Bad lash adjusters sound like this (MP3
- 159Kb) - video of
same noise (WMV - 488Kb). It's the loud tapping noise.
Here are some notes and pictures regarding the replacement of the valve lash
adjusters on a 1990 Subaru Legacy. Starting off:
Remove the battery.
Unbolt the two bolts holding the washer bottle in place, disconnect the
pump connector and move the bottle out of the way.
Disconnect the three engine connectors and the single bolt holding the
wire holder in place. The transmission filter must also be removed from
the body of the car. It does not have to be disconnected, just lowered
to get it out of the way. Remove the three bolts holding the valve cover
in place. With the valve cover removed, the rocker assembly can be seen.
Valve
cover removed: 
There are 8 bolts holding the rocker assembly in place and must be loosed
over a couple passes in the correct order. In the center of the rocker
assembly are four bolts. The upper left is 1, lower right is 2, upper
right is 3, and lower left is 4. The far upper left is 5, far lower right
is 6, far upper right is 7, and far lower left is 8. I attempted to label
them in the above picture. The rocker assembly can now be removed. The
SOHC can be seen.
The rocker assembly removed. It is important to keep the assembly
clean and lubricated. I placed the assembly on an oil container and poured
clean oil over it after removing any dirt.
The lash adjusters can now be removed. I used a pair of needle nose
pliers to pull them out.
New lash adjusted can now be installed. The adjusters must first
be bled of any air. To to this, I took a small container and filled it
with oil. Then each lash adjuster was placed into the oil container and
while pushing on the bottom ball spring (which seals in the oil), the plunger
is pushed over and over (about 12 times to be sure) until all the air is removed. With
the adjuster still in the oil, release the ball spring. When the lash
adjuster is removed from the oil, the plunger should be very hard. I
used a small allen wrench to push in the ball spring. Before installing
the lash adjusters back into the rocker assembly, I filled the rocker assembly
holes with clean oil.
The rocker assembly can now be installed back onto the head. The
tightening order should be followed. When placing the rocker assembly
back on the head, I used a couple of the bolts at the outer edge (#7 for example)
to loosely hold the assembly onto the dowel pins before I starting to tighten
the remaining bolts.
The valve cover can now be installed.
The transmission filter can now be clamped back onto the body of the car.
The washer bottle, associated connector, and the engine wires can now be
reattached.
The battery can now be re-installed.
Now the engine sounds good again! MP3 (163Kb),
and video of
the same (WMV 547Kb).
Update 02/23/2003
After driving for a couple days, the problem came back. It
turns out that one of the oil holes was clogged despite blowing them
out with air. I found it necessary to dig out the dirt using a
needle or something similar.
