Recently I brought my completely stock 02 WRX in for service because I was hearing a knocking noise coming from the engine on cold startup. The noise was intermittent and would go away after the engine was warmed up. I took the car in and the timing belt tensioner was replaced. The next morning I still had the same noise. So I left it at the dealer overnight and in the morning I met with the tech and the service manager to "listen" to the engine. I was told that the problem was piston slap, and that they werent going to do anything about it because it only did it when the engine was cold, and that this was "normal" for this engine. I personally thought this was a load of BS, so I called a Subaru specialist in my area and asked them about it. They confirmed my BS assumtion. Now I am stuck trying to contact SOA so I can get a new shortblock put in. Man I hate this crap. I love the car but have had nothing but hassels with it. I had it in 3 times because the dealership couldnt seem to find the leaky axel seal in the transmission even though I told them where it was leaking each time I brought it in. Not to mention the 4 days I had to wait so they could repaint the hood because the paint was peeling off. I am sick and tired of this crap. I hope that Subaru is going to stand behind their product and replace my engine. Feel free to post your comments. Happy Driving!!

 

The dealership was not willing to tear the motor down. I was told that it was piston slap, and it was normal. I just wanted some other input so I could figure out if they were really telling the truth.

 

The noise is not agressive, and only apparent at low rpm's at cold startup. The dealership told me that it was piston slap, which it could be, from what I hear the piston will expand when hot and when the engine is cold the clearance on one of the pistons could be a little on the loose side fo the tolerance. Then when the engine warms up the piston expands enough to get the clearance smaller. I was told by the dealership that if the noise persisted when the engine was warmed up that the short block would be replaced and that they would not tear down the block and replace the piston. From what I hear on i-club and clubWRX the noise is normal for subaru engines due to an expanding piston and the short skirt that they use on the pistons. The piston slap shouldnt cause any damage since it goes away after warm up, so looks like I will live with the noise as long as it doesnt get any worse.

 

Well last night I was out, and here in Denver the temp outside last night was around 35 degrees. When I started my car the knocking piston slap noise was about 10 times louder than it has previously been and now it will not go away even when the engine is warm. So I guess it is back to the dealership so they can replace the short block. I will post what happens when I call them tomorrow.