Date: Mon, 11 Nov 2013 02:00:20 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: My recent engine tear-down: All is good again
In-Reply-To: <CAHTkEuLAJB3z5fUKxjX0z78w7DPrNAFBgL1a1d9rDYJJYR-jkw@mail.gmail.com>
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Did you inspect the block? I have dealt with a number of these engines where
the block was the real problem. The side was only the residual symptom after
the burn through.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Don Hanson
Sent: Sunday, November 10, 2013 10:38 AM
To: vanagon@GERRY.VANAGON.COM
Subject: My recent engine tear-down: All is good again
84 tin-top/westie interior with a 93 Jetta 2.0 liter ABA/1.8 liter 8-vave
head (92 rabbit/jetta/etc) inline gas engine with a a 5sp and Vanagon
diesel-parts 50 deg mounting. digifant EFI.
Recently I 'lost' two cylinders in this motor after about 50k
miles. After getting good advice from people here and doing a
preliminary compression test, I pulled the head, leaving the motor in
the van. About 4 hrs of work there...a real mechanic probably coulda
done it in 2..
I found a blown cylinder head gasket, a small breach between cylinders 3 &
4, across the castings between the pistons. When I built this motor a
couple of years ago I was less than conscientious with my at-home head
milling job, quitting too soon, with some
discolored surface still showing right there where it blew. "Good
enough" I told myself at that time..."The headgasket will compensate
for that little "low" spot " Wrong, I found out. It did go for
about 50k miles before biting me.
Everything else in the motor seems fine. Valves look very good , no
wear apparent on the cam, the cylinder walls showed nothing bad.
So I got the needed parts to put it back together ($120 worth, including a
special 3-layer $50 head gasket) and this time, I was
meticulous about surfacing my head. I guess I spent about 2 hrs of
careful (and somewhat strenuous, shoving the head back and forth) lapping on
ever-finer emery cloth on a very flat table, finishing up with 320 grit.
This time, "good enough" was put aside and my completion-standard was
"perfect is OK" I also replaced the timing belt and the injector O-rings as
well as found that the green plug to the injector log, that had both wires
bare and shorting together...perhaps the cause of my intermittent 'smoking
sometimes during stop and go'...
FYI, the head torque specs from Techtonics Tuning are different from Bently
Books..(44ft/lbs+90+90 was what they suggested I use)
So I finished and tested yesterday...after a lot of initial smoke out the
pipe and some alarming bubbles coming into the expansion tank..("Oh
Brother!" I thought..."I get to do this all over again, the head gasket is
leaking again") . Everything settled down in a minute or two, the air all
came out of the cooling system and she runs like a new motor.
I'll finish up with an oil filter and new-untainted engine oil, a
re-check of the timing belt tension and some new fuel line...
Don Hanson
PS..Why did I choose to surface my own head? Couple of reasons.
First, I don't have a trusted machinist that I am familiar with.
Removing all the valve gear and restoring it after sending out is pretty
involved. It's been my experience that while machines are time-savers and
allow unskilled workers to accomplish difficult tasks, they aren't always
the only or best way to do something. The boys at T.T. mentioned they see
their fair share of botched machine jobs on VW heads and are particular with
where they send their machine work...
So, yes, my arms got tired and my brain got numb pushing and pulling that
lump around, but I know it is smooth and straight.
