Damaged or worn ring lands, (piston groove walls) can cause the leakage
and inconsistent compression reading you are getting. Now you also know
the value of the leak down test I promote. Saves a lot trouble shooting
time.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
David Kao
Sent: Saturday, June 16, 2007 11:14 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Is this the cause of my engine compression problem?

Bob:

I did the pressure test at TDC. The leak is obvious comparing to the
cylinders
that do not leak.

I now wonder why a few times I got 150-160 PSI compression out of cylinder
#1.
The compresstion test I did after re-torguing the head nuts cold engine
got
all 4 cylinders at 150 PSI or better. This is inconsistent to what I found
today. It's back to exactly right after I completed assembling the engine,
#1 and #3 around 90-100 PSI but #2 and # at 150.

Driving around the block it's not bad. But when it needs some power to
climb
a small hill it just lacks the energy reasonably expected. My 84' with a
tired
engine does better. This is why I know something is not right with the
rebuilt
83' engine.

Now that I kind of know what the problem is I will just take a break then
attack it again when I regain energy to drop it and take it apart again.

If I need invidual cylinder/piston I will buy from you. Thanks for
mentioning
it.

David

--- Bob Donalds <donalds1@verizon.net> wrote:

> The leak down test should be done at TDC for the cylinder to be tested
>
> I use cofap but I do inspect and remove the taper from the cylinders. If
the
> cylinder is the problem its scuffed due to overheating or the pin clip
did
> not stay in the groove
> I have good used pistons and cylinders if someone feels the need
> This is what I use on my own vans. I fluff and buff them in the Boston
Bob
> style
> The cofaps are a good option and the feed back I get is positive when it
> come to power
>
>
> B Bob
>
>
>
> ----- Original Message -----
> From: "David Kao" <dtkao0205@YAHOO.COM>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Saturday, June 16, 2007 4:49 PM
> Subject: Re: Is this the cause of my engine compression problem?
>
>
> > This is to keep everyone posted. I found the real problem eventually
by
> > doing
> > a pressure test to the engine.
> >
> > I borrowed a compressor and coverted my compression tester into an
adapter
> > for
> > pressure testing the engine. Found excessive leak in my #1 cylinder
> > through the
> > piston rings into the crank case. I could feel a strong flow or air
coming
> > out
> > of the blowby breather hose, which has an opening inside the S shaped
> > intake
> > rubber bellow. I could feel a strong flow of air flowing from the
crank
> > case
> > through the hose into the bellow. It pushed my finger out when I tried
to
> > block
> > it off.
> >
> > Ouch..... It's a new liner there!!! How will it leak like that? When I
did
> > the
> > same to cylinder #2 the pressure was only at 20 PSI and it pushed down
the
> > piston
> > and caught me by surprise. It could not push the #1 piston even at 50
PSI.
> > I had
> > transmission in 1st gear and parking brake on with wooden blocks in
front
> > of the
> > front wheels. So the van did not try to run away but the tail of the
van
> > sank a
> > few inches. There was no obvious air flow through the blowby breather
hose
> > when
> > testing cylinder #2.
> >
> > Repeated the pressure test 4 -5 times and the results were consistant.
> >
> > The leak is less severe for cylinder #3. But the air flow is obvious
> > there. I
> > think these are enough to conclude that I have leaking rings on #1 and
#3
> > cylinders.
> > The leak was so bad it actually caused slight over heating during my
> > weekend trip
> > of 320 miles.
> >
> > The liner is new, with 800 break-in miles. I have to conclude that
Cofap
> > is junk.
> > Or at least the set I got is near junk. Further breaking-in probably
won't
> > make
> > any improvement as I have had 800 mile on it.
> >
> > My patience is running out for now. I won't try to fix it for the next
> > week or two.
> > I don't think I did anything wrong in istalling the liner. I did not
align
> > the rings.
> > According to Benny this is not likely a problem. I have heard that
Cofap
> > has a wide
> > range of quality distribution between junk and excellent. Can anyone
> > confirm this?
> >
> > David
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
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>

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