Date:         Sat, 21 Jul 2007 12:41:47 -0700
Reply-To:     David Kao <dtkao0205@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Kao <dtkao0205@YAHOO.COM>
Subject:      Re: scratch on heads mating surface for cylinders
Comments: To: Mark Drillock <drillock@earthlink.net>
In-Reply-To:  <46A25186.5050700@earthlink.net>
Content-Type: text/plain; charset=iso-8859-1

Good point, Mark. I agree. And yes the heads can be machined.

David

--- Mark Drillock <drillock@earthlink.net> wrote:

> There is no way that a pressure or leakdown test can mimic the nearly
> instantaneous pulse of 1000s of psi that the sealing ring sees every
> time that cylinder fires. It may leak only occasionally and only when
> the thermal stresses of combustion are high and the pressure cycles are
> 1000s of times per minute. Plenty of waterboxers pass the static
> compression and leakdown tests but can barely make it around the block
> before blowing coolant out with leaking combustion gases once the engine
> gets hot.
>
> If the scratch is deep, the head can be machined to remove it. No need
> for a replacement head just yet.
>
> Mark
>
> David Kao wrote:
> > The rings (head gaskets) are made of stainless steel. The heads are Aluminium.
> > I think the rings will not compress. It is the heads that may yield to the
> > extreme torque. But the torque is only 38 ftlb. It's enough to seal if all
> > surfaces are clean and flat. Minor scratch may be fine. But if you can not
> > eliminate the scratch by lapping it seems the scratch is deep.
> >
> > The only way to find out is to assemble the engine and do a pressure test
> > or leak down test. Any leak into the cooling chamber means replacement of
> > the cylinder head unfortunately. Whenever combustion gas is leaked through
> > the head gaskets into the cooling chamber it will push coolant out of the
> > cylinder head and raises the engine temperature by cooking the coolant.
> > The temperature sensor will feel it. The temperature guage will show it.
> >
> > David
> >
> > --- Benny boy <huotb@VIDEOTRON.CA> wrote:
> >
> >
> >>Hi Pascal, unless it's very deep and long enough so it larger than the ring
> >>itself, i would not put nothing there, combustion temperature are so high
> >>that most product will melt.
> >>
> >>That ring/head gasket will compress and sould fill the gap, but again, if
> >>not to deep.
> >>
> >>Ben
> >>
> >>On Sat, 21 Jul 2007 13:28:13 -0300, Giasson, Pascal (DNR/MRN)
> >><Pascal.Giasson@GNB.CA> wrote:
> >>
> >>
> >>>I have some small scratches on my heads, I think they got there from
> >>
> >>removing the metal gasket that goes between the cylinders and the heads, but
> >>not sur as I was really careful when removing them.  Anyway I tried to
> >>remove them with lapping compound and laping them with the cylinders, but no
> >>luck.  Is there a sealant that I can use or maybe JB Weld?  Thanks
> >>
> >>>Pascal
> >>>'84Westy
> >>
> >
> >
> >
> >
> > ____________________________________________________________________________________
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> >
>




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