Change the tappets
Question : I DRIVE a 1998 Proton Wira
1.3 (automatic) that has clocked 160,000km. The engine makes a loud clattering
noise as soon as the vehicle comes to a halt. My mechanic reckons that the
hydraulic tappets require replacing and the cost is fairly substantial. Please
confirm my mechanic's diagnosis, as I do not want to spend any unnecessary
Answer : WORN hydraulic tappets probably cause the clattering noise
that your engine makes, so your mechanic's diagnosis is probably correct.
Tappets are designed to keep a small clearance between the valve stem and the
cam lobe of the camshaft. The clearance ensures that the valves land quietly on
their seats. The clattering noise that you hear is the sound of valves landing
heavily on their seats.
Hydraulic tappets fail when they begin leaking or if the fine oil channels _
within are blocked with debris. Although one may attempt to clear any blockage
by soaking them in paint thinners and then blowing through with
compressed air, this is usually futile and
further noise means removing the cylinder head again at a later stage.
The tappets should be replaced as an entire set since the failure of any
single tappet would mean the remaining ones could be on their way out.