Valve noise Geo Metro

Answer 1

The Geo Metro holds a small volume of oil (4.5 qts) and suffers when down a quart. So maintain oil level is the first solution with some timing adjustment. As well, Increased valve chatter with age is normal, but the in the example of 1.3L 4 cylinder the hydraulic rocker arms (valve lifter, and valve lash adjuster((partsdinousaur.com cheap by experience))) the rollers may break.

The roller of the rocker arm is held by a shear pin that may fail. Remove the valve cover (careful not to over-torque when reinstalling((4ft*lbs)), it will break cover!) and the Spark plugs (compression) and rotate the crank shaft the camshaft will rotate with the crank giving play to the rockers. Being careful not to damage the polish surface you can check that the rollers move freely.

(((( Or ))))

For easier inspection, you can remove the valve cover (careful not to over-torque when reinstalling((4ft*lbs)), it will break cover!) Then unbolt the "Rocker hold down bars" (Two, exhaust and Intake 5 bolts each 25 ft*lbs) and inspect the rollers but finesse is required in reinstalling with weak springs and washers that can fly off in different directions

Also inspect the hydraulic lifters (valve lash adjuster, kind of like a bullet) in the end of the rocker do see if it is dead and does not hold oil with resistance. these can be checked in place and pulled out with pliers (warning may destroy) ((the lash adjuster is a valve with a ball bearing on a spring with a can on the other end that always bleeds pressure. at higher rpm and oil pressure the can is held firmer and further open thereby opening the valves further. if replace remember to prime with oil))

(((Secondly)))

The Piston skirt shattering will cause a "valve chatter noise".

To inspect drain oil, remove oil pan take care with crank position sensor bolt and torques (aluminum plus steel bolts equals stripped threads) . with flash light check piston skirts from underneath. inspect oil pans for the piston rings (unmistakeable) If broken, the piston can be replaced with more difficulty, but if you took off the oil pan it is not impossible. a gently used 88mm piston suzuki 13BBA can be found in a junk yard for fifteen bucks (done on two separate occasions and have two spares) and a imperfect installation without honing and crosshatch surfacing can be accomplished to get you back on the road with little detriment.

And If into perfection a new oil pump to pick-up oil pressure and make the lash adjusters solid to minimize the gap may do the trick.

AND remember to verify your torque specs (Haynes Manual or Chilton)