2004 Pontiac Grand Prix. Vehicle had a 50:50 mix of Diesel Gas put into it when it already had
some gas in the tank.

The car ran approximately 18km when it lost power and started making noises.

All spark plugs had been smashed and had bits of melted aluminum on the porcelain. Crown on
one piston was broke off. Piston rings damaged. This vehicle did not have any previous problems
until this fuel was put in. The
mechanic that looked at the car said that bad fuel would not cause
engine damage. That the damage had to be caused by something else. Would diesel mixed in the
gas and ran through the system cause severe engine damage. What kind of damage could that
be? What do we look for?

Thank you for the tip/donation.The answer is YES.
A diesel/gas mix can cause this engine damage. Diesel and gas obviously have very different
properties. They burn in a completely different way.

While driving, the unburned fuel in the cylinders was probably pooling up in the cylinders. A gas
engine cannot run on liquid fuel. A cylinder that begins to fill with liquid will cause that cylinders
pressure to go sky high since there is less area for air, the cylinder walls will have the oil washed
off. The cylinders will be very unbalanced as it is running.

The shear compression of a liquid will cause spark plug and piston damage. Flakes of material on
spark plugs is because the piston(s) were starting to come apart, and metal was being
transferred throughout the engine. The computer was trying to compensate for the strange
readings on the oxygen sensors, injector pulse would be changed, timing would be changed, and
the engine would go into an unstoppable failure.

With such an difference in cylinder pressures, the timing chain may have jumped/broke, and caused
the pistons to hit all the plugs. Although as stated above, the extreme pressures in the cylinders is
enough to do that, and to break a piston.

While driving this way, there were VERY violent things happening in the cylinders. Cylinder
temperatures would be different from cylinder to cylinder, etc. The engine should be replaced, all
the injectors replaced, fuel pump replaced, fuel tank, lines, fuel rail cleaned out, fuel filter replaced,
oxygen sensors replaced,
catalytic converter checked for damage.

If you need any more help, just let me know. Thanks again for tip/donation- KK.

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Diesel Fuel In Gasoline Causes Engine Damage