4 – VALVE TRAIN
57
Piston Engine Fundamentals
TC010-05-01S
Chain Adjuster
Timing chain tension changes with engine temperature and wear. A chain
adjuster mounted on the cylinder block uses both engine oil pressure and
spring tension to automatically maintain timing chain tension.
When the engine is started, oil pressure builds in the adjuster. As shown in
Figure 40, oil pressure and spring tension push the chain adjuster sleeve
outward if the chain is loose. The ratchet pawl skips to the next tooth,
pushing the chain lever against the chain, taking out excess slack. When
the engine is stopped, the oil pressure drops, but the ratchet pawl prevents
the adjuster sleeve from being pushed back into the chain adjuster.
FIGURE 40. The
chain adjuster
uses oil
pressure and
spring tension to
automatically
maintain timing
chain tension.
Ratchet
spring
Ratchet pawl
Chain aduster
sleeve
Drain
Plunger
spring
Chain lever
Timing chain