Re: [Chrysler300] things that go BOOM

["Warren Anderson" <wranderson@xxxxxxxxxxxxx>]

To all weekend diagnosticians:

so... Dave Clelland finally decides to drive his 300G rag somewhere...
(yes, Peter Fitch, he DID drive it ! ) ...  after a 45 minute ride, he
arrives at a car show.....  and BOOM. Big explosion under the hood.


I would guess that the boom started on top of the engine where heated fuel
vapors and oxygen and a multitude of sources for ignition existed. The fuel
in the engine crankcase in this case had to come from the vehicle fuel tank
and then into the engine proper via two routes; the fuel pump and
carburetor(s) and/or short cutted directly to the oil sump via an internal
leak in the fuel pump.

We see a lot of engines with fuel contaminated oil. Flooding carburetors
used to be the major cause. The mechanical engine mounted fuel pump can also
be a cause but in my time working with carbureted spark ignition engines the
fuel pump has not been as much of a problem as has been sinking floats,
contaminated fuel systems and bad needles and seats.  On the more modern
stuff, fuel injectors and cold start valves will stick open or leak also.

My most flooded experience: 1942 White municipal bus originally from San
Francisco (converted to a six horse transporter). The thing had a  BIG
direct run electric fuel pump through a no-key classic White push-pull
ignition switch. The pump ran until the 8D battery on board ran dead and
filled the 12 cylinder opposed engine under the floor boards with an
enormous amount of fuel. The direct connection pump setup was part of the
bus when we bought it but for sure I do use oil pressure safety circuits for
electric fuel pumps now.

I had an encounter with a self professed consumate professional automotive
type just recently that had absolutely no comprehension as to how raw fuel
could get into the oil pan except through a block mounted fuel pump. Well,
it can enter through the intake system also and just a little bit will do
'ya.

Warren Anderson
Sedona,AZ



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