pistons moving side to side wtf???

[180ways2slide]

i recently pulled my motor out the car. it is a built sr with cp pistons and eagle rods .020 over, i had no problems but the motor has running strong for 2 years and i put about 7k miles on it. so i pull the head off and the upper oil pan to check everything and everything looks good but i notice when cleaning th e top of the pistons they had slight movement side to side. is this because of the bore or is there something i need to look out for???? thanks

[91rps13]

piston slap. yeah its probably because of worn out cylinder walls or incorrect bore.

[Def]

How slight is "slight?" The larger piston to wall clearances of forged pistons will give you a very small amount(maybe a few thousandths) of movement when cold. That's what gives you the piston slap sound when cold.

Does it go away when they get hot?

[180ways2slide]

yes it goes away after it is warm and it is very little movement and the walls are clean too no real marks. So u guys think it's nothing to worry about

[Def]

It's almost surely fine if the piston slap goes away when warm.

[180ways2slide]

i know the slap goes away cause i dont hear it after a while but i want to no while the motor is out and the head is off should i be able to move the piston with my hands, can my motor be bored incorrectly or what about my rings?? btw the runs good and does not smoke at all just wanted to check it out cause its been 2 years

[jakerps13]

Seated rings and pistons will have some movement.

You can easily measure it by sticking a feeler gauge between the cylinder bore and piston. Start small and go bigger until it doesn't fit and there's your rough clearance. Or take it somewhere and use a dial bore gauge to also check taper and out of round.

Piston ring gap can be checked easily but you'll have to pull the pistons out and take off the rings. If you're going through all this trouble though, I'd get it checked out, rehone, and put back together with new rings if everything measures out.

BTW, forged pistons will make some noise when cold.

[silviakid2790]

that is normal.. especially in a bored engine...

[5150Fab]

a buddy of mine has a built wrx. cp pistons...very noisy when cold. its probably nothing to worry about. aluminum takes a slightly longer time to heat which in turn expands the pistons to the proper fit in the cylinders. have you always had the noise when cold or did it recently start to happen. If recent, probably a good idea to double check tolerences while dissassembled.

[TUnity2]

well if it's been runnign great for the last 7k miles then i would think it's normal.

[180ways2slide]

yeah it's always made a noise when cold and I run her on 20psi with no problems. Another quick ?? Should I replace anything while the upper pan is off?? She only has about 7k on her and it's not dd, just curious

[Mr.GT30]

it normal. for piston to move side2 side just a little bit beacuse all piston forge or OEM will need a slide clearance some where about .030 to .040 base on the piston clearance specification due to expansion from heat. so don't worry .

[180ways2slide]

thanks for everyone clearing that up for me. I guess I'll put everything back together and stop worrying