Date:         Thu, 19 Jun 2008 18:21:50 -0700
Reply-To:     John Bange <jbange@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Bange <jbange@GMAIL.COM>
Subject:      Loud Engine
Content-Type: text/plain; charset=ISO-8859-1

A friend of mine with an 86 passenger van recently asked me to help
him diagnose a minor electrical issue, as his regular mechanic (Jack
in Venice Beach, for those who knew him) had DIED after being crushed
under a Vanagon belonging to another friend of mine--- always use jack
stands, NEVER trust a jack... but I digress...

Anyway, I fixed the problem (bad ground!) easily, but when I started
up the engine, it sounded REALLY loud. The engines on my two vanagons
are really smooth and quiet. This one gives off a fairly loud, throaty
"burble". It's not an exhaust leak sort of noise, and it's not a
metallic clanking or clacking.... it's just a funny sort of rhythmic
"glomp". Not quite a "thump", but close. He said it ALWAYS sounded
like this, and he's put over 20K very hard mountain and desert miles
on it since he got it, so  it's obviously not something ready to give
out. The guy he got it from said it was a newly rebuilt engine, and it
definitely looks it-- very clean, fresh gaskets and hoses, no leaks.
All the plumbing and hard parts were clean and shiny, no rust or
leaks, all original paint too. Compression was good on all cylinders.
The only thing I could think of was maybe a valve adjustment issue...
maybe an valve opening late? The only thing I found suspect was the
left rear adjuster, the exhaust valve on the #4 cylinder. It was
cranked in far enough that the top was flush with the lock nut. The #2
exhaust adjuster on the other side, which runs on the same cam, is
adjusted roughly the same as all the others. What to do... I went
after the obvious, the one adjuster of the 8 that looked different.

 I experimentally loosened this to roughly match the others and left
it a couple days, then started it up and ran it a while. The valve
ticked like CRAZY and the lifter never pumped up, so I just readjusted
it properly, which left it back flush with the locknut. Either way,
the engine STILL made that same klumpy-thumpy-throaty rumble. Now a
couple days later, I'm sitting here thinking: why would the #2 and #4
exhaust valve adjusters be so dissimilarly adjusted when they both
operate off the same cam? Could it be a bad lifter? Simply a heavily
reground cam lobe for #2-#4 exhaust that needs the adjuster cranked in
farther and maybe the #2 isn't cranked in enough? If that's it,
wouldn't the #2 be "ticking"?

The only other unusual  symptom is lower than usual gas mileage---
17-18MPG highway on a manual tranny. Voltage on the O2 sensor shows
normal half a volt, fluctuating. I'm going to take my wideband O2
sensor and meter out with me next time and check out the quality of
the exhaust output in more detail.

So I'm fairly stumped. The main symptom is the loud rumble of the
engine, which is DEFINITELY not normal. Anyone have any insights?
Clues to offer?  He's driven it like this for a couple years now, so
it's not a show stopper at all--- it's just a personal vendetta for me
now! I must find out what that noise is about!

--
John Bange
'90 Vanagon - "Lastwagen"
'90 Vanagon GL - "Wiesel"