I recently had one fuel injector go out on my drill rig whitch is using a CAT 3406 on the deck. I changed all 6 at one time. Immediatley after replacing the injectors the engine started using 1 gallon of oil efter every 12-14 hours of use. After approximatley 50 hours of operation the engine threw a rod through the side of the block. Any ideas??
The engine never heated up or lost oil pressure.

When you say the injector went out what was it doing? Was it dumping fuel into the cylinder? Was the engine oil contaminated with fuel and if so was it changed? If the injector was "pissing" fuel into the cylinder it may have burned the piston crown.

The bad news is the oil consumption problem should have been looked at as soon as the problem was noticed. If you do a failure analysis on this engine I would pay attention to the cylinder that had the bad injector. Pay attention to the piston, rings and cylinder walls of this cylinder and look to see if the piston shows any damage in the form of a partially melted piston.

The 3406 is a tank of a engine with a great service record. Properly maintained and operated they are a very long lasting engine. I have overhauled many of them in trucks over the years that were pushing well over 1 million miles.

One suggestion would be to start a UOA (used oil analysis) program if you are not doing one now. It is a great way to catch problems before they become a failure.

Here is just a thought on the engine throwing a rod. If when the engine was stopped, fuel drained into the top of the piston and then when the engine was re-started the fuel was trapped in the top of the cylinder and could not be compressed. This would bend and damage the rod and lead to the eventual failure.

Harv