Date: Mon, 7 Nov 2005 14:05:35 -0800
Reply-To: Michael Diehr <md03@XOCHI.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Michael Diehr <md03@XOCHI.COM>
Subject: Re: Help diagnose Cinco
In-Reply-To: <000001c5e3e2$db8c0d70$6400a8c0@masterpc>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
I'm not an expert, but I don't think it's burned, so much as it has
been crushed. You can see several grooves cut into the spark plug
that are just about the right size and curvature to match the edge of
a valve. Most of the edges look sheared, rather than melted to my eye.
So do you suppose this cylinder was running lean, and that caused the
valve to break, which then ground up the spark plug?
On Nov 7, 2005, at 1:33 PM, Dennis Haynes wrote:
> This was caused by pre-ignition. Ping, knock, whatever some wish to
> call
> it. Most likely cause is over-advanced ignition timing and maybe a
> lean
> fuel mixture. Overheated engine (or that head) could contribute. If
> you
> melted a spark plug, what condition is the piston and valves in.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
> Behalf
> Of Michael Diehr
> Sent: Monday, November 07, 2005 1:32 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Help diagnose Cinco
>
> Aha! The smoking gun has been found.
>
> Step right up folks, it's "test your knowledge" time.
>
> To recap: Old van with 150k miles, was running fine, suddenly lost
> power and wouldn't start again, about 10 miles after a fillup.
> After towing to a gas station started once, then immediately died
> after about 1 second. Sounded normal when it cranked. Wouldn't
> start again.
>
> At first, thought a hall sender problem, replaced distributor and re-
> aligned the distributor gear which was installed improperly by the
> PO. This turned out to be a red herring.
>
> Afterwards, still no spark on the #1 plug (as measured by a timing
> light on the #1 spark plug wire). Spark observed, however, when
> connected to the wire between the coil and the distributor.
>
> So here is today's super stumper question:
>
> Why would there be spark at the coil wire, but not on the #1 spark
> plug?
>
> 20 points if you get it here.
>
> Hint 1: It's NOT one of the obvious answers: The Distributor, coil,
> hall generator, hall sender, and all wiring is new and functional.
> 10 points if you get it now.
>
> Hint 2: Although the #3 spark plug looked a bit black, it was in
> otherwise good condition. I had not as of yet pulled the #1 plug.
> 5 points if you guess it now.
>
> See here for the smoking gun: http://xochi.com/vanagon/Plug1.jpg
>
> So for the next question, what happened to cause this?
>
>
>
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