In article <3B15E97E.63B4C12D@zianet.com>, Michael D. Porter
<mporter@zianet.com> writes
>
>
>Michael Hargreave Mawson wrote:
>>
>> Carly's latest trick is blowing pale blue smoke. :-(
>There has been some suggestion, on the lists, and in other places
>(namely, lubrication-related sites), that thicker oil may actually
>exacerbate the problem, rather than cure it.
>
>At any rate, 15W-40, for normal summer temperatures, is quite adequate.
Thanks for confirming that.
>
>To amplify upon the problem of oil smoke, two things should be checked.
>First, in what mode of operation the smoke occurs matters. If it is
>present at low engine speeds and large throttle openings, one may
>rightly suspect rings. If it occurs at high engine speeds, say, over
>4000 rpm, or is more pronounced when closing the throttle quickly at
>higher engine speeds, then the likely culprit is large valve
>guide-to-valve stem clearance.
Since I'm running in at the moment, taking the engine over 4000 rpm is
something I have avoided. The blue smoke is visible, but not too bad,
at lower revs, but is quite appalling when the throttle is "blipped"
(i.e. sudden downward pressure on the accelerator pedal, taking revs up
beyond 3500, then immediately released) particularly when there is no
load on the engine. From your guidelines above I conclude that I have
both ring *and* valve trouble. Am I right?
>
>In any case, the second thing to be checked, before embarking upon a
>bottom-end rebuild, is compression, using dry and wet tests. If the
>compression is lower than about 20-25% of normal, the engine probably
>needs a rebuild. If the wet test compression readings are 15-20% higher,
>or more, than the dry tests, ring replacement is probably in order. If
>there's no dramatic difference between the wet and dry tests, but
>compression is still on the low side, valve work should be on the
>agenda.
This seems excellent advice; many thanks.
ATB
--
Mike
Michael Hargreave Mawson, author of "Eyewitness in the Crimea"
http://www.greenhillbooks.com/booksheets/eyewitness_in_the_crimea.html
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