Date: Sat, 26 Jan 2002 12:42:43 -0600
Reply-To: Stan Wilder <wilden1@JUNO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stan Wilder <wilden1@JUNO.COM>
Subject: Re: Aircooled lifter noise
Content-Type: text/plain; charset=us-ascii
G. Matthew Bulley wrote: Jake Raby and I have a difference of opinion on
this matter of
un-adjusted valve clatter, and I think I should point that out. It is
his assertion that valve clatter is (at least in part) the sound of the
valve slamming closed against the seat, and this in turn is partly to
blame for valve seat destruction or loosening. I disagree.
-----------------------------
Stan Wilder replies:
After restoring several Westfalia and building many engines I have to
agree with Jake.
After you've done the homegrown cleaning procedures and adjusted the
lifters and not gotten the desired silence.
Its best to do a compression test or cylinder leak down test.
In almost every situation where the homegrown cleaning and simple
adjustment procedures failed to silence the valve noise I found bad
seats. Not necessarily dropped but loose or getting ready to drop.
In rare situations I've gotten the lifters to quieten by removing and
reinstalling the rock arm assemblies (removed for inspection of adjusting
screws and valve stem contact areas.)
I've had and run engines with loose seats that just occasionally lost
enough compression to make the engine hard to start. Some of them have
run as much as 10K with this near fatal condition.
Ultimately the seat either dropped enough to keep the valve open also
denting the piston top, worst still I've had loose seats and the seats
have hammered back into the head leaving the seat floating in the port.
I've seen intake and exhaust valves with this condition. (pictures by
request). If your intakes drop out or hammer back I'd blame that on poor
rebuilding. If you Exhaust seats drop I'd blame that on long use and
overheating.
Cracks are caused by a several problems with the foremost being heat then
poor welding repairs.
I've gotten 140 K out of both VW OEM heads and AMC (made in Spain) heads
so the valve dropping problem can be attributed mostly to abuse of
overheating. Its not as common as most of us are led to believe.
Stan Wilder
On Sat, 26 Jan 2002 11:25:28 -0500 "G. Matthew Bulley"
<gmbulley@BULLEY-HEWLETT.COM> > I propose that valve clatter is produced
solely as the slack in the
> valve train is eliminated by the lobe of the cam coming around and
> slamming the rocker arm tip against the tip of the valve. Having
> slack
> in the distance between the rocker arm tip and the valve does NOT
> slam
> the valve CLOSED (as Jake asserts), because the entire valve train
> is
> under spring load as the cam lobe retreats, and therefore there is
> no
> sudden slam, jus the normal valve closing. Think about it.
>
> Either way, well-adjusted valves are important to longevity and
> efficiency for your motor, so let's get them right.
>
> If your valves are still noisy after a few miles on the road, I'd
> suggest a chemical treatment to free up the sticky lifters PRIOR to
> messing with the adjustment. Sometimes crud fouls the hydraulic
> lifters.
> I wrote a LENGTHY description of how to do this back in 1998 or
> thereabouts, and I am sure you can find it in the archive.
>
> In essence, you are going to swap your oil out for a 50/50 mix of
> 10-w30
> and ATF transmission fluid and a new filter; high-idle it in the
> driveway for 30 minutes (do NOT drive it). You could also include
> an
> entire quart of MMO don't overfill.
>
> During the high idle, the clatter will go away, and you will smile,
> but
> keep it at high-idle for a full :30 minutes to continue the clean
> up.
> Swap the filter and oil to whatever you normally use. Drive it for
> 100-300 miles. Change oil and filter again.
>
> *IF* the clatter doesn't go away, readjust the valves. As for the
> great
> "preload" debate, I've used 2 turns, 1 turn, 1/2 turn, and no
> preload. I
> have no opinion other than to say that 2 turns is (IMHO) excessive.
>
> Last note, some say that MANN or VW OEM filters are best to solve
> this
> issue, particularly for WATER cooled flat fours, as they have
> better
> flow characteristics. I won't even go there. They may be right, but
> I
> can't justify the $6.00 cost. I don't share the philosophy that oil
> has
> to be sanitized to be clean enough to prevent wear, and I don't
> believe
> that *some* cheaper filters are just fine if you keep your oil
> changed
> regularly.
>
> I use Fram PH8A, which is a MUCH larger filter than the OEM, and
> has
> been my filter of choice for type 4's since the mid eighties. Buy
> the
> "extra guard" if your FLAPS has it.
>
> Telling you this though is like telling the Mother's Against Drunk
> Driving list that I put bourbon in my kid's night-time feeding so
> that
> they will sleep well. Flame all you want, you won't get me to
> switch.
> (from the bourbon, or the Fram)
>
> Happy motoring.
>
> From historic, walkable Mount Olive, NC,
>
> G. Matthew Bulley
> Bulley-Hewlett
> Corporate Communications
> Business: www.bulley-hewlett.com
> Alliance: www.ntara.com
> Home: www.MountOliveNC.info
>
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