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The subject of Piston Slap...
DOCUMENTATION BY INDUSTRY EXPERTS ON THE SUBJECT OF PISTON SLAP:
Dr. Victor Wong/MIT (Massachusetts Institute of Technology), is
one expert who states otherwise:
Piston Slap. Few technologies have received more engineering
attention than the internal combustion engine. Yet engine
designers continue to be troubled by a phenomenon known as
"piston slap." As a piston moves up and down inside its cylinder
it also shifts from side to side, bumping first one side and
then the other--a behavior that wastes fuel, wears out engines
and makes an annoying bang. A computer model developed by MIT
researchers can disentangle the factors that lead to piston
slap, helping engineers make design decisions that will reduce
its intensity. Given a description of the operating conditions
and design of an engine, the model can describe the pathway the
piston follows inside the cylinder, the force with which it hits
the wall, and even how its shape changes due to the impact. In
parallel work, the researchers have validated the model using an
operating experimental engine. The team was led by Dr. Victor
Wong, a principal research scientist at MIT lecturer in the
Department of Mechanical Engineering. The work was funded by
Nissan Motor Company. reference:
http://web.mit.edu/newsoffice/rd/1996/sep.html
Bob
Hagin/Syndicated Columnist/ Seattle Times disagrees with GM’s
rational on piston slap:
The noise called piston slap is caused by one or more pistons
having too much clearance between its side skirt and the
cylinder walls. In effect, the pistons become too small and
wobble in the cylinder bores. It can be cause by an engine
simply wearing out (not common any more), a piston seizing
because of a lack of lubrication (it runs out of oil) or it's
put together wrong. This is easy to check and usually it doesn't
happen to all the pistons. But there could be other causes, none
of which could be caused by a "wrong" oil filter. Find out what
brand oil filter your shop uses and call its service reps and
tell them your story.
reference:
NWclassifieds/Autos- Research It: Auto Q&A
James E. Harris, proprietor of Engine Restorations in Portland,
Maine also disagrees with GM’s assertions regarding piston slap:
One way to check for piston slap: Remove three spark plugs,
leaving number one in place. Crank the engine over until you
feel the resistance of number one piston coming up on
compression. Crank against compression until the piston is about
half way up the cylinder. Now using the fan, rock the crankshaft
back and forth and listen for a metallic knocking sound. If you
hear a knock, you have piston slap and the only way out is to
rebuild the engine.
reference:
http://www.forengines.com/enginetips.html
Piston slap is not
"nothing to worry about."
http://cartalk.cars.com/content/columns/Archive/1994/September/07.html
Cosworth
Performance –
http://www.algonet.se/~cossie/FAQ.HTM
Jaguar World Magazine –
http://www.jagweb.com/jagworld/xk-engine/page5.html
Western Filter Company –
http://www.westernfilterco.com/4_ring_piston.html
Australian Energy News
http://www.isr.gov.au/resources/netenergy/aen/aen12/12yoke.html
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