Date:         Fri, 23 Jan 2004 00:41:40 -0500
Reply-To:     ROBERT DONALDS <donalds1@VERIZON.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         ROBERT DONALDS <donalds1@VERIZON.NET>
Subject:      Re: Cylinder hone -conclusion?
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Scott W. Fellow learkers and vanagon types

I measure and ridged hone new and used cylinders on a regular basis for both
the air and water-cooled engines. I use the very best bore micrometer money
can buy it measures in .0005th increments its fast and it shows a couple of
tenths taper with a sweep of the wrist it is in fact way cool if you like
that sort of stuff. I am often asked for one or more used cylinders to
replace the ones customer have dropped or damaged.
        I have been rebuilding engine for a few years and have seen what
happens when customers only replace the rings without honing the cylinders.
The short term problem is that the blowby otherwise know as crank case
pressure is severe because the rings do not seal. The long term problem is
that the rings wear out very quickly. So fast in fact you would think you
where gas washing the cylinders. This is due to the uneven cylinder surface
the ring both move up and down and in and out of the ring grooves. The
technical term for this action is called the hokey pokey.

    The cylinders on the WBX engines show little signs of wear even with
150K and with my ridged hone I can make them straight and round without
increasing the bore size by more than .001th I have not seen cylinders
become oval but they are never straight from top to bottom.
    I had a good laugh at the idea that the angle of the bore the piston is
in and gravity had an effect on the way a cylinder wears. The way a piston
moves in a cylinder is determined by the angle of the con rod pushing or
being pushed by the piston. Modern Pistons have an offset wrist pin hole in
the WBX piston the offset is .040th away from what's known as the load side
of the piston. The load side of a piston is the side that pushes against the
cylinder wall as the piston travels down in the bore on the power stroke
again this side loading is due to the angle of the con rod. The passengers
side of the engine has the load side of the piston facing up and the drivers
side would be facing down because of the clockwise rotation of the crank and
the angle of the rod. The reason for the offset piston pin is to transition
the piston from one side of the cylinder to the other as the piston reaches
the top of the cylinder and the piston reverses direction. Without this
offset you would hear a loud piston slap and that amount of noise gets old
very quickly. The engine would make more power without the offset but not
enough to make the noise worth listening to. Speaking of offsets the con
rods have an offset also but this is to make room for the cylinder beside
it. I have seen engine rebuilt by parts replacers with the con rods in
upside down this this has the affect of side loading the pistons. The small
end of the con rod inside the piston is rubbing against the piston pin boss
preventing it from centering in the cylinder and slowing down the transition
from non load side to load side of the piston just enough to make a the
noise of a slapping piston. this noise is allusive hard to diagnose and it
instills a complete lack of confidence in the engine. This lack of
confidence is well earned because the same guys that install the rods upside
down don't rebuild the big end of the rod and then he reused the same rod
bolts.

    The top piston ring land wear as Daryl mentions does determine the oil
consumption of an engine and in the old hotter running air-cooled engine the
ring lands did take a beating so reringing was a short term fix to a long
term problem. It is not that extreme with the WBX engine the oil consumption
is often low even up to the end of an engines useful days due to the lower
over all piston temps decreased ring land wear of the water cooled engine. I
always use new piston and cylinder sets because they make the best power
they offer the least amount of problems and its what the customer expects

    The days of deep lines in the cylinder walls to hold oil and lap in the
rings is ancient history. When I hone a new set of cylinders I start with a
220 grit stone and to remove the first .001th and straighten the cylinder.
Next I change  to a finer finish stone with a 150 grit this take's the tops
of the previous honing and adds about another 0005th with little effort. I
then use a full size scotch bright pad insert it in the cylinder and then I
spin it to remove any remaining high spots and clean the cylinders. The
reason I hone the new cylinder is for three reasons first I feel the piston
skirt to cylinder wall to tight at .001ths to .0015ths so I add .001th to
.0015ths next I like to see just how round the cylinder is by honing it and
third I want to reduce the plateau's of the original honing marks. All this
make for a faster brakein, lower friction and less chance of scuffing the
load side of the pistons in the first tring days of the engine life

    The rings on the market today are prelaped they are very round and
depending on how the heavy the honing is seal quickly. the exception to this
is the chrome top rings they are slow to brake in and depend on the carbon
particulate to lap into the cylinder. Chrome rings are not recommended for
alternative fuels such as propane and LNG these fuel burn to clean to offer
the needed carbon particulate.

    I have found that in the real world people don't bother chasing down a
hard to find straight 30 weight oil for brake in. This time of year in the
north its just to thick and the engine will spin but not let the engine
start so I feel that the 10 30 is a good brake in oil and I recommend that
the customer not drive on the highway for the first 1000 miles with this oil
because the engine is to tight the oil is to thin and the load would be to
high for a fresh engine.  The other thing I think is critical is to get the
engine set up with an exhaust gas analyzer. The 02 sensor does not tell the
whole story and is easily sooted up and put out of commission when starting
and running a fresh engine.

    The real problem that Scott will face in replacing parts rather than
rebuild the engine not restoring the proper dimensions and main bearing
crush. The main bearings will become loose in the case in a very short time
and he will have low oil pressure. he will again hear the often heard crank
grumble the 1.9 is famous for  this is true for all 1.9 engines. Throwing
new parts at an engine is no replacement for experience.
I have an article on alignboring the 1.9 cases check the archives I think I
called it tales of an engine stripper
if you can find it ask I will repost it

going faster miles an hour I remain
Bob Donalds
http://www.bostonengine.com
all right reserved

----- Original Message -----
From: "Scott W." <smorewhisky@YAHOO.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, January 22, 2004 5:57 PM
Subject: Re: Cylinder hone -conclusion?


> So are we all saying that if I was going to reuse
> these pistons and sleeves, that I would not want to
> hone the sleeves? Just clean everything up for
> re-assembly? My plan was to replace all the bearings,
> main,rod,crankshaft,camshaft. And to reuse the barrels
> and pistons. New heads. New pumps, oil and water. So
> assuming the barrels and pistons measure up ok, I
> could just reuse them without honing the sleeves? I
> guess that is the question.
>  thanks again.
> Scott w.
>
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