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Piston Clatter

I have a 2003 Subaru Forester XS, bought it new, has almost 100,000 miles. Only take it to the dealer. Regular oil changes, and routine maintenance. Around 65-70,000 miles, I began to hear a sound like a playing card against a bicycle wheel in colder temps only. Dealer called it ‘piston clatter’ and not to worry about it. So I didn’t. Over the years it has become a year around sound, even worse in colder temps. I’ve been afraid to drive it out of town on the interstate or highways because at times the engine sounds as if it’s going to jump out of the car. I wrote to Subaru corporate, only to be referred back to the dealer, who again, will only tell me it’s ‘piston clatter’. I have used fuel additives, and a tank of premium every now and then. Still makes the same sound. Any other owners out there who have experienced the same thing with their Subarus?

I think its more commonly referred to as piston slap, and some Subaru’s have been known for it. Piston slap is when the side skirts of the piston slap against the cylinder walls. This usually only happens when the engine is cold, and should stop after engine is warmed up. If after the engine warms up, and its still chattering while going highway speed could indicate a more serious problem.

I would get a second opinion from a mechanic other than at the dealership…

+1 for Caddyman.

Does this rattle occur with the engine idling and the car not moving?

Thanks everyone for your comments. Americar, it used to only happen when the car was cold, then stop when warmed up. Now it does it year around. I never hear it at highway speeds.

Caddyman, I am planning on having a second opinion by a mechanic, not the dealer.

ok4450, it makes the sound all the time except when going downhill and my foot is not on the accelerator.