Diesel Fuel In Gasoline Causes Engine Damage

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 diesel 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?

pontiac grand prix


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 all 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 sensor, 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. Not all engine wwill do this, but your IS what is called an "Interference Motor". Which means if the timing chain breaks, valve damage will occur. 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.

This is going to be averu expensive repair. If you need any more help, just let me know.

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