Date: Thu, 24 Apr 2008 10:04:54 -0300
Reply-To: "Giasson, Pascal (DNR/MRN)" <Pascal.Giasson@GNB.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Giasson, Pascal (DNR/MRN)" <Pascal.Giasson@GNB.CA>
Subject: Re: Thoughts on Cracks between Valves on Heads?
In-Reply-To: A<91c8f9760804231548t1a3aef56t9e4369b45f448466@mail.gmail.com>
Content-Type: text/plain; charset="us-ascii"
Wes,
I have recently gone through the same thing as you. I now have 8 heads
(7 VW, 1 AMC) they all came from running motors. All the heads have
cracks between one or both valve seats except one of the 2.1 VW head.
Four heads came from engines that threw rods. Four came from engines
that still ran.
My conclusion from all this is that there are likely many Vanagons
running around with those hairline cracks between the valves. Many
drivers, like me, did (do) not even know that their heads are cracked.
There are no obvious symptom that I know of that are associated with
those hairline cracks.
I believe if the cracks go below the valve seats then they are not
suitable to reuse.
Pascal
'84 Westy
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of pickle vanagon
Sent: Wednesday, April 23, 2008 7:48 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Thoughts on Cracks between Valves on Heads?
So...
I'm planning on doing the heads on my van. I ordered the head gasket
kit
from Van-again, and Ken sent his instructions which look very good and
thorough.
Because I cannot afford new heads, I bought a pair of "very lightly used
heads" at roughly 1/3 the price of new AMC heads. The heads came off
the
seller's friends van after a rebuilt engine threw a rod (bummer), and
should
be practically new (say, less than 1500 miles).
The heads came today, and indeed, looked beautiful, at least to me.
They
looked like they had been run for a few hours and taken back off.
Anyways,
after cleaning the area between the valves with brake cleaner, however,
I
discovered the famous cracks between the valves.
Interestingly enough, the heads are one AMC head, one VW head. Both
have
the cracks (The AMC head between both pairs of valves, the VW head
between
just one of the pairs). There are no cracks in either going to the
spark
plug hole.
Page 15.17 of my Bentley has this note in the upper left corner:
"Cylinder heads with cracks between valve seats or between a valve seat
and
a spark plug thread can be used again without reducing service life
provided
that the cracks are not more than 0.5mm (0.019 in) wide or that only the
first coil of plug thread is cracked."
On the other hand, I am sure that there are many with the opinion that
any
cracks at all indicate impending failure.
In my case, the cracks are at most 0.1mm (none can be seen without some
sort
of magnification). And I believe the seller that they are as new as he
says
(and the rest of their condition seems to indicate this).
I'm wondering: has anybody installed new heads (VW or AMC), and them
pulled
them later, steam cleaned them, put them under a magnifying lens, and
found
no cracks between the valves? Or is it likely that these cracks
basically
always show up in the first few thousand miles, and VW is correct in
saying
that their presence alone doesn't indicate a significant shortening in
life?
In any case, I plan on getting the heads pressure tested tomorrow, but I
expect that they will pass. Assuming they do, who thinks I should expect
these heads to last for less time than (really) new ones?
Thanks very much for any thoughts.
-Wes