture on the sides of the piston crown have made piston to cylinder bore fit much more critical. The amount of tolerance (variation or margin) in allowable clearance between the piston and cylinder bore to prevent audible piston slap has been reduced by a factor of at least 50%. Consistently hitting the narrower margin for piston to cylinder bore tolerance has not happened for GM during mass production. Thus, some engines have no audible piston slap and some have piston slap on only one or two cylinders.

VMax2007 · December 10, 2009

Which tolerances cause piston slap?

Piston slap is from the piston rocking clockwise and counter clockwise as it travels up and down the cylinder. That is from the piston pin being off center. No piston fits tight enough to the cylinder wall to not slap. And the centerline of the piston is the same no matter how hot or cold it is.

Pistons "rock" due to the change in force direction at TDC/BDC. Offsetting the wrist pin is designed to minimize this rocking. It does not cause it. The piston does not "rock as it travels", it only rocks at the instant the force vector changes direction at TDC and BDC.

If you take a cross-section perpendicular to the piston axis in the area of the skirts, it is NOT perfectly round. It is purposely designed slightly elliptical to accomodate the different amount of material mass in the skirts. After thermal expansion, the piston becomes perfectly round.