Eric,
That is an interesting thought, but It brings up some other questions. Why
would the compression increase with the number of revolutions? I thought
the amount of compression was decided by how much pressure the rings and
valves could hold. If this is true then the pressure should build up and
stop at a certain point period. The other question is why does it need to
be more than one revolutions? Shouldn't one revolution give you the same
results? Each revolution the valves open and release the pressure. I do see
a jump in pressure and then as the engine turns it builds up higher. Is
this because of the exhaust stroke compared to the compression stroke of
the engine? Does the engine temperature make a difference on the
compression readings?
Thanks for the information and maybe you can answer some these additional
questions.
Ron Olds
At 01:27 PM 12/18/97 EST, you wrote:
>On Sun, 14 Dec 1997 20:13:07 -0600 you said:
>>Is there any specific way to do a compresion test. I have a tester but am
>>curious if there are any special tips that I should be aware of before
>>using it. After taking a reading is it advisable to squirt some oil into
>>the cylinder to see if there is any changer in the reading? Any advise
>>would be appreciated.
>>
>>Thanks,
>>
>>Ron Olds
>>50 TD
>>72 TR6
>>
>
>Ron, at a recent Tech Session I attended, I was suprised to hear that the
>common wisdom of the group was to check the reading of the guage at the
>third crank-over of the engine, even though continuing to crank the engine
>will produce higher readings.
>
>The reasoning behind this method is that a "good" engine will produce "good"
>readings by the third crank, but a not-so-good engine may produce "good"
>readings if cranked long enough.
>
>I had never heard this before, and my method and experience is that I got
>the highest readings after 6 or more cranks.
>
>I'd be interested in hearing what others on the list think about this.
>
>Of course, the usual warning about keeping the intake throttle plates
>wide open during the test, bears repeating.
>
>Eric
>
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