Thanks Marshall......
John Ervine and I have been volleying about the term.......
Take care,
Chuck
On Mar 9, 2006, at 2:30 PM, Marshall Booth wrote:
Chuck Landenberger wrote:
Marshall,
I know I am being "teutonic" as I write this, but I'm going to send
it anyway.
IMHO, there is no such thing as timing chain "stretch". Rather, it
is an elongation of the timing chain spacing due to wear, allowing
for a "slop" (technical term) to effect engine/IP operation.
Chuck, Not sure who instituted the term "stretch" in referring to
chain
wear (the chain DOES get longer), but that's the term that is
routinely
used to describe timing chain wear (or perhaps the measure of that
wear)
and the unit of measure that's routinely used is "degrees of stretch"
which is the retardation of cam timing with respect to crank position.
As a first approximation, injection pump timing error in Mercedes
OM61x
and 60x diesels is ABOUT 1/2 what cam timing error is (I've
estimated it
- never measured it). In OM61x diesels about 5 degrees of cam error is
usually considered the limit of chain life while the chain in an OM60x
diesel should be replaced when the error exceeds 4 degrees. Chains
seldom break until the "stretch" exceeds about 8-9 degrees (the
pistons
and valves can collide at about 10 degrees) but once stretch reaches
about 4 or 5 degrees, wear seems to increase rapidly.
Marshall
--
Marshall Booth (who doesn't respond to unsigned questions)
"der Dieseling Doktor" [EMAIL PROTECTED]
'87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87
190D 2.5
turbo 237kmi
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