Interference and Timing

1
Interference and Timing

• Object To distinguish between interference and
  non-interference engines, as well as emphasize
  the importance of timing belts.

2
What is a Timing Belt?

• Timing/Gilmer/Cam belt is part of an internal
  combustion engine.
• Material rubber
• Purpose control timing of engines valves
• Some engines use gears or chains instead.

3
What does a timing belt do?

• Turns the camshaft at exactly 1/2 the speed of
  the crankshaft
• Maintains a precise alignment. 
• This means that the crankshaft will make two
  revolutions for every revolution of the
  camshaft. 
• The camshaft causes valves to open and close in
  time with the pistons which move up and down in
  the cylinders. 
• The valves must open and close in precise timing
  in order for the engine to work

4
Breaking and Replacing

• Must be replaced every 96,000 km to 168,000 km
• Must be replaced if there is any damage like
  cracks, cuts or excessive wear
• When it breaks, camshaft stops turning leaving
  some of the valves in the open position. The
  crankshaft continues to rotate by inertia.
• The engine will stall, leaving you stranded.

5
Interference vs Non Interference

• Interference engine pistons will strike the
  valves that are left open resulting in broken or
  bent valves, damaged pistons, and possibly,
  destroyed cylinder head.
• The damage will be less extensive in a
  non-interference engine
• http//en.wikipedia.org/wiki/Timing_belt