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.
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.