I have a 95 subaru, auto wirth 109Kmiles.  I'm getting sounds from the passenger side of the engine which could be piston slap but which sound different.

 

This car has hydraulic valve lifters.  So is there any point on taking off the valve cover?  I couldn't check the valve clearance could I, since they adjust every time I drive the car.  The sound is much louder on acceleration and quites slightly when hot.  It's in sinc with the RPM of course.

Pull the valve covers and see if you can tell anything.

HLA's can seize in a position, leaving room for issues.

 

A stethoscope might help narrow down if it's in the front or rear cylinder on that side.

 

A compression test might tell you something as well.

 

The passengers side VC is rather easy to remove, unless they're relatively new it's worth considering if this is a good time to just replace the VCG's since they always leak at some point. It's so common I would suspect they've had to be replaced already.

Edited July 14, 20178 yr by idosubaru

A oil+filter change sometimes works wonders.

Also worth checking the spark-plugs.

Could be 'pinging' from one cylinder.

Any CELs? (1995? Not OBD yet?)

Edited July 14, 20178 yr by forester2002s

dose it get quieter or louder with rpm increase?

 

you might have a weak TB tensioner, that may allow the belt to make a knocking noise.

mikec - how's the car?

Edited December 12, 20178 yr by 1 Lucky Texan

bump