[Vwdiesel] Re-ring for low compression

[Val Christian]

I had several 1.5 which were in similar condition, and I did the fast
re-ring job, coupled with cleaning or rebuilding the head.  I've always
had the head shaved just a little, even though VW says it shouldn't be
done.

On a 79, which had 140K, when I bought it, had been re-rung.  I did it
again at 290K, and the car was retired at 335K.  At that time, compression
was waning, and sometimes variable.  Generally it needed encouragement
for starts below 0F.  But I ran heavy oil back then.  Encouragement meant
a propane torch on the oil pan, and a jump for the start.
This car had character.  It also had the rocket rabbit oil sucking
power attacks.  Complete with full effort braking, with the inability to
stall the engine.  Clouds of smoke and all.  The only direct consequence
was that marginal glow plugs didn't survive.  This car also had
dripping injectors, which took out glow plugs as well.  The T-hose
fix never really worked.  Oh, the eccentricity of the bore was the
greatest on this car, over 0.1mm.

On a 78, which I owned from day 1, it got a re-ring and head job when the
cylinger head gasket went at 220K.  The original cyl head gasket leaked
a little from day one.  One day it just failed.  The car made it to beyond
380K, after the floorpan just got too ventilated after patching a couple
of times.

On an 84, which I bought with 80K, the head was done once at 110K, and
the rings were replaced.  The cylinders were not too far out of round.
The car was retired in the high 200's...I don't have it written in my
folder for that car.

Right now I have a 92 Jetta (1.6), which I've had since new.  220K.  Always
used gasoline engine oil in it.  Compression 350/380/320/360 at 180K.
Never had the head off.  It has a mysterious coolant leak, after a
thermostat failure (the rivet holding on the circ valve plate failed).

Back to the point, the first three examples are of engines where a quick
re-ring job was done.  I've always roughed up the cyl walls, using
a straight stone.  I've heard that the broom-type hones may be easier to
get a nice finish with.  On the 78 and 79, the wear was less than .15mm,
however, on both of those engines the piston skirts had moderate or
worse wear.  On the 78, I roughed up the skirt with a prick punch, and
then leveled the high spots with a file and emery paper.  On the 79,
I replaced a bad pin.  Back in those days I ran 20W50 in the summer
and 10W40 in the winter.  In each case, I got much more than 30K.  Actually,
of all the engines I've done a quick re-ring on, I can't think of any
dying with less than 50K.

Perhaps this will be encouragement for someone contemplating a re-ring.
My luck has been good, but your mileage may vary.

Val


Forwarded message:
>
> Ken,
> I would say it depends on how much money you want to spend.
>
> If it is bad as you say, then a re-bore and new pistons are in order.
> However...
>
> On my first diesel rabbit, before I knew any better, I replaced the
> rings in a 1.5 that was in worse shape than you describe. It ran great
> for another 50K miles before I sold it. I just hand honed it to dress
> the cylinders for the new rings.
>
> I think these engines tolerate greater tolerances than specified. But
> that's just me.
>
> -Gary, Orlando
>
>
>
> On Sun, 2003-01-26 at 15:07, Kenneth E. Oldrid wrote:
> > I have a question regarding my 86 jetta 1.6 NA, 250k. The engine just stopped
> > working last fall, would not start. Compression test yeilded following values
> > in psi: 220, 350, 150, 240. I believe all values are supposed to be around 395
> > give or take 20%. So I removed the head, which looks great by the way, and
> > measured the bore of 2 cylinders, and they were out of round by .1mm, more than
> > the allowed .03mm. I'm wondering what my options are to bring it back to life.
> > How much would a machine shop charge to bore out a block? I would have to buy
> > oversized pistons and rings for this, correct? Could I get away with installing
> > new rings without replacing pistons or boring out the block? WHat do you guys
> > do in this situation? Everything else on the engine seems to be fine.
> > thanks,
> > Ken
> > _______________________________________________
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> > vwdiesel at vwfans.com
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>
>
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