URQ quirqiness Compression testing

[cobram at juno.com]

You're mixing tests up.  The TDC valves closed is associated with a leak
down test, NOT a compression test.  A leak down test involves compressed
air from an external source and measures the rate at which it bleeds out
the cylinder, and hopefully a diagnostic as to which path excessive air
leakdown is taking.  This is done with a static engine.  A compression
test is done with a spinning engine to compare values to the rest of the
cylinders, and to factory specs, both high and low.  

BCNU,
http://www.geocities.com/cobramsri/
There are two types of tragedies in life. One is not getting what you
want, the other is getting it.


 SuffolkD at aol.com writes:

> quattro-request at audifans.com writes:
> 
> Won't just testing all 4, 5, 6 or 8 cylinders as the motor sits 
> leave some 
> valves open?
> 
> Don't you have to turn the engine over to TDC or some position where 
> the 
> cylinder being checked has both valves closed?  Hence screwing in 
> the compression 
> tester in the last hole:  the spark plug?
> -Scott by BOSTON
> > 
> > 
> > > Pull the compression gauge out and to my horror #4 & 5  don't 
> > > even bounce the gauge. NOTHING!
> > 
> > Although I am not really offering much of a solution, such bizarre 
> 
> > measurement results prompt me to suggest rechecking, just in case 
> 
> > something about the test setup was awry.