Hot grass fire at Sun-N-Fun

On Sat, 08 Apr 2006 13:24:55 GMT, Dave S
wrote:

Sometime shortly after the catalytic converters were mandated, heat
shields were also mandated that are _supposed_ to
prevent this fire problem....



The heat shield cuts down on radiant heat from the CC, but if the
heatshield itself is hot enough and TOUCHES the tall dry grass, then you
still have a fire.

Dave
And any mechanic knows the heat sheilds often do not last more than a
few years before they come loose and rattle. Then they can either be
clamped on, welded on, or allowed (or helped) to fall off.

A minor missfire can also cause the converter to overheat. Imagine
what happens if the engine "diesels" on shut-down. My wife drove our
Corolla to visit her family in Windsor, and the cruise stuck, holding
the throttle partly open. When she shut it off(in neutral) it
"dieseled" and the cat must have flashed white hot, as it caused the
carpet on the floor above the converter to start on fire. The carpet,
a corner of the seat, and the console had been consumed by the smokey
fire before her sisterinlaw and nephew got the hose out and turned on.
We salvaged the car and got a few more years out of it, but if IT had
been on dry grass on a breezy day, that would have been the end of it.

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clare at snyder.on.ca wrote

A minor missfire can also cause the converter to overheat. Imagine
what happens if the engine "diesels" on shut-down.

We salvaged the car and got a few more years out of it, but if IT had
been on dry grass on a breezy day, that would have been the end of it.

Yep. I had an Olds that was suddenly having intermittent loss of almost all
power, then it would be fine. I was driving it one day and hit a bump, and
heard a strange "ker-thump" (that's technical car talk g) then it lost all
power.

Long to short, I started thinking about the 'ole potato in the tailpipe, and
how it behaved like that. I cut into the pipe downstream of the converter,
and saw that all of the pellets had melted into a perfectly molded lump,
just the shape of the back part of the cat. shell. When I hit the bump, the
lump rolled into the outlet, and shut off the exhaust gas flow. Really
lucky to trouble shoot that one!

It is hard to say how hot it had gotten to melt the pellets, like that.
Certainly hot enough to start a fire.
--
Jim in NC