Piston slap is pretty easy to diagnose in its early stages.
You will hear piston slap most prominently when the engine is dead
cold and under a load, and it will diminish as the engine warms up.
Is this what the OP was experiencing?
Hard to say. This engine, if I am interpreting it correctly,
should be a 2.2 litre SOHC H4 boxer arrangement.
I have been curious about these for a long time, but have no
experience with Subaru. They are supposed to be good strong
I'd like to hear any comments about this setup.
i experienced this for years with honda engines, and was particularly
disappointed when my new 2000 civic started doing it after only 30k miles.
but recently, i tried an oversize oil filter on a high mileage civic
because the motor was particularly noisy, because i figured there was
nothing to lose from better oil flow. i was stunned at the result -
"piston slap" almost entirely gone when cold. looking back on the 2000
civic, the noise started round about the same time i transitioned to the
new smaller honda filter pattern - it would have been interesting to see
what would have happened if i'd gone back to the old size honda filter.
since the old noisy civic discovery, i've tried this on my accord too
- same noisy "cold slap" went away using a larger filter.
bottom line, these new smaller "more efficient" filters may be fine in
terms of performance when the oil is at full working temperature, but i
believe their cold flow characteristics are inferior and restrict flow.
it follows that the noise we're therefore hearing is actually
bearings, not pistons.
i don't know if a larger filter [with larger medium area and thus less
cold flow restriction] is available for subaru, but if it is, for <$7,
it's worth trying. for honda, wix #51344 does the job nicely.
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