Group 21
Checks and adjustments
93
Camshaft
Camshaft and valve tappets, checking
Using a steel ruler (
1
), make sure that the contact
surface between the valve tappets and the
camshaft is convex or level. If the surface is
concave, replace the valve tappets.
If the valve tappet is worn across the lifting
surface, the tappet should be disposed of. ”The
ditch” shows that the tappet has not rotated.
A dark stripe farthest out on the lifting surface,
however, shows that the surface is not worn.
The condition of the valve tappets determines
whether the camshaft should be checked for wear
or not.
Make sure that the lifting surfaces on the
camshaft and the valve tappets do not have great
pitting damage. Pitting damage can appear for
different reasons. The damage consists of small
metal pieces being broken off the hardened
surface. Tappets and camshaft with minor pitting
damages can be used. Pitting damages are rarely
worsened.
Make sure that the bearing race and cam curves
of the camshaft are not abnormally worn. For
example the camshaft lifters may be obliquely
worn axially. This can, in mild cases, be adjusted
by honing.
If there are greater damages and wear, replace
the camshaft.
NOTE!
If the camshaft is replaced, all valve tappets
must also be replaced.
Special tools:
Dial gauge ................................................... 998 9876
Fitting tool, camshaft bearings .................... 999 8695
