Date: Mon, 6 Dec 2010 11:26:52 -0600
Reply-To: Mike South <msouth@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike South <msouth@GMAIL.COM>
Subject: Re: Vanagon engine fire or mishap in Roanoke, Va
In-Reply-To: <4cfadf44.4bfde50a.3584.ffff8af3@mx.google.com>
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On Sat, Dec 4, 2010 at 6:38 PM, David Beierl <dbeierl@attglobal.net> wrote:
> At 07:02 PM 12/4/2010, David Clarkson wrote:
>
>> a vanagon westfalia that appeared to have had some sort of fire (probably
>> fuel line related)
>>
>
> Hi David -- I'm just curious what led you to the conclusion that it
> was probably fuel-line related.
>
> I'm not saying it wasn't, and it's certainly a very poor idea to have
> gasoline spraying around the engine room. But unless gasoline
> behaves differently than it used to (and it might -- it's more of a
> mixture of heavy and light components than when I was young) you can
> spray it on a hot exhaust pipe without it catching fire* (whereas of
> course a small spark will ignite gasoline vapor).
I think other people have pointed this out, but I just wanted to put it
together succinctly in a direct reply, for future people who might be
reading this and not digesting the entire thread.
The problem with this as a counter-argument to the idea that it was
fuel-line related is that it assumes a fuel-line related fire must be
ignited by fuel touching the exhaust pipe.
Scott pointed out that anywhere that electricity is leaking would be enough
to set off the resulting vapor. A fuel line break that sprays fuel anywhere
on the engine would generate a cloud of vapor that only needs one spark to
set it off, and it could be a spark that has been happening on a daily basis
in your car but not causing enough performance degradation for you to
notice.
Your engine might have spark leaks right now, in other words, that you don't
know about. So could anyone's. So I would think that paranoia-level
attention to fuel lines is warranted in spite of the fact that you can spray
gasoline on an exhaust pipe without ignition--in a spark-free environment.
Right?
mike
> Oil, OTOH, dropped
> on a hot exhaust will burn. Under normal circumstances there aren't
> any sparks available in the engine room, unless of course the
> sparking inside the distributor or from the ECU and fuel pump relays
> can do it. I'm guessing that with proper distributor cap/box seals
> it can't, but again I don't know for sure.
>
> *I think this was the basis of one of the Car Talk puzzles twenty
> years ago. Not that I was young twenty years ago. <g>
>
> Yours,
> David
>
