03 Baja Knock

[Johnson]

Is it unusual for the 4 cyl to knock loudly when first started?
I have noticed that the Baja is louder than it used to be when first
started. It has about 25000 miles on it.

 

[jMon54]

I have about 37k on mine and all I can tell you is there is a bit less
noise overall when I use synthetic oil. Mine is garage parked at home
which might help with starting easier.

 

[Edward Hayes]

I have the same engine in my 2000 Forester and with 102,000 miles it
doesn't knock at startup. Are you using the correct oil viscosity.
Maybe a defective oil filter? I very light piston slap is noticeable
just before I tap the accelerator about 5 seconds after the engine
starts.

 

[Johnson]

Dealer has changed the oil since new.

I have the same engine in my 2000 Forester and with 102,000 miles it
doesn't knock at startup. Are you using the correct oil viscosity. Maybe a
defective oil filter? I very light piston slap is noticeable just before I
tap the accelerator about 5 seconds after the engine starts.

 

[Voja Ilic]

Welcome to the club. Mine OB 02 knocks since 25K KM on cold days (below
5C ~ 35F). They changed engine short block and that helped for about 10-20K
KM but it's back again. The reason is very simple, pistons are wider then
longer so until the engine warms up they hit the cylinder walls and makes
knocking sound. They (Subaru) thought if they strip pistons of exces weigh
they can reduce emissions and increase power. The drawback is engine knock.

Cheers,
Voja