In article <9507241511.AA27368@nicmad.nicolet.com>,
gschneid@nicmad.nicolet.com (Gary Schneider) wrote:
> Thanks to Phil Willson for his thoughtful and helpful commentary!
A compliment at last! Thanks Gary, how much do I owe you?
> Phil or anyone have experience of engines running a long life despite
>start-up knock?
My 2.5 is up to 118,000 miles and has certainly knocked for the last 30,000
(since I bought it) but fitting and
anti-drain filter conversion reduced the 'oil-light-on' time considerably. As
Egil has said, ultimately the best
measure is oil pressure plus listening for knocking or or deep rumbling noises
during normal running. People do
worry about the Death Rattle too much, in my opinion, and the basic precautions
mentioned should be more than
adequate.
An Egil asked:
>And finally, to Phil: What would the size of the restriction be?
This is where opening one's big mouth gets one into trouble!! The simple
answer is "I don't know." In fact, I'm
not sure that the article/letter I read put a number to it and it would take me
hours, if not eons, to find it again.
However, I'm sure that one of the physicists or hydraulicists (is there such a
thing?) on the net could make a
suggestion based on fancy formulae. Taking the empirical approach
(i.e.guessing) how about observing the
rockers with the engine hot, with and without the basic oil feed kit. There
should be a noticeable difference in
the amount of oil oozing out of them. Then put in a restriction of say 1mm and
again observe the effect. If one
of the people who observed a measurable pressure drop were to try this, then
they could observe whether the
original pressure could be more or less recovered AND an improved flow to the
rockers could be seen.
In order to do calculations you would have to know what the pressure is at the
feedpoint in the head to ensure
that there is a positive pressure gradient i.e. that oil will be fed to the
rocker system and not taken out!
Over to the fluids people. I can only deal with electrons and things although,
of course, there are parallels
between hydraulics and electricity (pressure=voltage, flow=current,
restriction=resistance etc.). But I've never
stood in a puddle of electrons. Oil, yes!!!
Phil
From: Phil Willson
Electronic Engineering
Queen Mary and Westfield College
London E1 4NS
Tel +44 (0)171 975 5338
Fax +44 (0)181 981 0259
email p.j.willson@qmw.ac.uk
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