64
Repair Instructions
Lifters and camshaft,
inspecting
Inspecting valve lifter
Check with a steel ruler that the valve lifter contact
surface to the camshaft is spherical (convex). It may
also be flat but never concave. If light is visible in the
center of the lifter surface between ruler and lifter the
lifter should be replaced.
NOTE! If the lifter is worn across the lift surface the
lifter should be discarded. The “trench” indicates that
the lifter is not rotated. A dark line along the edge of
the lifter area indicates that the surface is not worn.
Investigate why the lifter has not rotated before in-
stalling the new lifter.
Small pitting damage on the valve lifter and cam-
shaft.
Check lifter surfaces for pitting damage. Pitting dam-
age can occur for different reasons. The damage oc-
curs by small metal particles being loosened from the
hardened surface. Valve lifters and camshafts with
minor pitting can be reinstalled.
It has been found that the damage seldom gets
worse.
Check the camshaft bearing caps and cam lobes for
wear. Cams can be unevenly worn axially.
This can be adjusted in minor cases by grinding the
cams. Replace the camshaft in cases of further dam-
age or wear.
All valve lifter must be replaced when replacing
the camshaft.
Camshaft, measuring
Measuring the camshaft
Measure the camshaft bearing caps with a micro-
meter. Maximum wear 0.05 mm and oval 0.010 mm.
The shaft out-of-true (straightness) is checked by in-
dication. Maximum radial runout relative to end bear-
ing 0.08 mm.
The lift height is measured with calipers as illustrated
above.
Lift height C = A – B.
For measurement details for camshaft and camshaft
bearings, see “Technical data”.
Содержание 300 Series
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Страница 96: ...7741725 1 English 10 2001 ...