|
The camshaft is driven by the
crankshaft by one of three methods:
- Gear drive
- Sprockets and timing chain
- Sprockets and timing belt
Camshaft parts. Courtesy of
Ford Motor Corporation.
- Check the camshaft for:
- a plugged oil feed,
- the correct cam lift or
- any broken or severely
worn areas.
- Check each lobe and journal
for:
- scoring,
- scuffing,
- fractured surface,
- pitting,
- and signs of abnormal
wear.
Steel camshaft and roller
followers in good condition.
Badly burned and worn
camshaft bearing bores.
Normal lobe wear is a pattern
slightly off center with a wider wear pattern at the
nose than at the heel. The off-center wear is a
result of the slight taper of the lobe used in
conjunction with the convex shape of the lifter to
rotate the lifter.
Normal wear patterns are
slightly off center on the lobe. Reprinted with the
permission of Ford Motor Company.
- If the wear pattern extends
to the edges of the lobe, the lifter will not
rotate.
- If there is any scoring or
galling, the camshaft will have to be replaced
or reconditioned.
Premature lobe and lifter wear
is generally caused by metal-to-metal contact
between the cam lobe and lifter bottom due to
inadequate lubrication. The nose will be worn from
the cam lobes, and the lifter bottoms will be worn
to a concave shape or may be worn completely away.
This type of failure usually
begins within the first few minutes of operation. It
is the result of insufficient lubrication.
|
