[Vwdiesel] 1.6TD compression numbers

[James Hansen]

ok, that makes sense. My tester seems to have a leak, I think at the quick
release. I
wonder how much this would affect the readings? I can hear it hissing when
the
cranking stops.
____

Quite a bit actually.  It's a relatively small space in the tester and hose,
so small losses add up pretty fast. Try to disassemble the female portion of
the connector and clean it, sometimes a speck of carbon gets in there, and
look at the o-ring. IF that's marked, it will leak.



Blowby is much more than it was just after rebuild, close to what my 300k km
NA
Jetta has at idle. Oil usage hard to tell for sure, but I do see blue smoke
for the first
5-10 minutes at cold start. None once warmed up.
The first trip was over Hwy2 from Seattle to Leavenworth, hard climb in 3rd
& 4th for
20 minutes, peak oil temps 265F. This after only about 400 kms of gentle
breakin.
Mostly hwy miles for another 1000 kms after that, with a few mtn passes,
then
another 1000 kms of gentle backroads. I've heard that overheating new rings
can
cause them to loose their 'spring'. I'm wondering if that's what I did... I
recall the
cranking on warm starts beginning while we were on that trip.

____
Overheating rings at any time will cause them to temper and lose their
tension.  At breakin, your best bet is to avoid the long hard runs, but go
flat out for a burst, till the rpm's get up to 3500-4000, let off, and let
the engine slow the vehicle.  Then floor it, repeat.  I do it ten times. The
gear doesn't matter so much, but not first, I like third, the runs are
longer.  You are alternatively heating the rings, and alllowing them to cool
and letting the oil wash the cuttings off the cylinder walls.  Yes,
cuttings.



I think I will try another compression test at some point. So you don't
think slower
cranking speed will affect numbers that much? I might try running two
batteries next
time just to see. But even after running the battery down, and cranking
another 20
secs or so to purge the air from the lines, it started and idled smooth with
no smoke
right after the test.
____

Well, cranking speed shouldn't matter so much depends what you call slow :-)
It did start so it couldn't have been that slow, but if you suspect the data
is wrong, it's cheaper to repeat the test than re-ring based on bad data. If
you suspect the tester was leaking, repeat the test with a different one.  I
could send you mine if need be.



If the hard breakin was to blame, then I will need to re-ring and do a
breakin around
town somehow, as any driving on trips is mostly fully loaded and dealing
with hilly
terrain.
____

Breakin for ring sealing is more like the first ten minutes of real driving
rather than the first trip.
That's to say, you seat the rings in the first ten minutes, but you seat
everything else that influences longevity over your first trip, so no fully
loaded trips up the coquihala for the first run, vary your speed, vary the
load, vary the rate of acceleration over the first day, but really pay
attention for the first ten minutes and do that right, no matter what.
That's the most important time really.

-James
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