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Piston slap
- Thread starter AdamXP800
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A link to piston slap explanation: http://www.pistonslap.com/whatisit.htm
My GMC pickup truck has had it for close to 300,000 miles, still going. Hope the link helps
My GMC pickup truck has had it for close to 300,000 miles, still going. Hope the link helps
Piston slap as I understand it is, the back and forth movement of the piston when moving laterally. Some piston slap is allowable, in fact normal, because there needs to be some space between the cylinder wall and the piston. Excessive piston slap is normally caused by wear of the cylinder walls and can be corrected by overboring the cylinders and using larger pistons.
Lou
Lou
Glad the info helped. No problem on the other.
Sportster-2001-951C-Stock
Well-Known Member
On some automobiles equipped with an air pump, the pump itself makes a sound that sounds just like piston slap.
I wonder if you could hear piston slap with the rest of the noise they make. It usually is cold and as soon as the engine warms up it is gone. The more wear the longer it takes, the colder it is the longer it takes for the engine to reach full operating temperature. It is a tapping noise, not a knock as in rod, that is the best I can do for a description at this time.
Sportster-2001-951C-Stock
Well-Known Member
Thanks for being more specific, any type of engine can have excessive piston slap and it just wasn't clear your Q was specific to a particular circumstance, or engine, or what your reason was specifically for asking when a simple WIKI search can answer this basic and general question.
I'm not sure you can distinguish it really, in a ROTAX XXX engine with compression of YYY, stroke of ZZZ, and bore of FFF with piston clearance of GGG, too much piston slap(clearance) results sometimes in cracks in the piston sleeve, and can result in piston overheating b/c the oil film on cylinder wall is responsible for conducting heat out of the piston, most of this heat occurs at the upper end of the piston where heat is absorbed from combustion. Excess heat leads to a breakdown of the oil film and aluminum meltdown, seizure.
The piston expands faster than the cylinder sleeve and is machined such that at temp a careful balance is achieved based on expansion rates, which is why it's not a good idea to abuse an 2-stroke engine by running overheated, running it hard before it's warmed up, or running for long periods at WOT. All IMO.
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68ragtop
Well-Known Member
The early GM LS1's where notorious for cold running piston slap. I had a 98 Trans am years ago, that I swore had bad wrist pins or rod bearings. sounded bad. GM said it was normal. It went away once it was warmed up. Followed that up with a 2000 T/A & that engine had none. When I sold the 98, the new owners went to the GM dealer before they bought it from me to confirm the sound was normal. (couldn't say I blamed them)
- BiRkS_
Active Member
Normally you can check piston slap by sticking a screw driver in from the RAVES (or wooden dowl) and push the piston back and forth. You should have no more than a few thousands of an inch of play. If you push it and it goes "clack" then you have excessive wear, either cylinders, piston, or stuck rings. You can also do it from the spark plug hole and push diagonally when the piston is at half its stroke. Worst piston slap i worked on was a golf cart. It would barely run, had 60 psi and i could literally stick a buisness card around the side of the piston and the bore. Now that was piston slap!
AdamXP800
Well-Known Member
WOW, stupid me... Only one of your genius would think to use WIKI. JK haha
Thanks for the information
jammin777
Well-Known Member
my 96 chevy k1500 5.7l is the same way sounds like a diesel untill it is fully warmed up and still running strong @ 262 k mi.
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