Fixing Piston Slap
5 Year Member
Joined: Feb 2016
Posts: 1,033
Likes: 253
From: Florida
OP'er,
are you sure its piston slap you're hearing?
Piston slap typically quiets down just a little when the engine is at operating temperature.
Thats due to the cylinder, piston and rings expanding with heat.
Could also be other things like a cracked flex plate, rod knock, crank end play, worn timing chain, bad lifter, something knocking against the frame, etc.
You might want to stethoscope the noise to verify.
are you sure its piston slap you're hearing?
Piston slap typically quiets down just a little when the engine is at operating temperature.
Thats due to the cylinder, piston and rings expanding with heat.
Could also be other things like a cracked flex plate, rod knock, crank end play, worn timing chain, bad lifter, something knocking against the frame, etc.
You might want to stethoscope the noise to verify.
5 Year Member
Joined: Feb 2012
Posts: 13,851
Likes: 2,739
I had a 79 LTD wagon, and the original 5.0 had piston slap. Sure enough around 55K miles it departed with prejudice while going 25 MPH uphill. Made it to my driveway with a hole in the block. I got a JY 5.0, cracked it open and found the pistons were chaffed from piston slap in it as well. So had the block bored, honed, and piston matched, then went to town on the block opening oil passages, smoothing the block, heads, matching intake and exhaust ports, pretty much as blue print as it can get, then put 300K on the engine in two different cars.