Date:         Sat, 4 Nov 2000 03:51:39 MST
Reply-To:     d t <tinkerman@USA.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         d t <tinkerman@USA.NET>
Subject:      Which cylinder isn't firing??
Content-Type: text/plain; charset=US-ASCII

Hello Volks,

Lately, I've started smelling gasoline while driving my 2.1L 1990 GL.
Alarmed, I immediately checked for any gas spilage or moisture under the van
(looking for the dreaded fuel hoses failures I've heard so much about on this
list) but found no sign of it. I also noticed that the Vanagon is not pulling
as usual (top speed of 75mph instead of the usual 88mph...:-), vibrating more
in idle and taking more time to stabilize in idle after cranking.
My conclusion: one (or more) of the cylinders is not firing, resulting in

reduced power, uneven running and unburned gas smell. Occasionaly, I feel

minute power surges suggesting that the faulting cylinder/s do/es fire
sometimes.
I checked the ignition cables but all were fit well. I took them off the spark
plugs and all seemed clean except for one which was a bit oily inside
(suggesting spark discharges over the oily path instead of normal ignition
inside the cylinder). I cleaned it with fuel but to no avail.
So I think one of the plugs is dirty INSIDE (I wonder how it got dirty in the
first place: not tightened properly or the gasket failed?). 

Before I start removing the plugs (I'd prefer to avoid this if possible,
because I once shreaded the threads on one of my motorbikes plugs...:-( ), can
anyone point me to a debug procedure (in the Bentley or Haynes manuals) to
find out which cylinder is not firing externally (e.g. if it's an external
ignition cable or distributor problem).
I tried to improvise an "ignition voltage sensor" by putting a Neon bulb next
to the spark plug ignition cables (at the end of a large stick of
course...:-), with no results.
I know it's probably a dirty spark plug, but this factory overhauled motor has
only 40K on it's clock and it's been serviced regularily, so there should be
no reason for one spark plug getting dirty suddenly (unless it's a sudden oil
seal failure...:-(
Here's an idea: has anyone found a dirty spark plug just by measuring
resistance from tip to ground (without removing the plug)?

Last question: does anyone really put the anti-seazure copper compound on the
spark plugs threads before installing them (as recommended in the Haynes
manual) or is this just for "pharmaceutical" mechanics?...

Cheers,
            T-man

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