Chapter 59 PowerPoint

Define these Technical Terms using the textbook:

1. camshaft positioning tool

2. chain tensioner

3. engine front cover

4. engine front seal

5. timing belt

6. timing belt cover

7. timing belt tension

8. timing chains

9. timing gears

10. timing marks

Answer these discussion questions using the textbook:

1. How do you check a timing chain for wear?

Read the chapter summary below:

■ Timing chain wear can allow the camshaft to go out of time with the crankshaft, reducing engine power and increase emissions.

■ To check timing chain tension, rotate the camshaft sprocket back and forth and measure the distance the sprocket turns before the crankshaft begins to turn. You can also measure the maximum deflection of the chain and compare it to specifications.

■ Timing chain tension on an OHV engine can be checked by turning the crankshaft back and forth and checking for valvetrain movement. If the crankshaft can be turned excessively without valvetrain movement, the chain is worn and loose.

■ Timing sprockets with plastic gear teeth are prone to wear and failure.

■ A bad chain tensioner can cause excess chain slack.

■ When installing a timing chain, align timing marks on the crankshaft sprocket and camshaft sprocket. Sometimes, a key way or dowel is used as a timing mark.

■ Do not hammer on the outer edges of sprockets to force them into place. Use light blows in the center of the sprockets.

■ An oil slinger fits in front of the crankshaft sprocket to prevent oil leakage and to lubricate the timing chain or gears. Make sure it is not installed backward.

■ Replace the crankshaft oil seal whenever it is leaking or the front cover is removed. The front seal can be replaced in the vehicle with only partial engine disassembly.

■ When installing a new front oil seal, coat the outside diameter of the new seal with non-hardening sealer and wipe engine oil on the rubber sealing lip. Drive the new seal in squarely.

■ An engine front cover can be installed using a conventional gasket, chemical sealants, or both. Use anaerobic sealer to seal two thick or solid pieces, and RTV or silicone sealer where a flexible part mates with the front cover.

■ When installing a vibration damper, make sure the damper seats squarely on the crankshaft snout. If it becomes misaligned during assembly, stop and align the damper to prevent part damage.