I have a 99 obw. Bought it in may. Never had any noises that may be piston slap. Just did headgaskets about a month ago. Ran super quiet for a subaru. Lately, I'm getting a tap cold. Lasts about ten min. Not loud but annoying. Noise just suddenly appeared! I know both y pipe gaskets have minor leaks. I remember sbc motors with header leaks that sounded just like a valve tap. They would also go away when the engine warmed and expanded. Any chance oem gaskets might quiet it down, or is this the infamous subaru piston slap? Just seemed to happen suddenly. Colder weather maybe?

Manifold gaskets are about $10, I think.

Cheap and fairly easy to find out if that's it.

yeah do the exhaust gaskets now before the rust/bolts get any worse!

When I did the hg, I replaced all the studs and nuts. Used fel pro gaskets though.

When I did the hg, I replaced all the studs and nuts. Used fel pro gaskets though.

 

 

eek! felpro head gaskets?

 

Piston slap goes away after 5 minutes or so. A leaky exhaust may do that too as the parts heat up and close the gap.

I think he meant the exhaust gaskets were felpro. Those should be fine, but the mating surface of the pipes and heads need to be cleaned and completely free of rust, old gasket material, and carbon buildup, before installing new gaskets or they may leak.

 

Piston slap is more of a low thunk or clunk sound.

I got oem gaskets. Cleaned both the heads and flanges real well. Sprayed gaskets with copper sealer. Then I took off the last heat shield by the oil filter, and wrapped the y pipe in header wrap. Amazingly quiet! It really helped as the fel pro gaskets were leaking bad. I still have a rapping noise at start up. It goes away after 5 or 10 min. I know the only fix for slap is to replace the piston but is there anything else I can do to quiet it down? I'm using an 0 w40 now. Little thicker oil maybe?

I got oem gaskets. Cleaned both the heads and flanges real well. Sprayed gaskets with copper sealer. Then I took off the last heat shield by the oil filter, and wrapped the y pipe in header wrap. Amazingly quiet! It really helped as the fel pro gaskets were leaking bad. I still have a rapping noise at start up. It goes away after 5 or 10 min. I know the only fix for slap is to replace the piston but is there anything else I can do to quiet it down? I'm using an 0 w40 now. Little thicker oil maybe?

 

 

Basically turn up the stereo. It is annoying but nothing really to worry about, there are quite a few engines out there (hello old GM) that do it far worse.