I'm wandering if anyone can clarify what may have happened to my v10 engine. I have a 97 Fleetwood Motorhome with the superduty chassis V10 engine. After sitting for a few months last winter i went to start it up in the spring the motor emmediately threw a connecting rod right through the block. It only had 38,000 miles on it i never had a problem with the engine it ran perfectly up till then. It was the first cylynder where the rod broke at the front of the engine. After taking it appart i notice the rod looks like it actually bent then just snapped. The weird thing is the crank looks fine the cylynder looks fine but the rod just snapped in half. Is this hydrolock? I did start the engine a couple times over the winter but before this happened it was probably about three months since i started it. Thanks to anyone that may have input into why this happened just want to make sure it does not happen again.

 

I'm assuming you pulled the heads off during the teardown. What did you find in the cylinder above that piston. The bent rod would indicate that there was SOMETHIMG incompressable in that cylinder. How was the head gasket?

 

What do you mean by incompressable in the cylinder? Such as what? I did not see anything in the cylinder above the piston. Don't think there was anything wrong with the head gasket maybe should have checked it out a little better before i tore it off the block.

 

Sounds like hydrolock.

 

Ok it does look like the top of the piston with the broken rod is does have some gouges in it almost along the edge of it about 3 or 4 inches long. Almost looks like from the edge of the valve maybe. Just looking at the valves they look fine?

 

Something incompressible... like water.

 

A leaking fuel injector could have filled the cylinder with fuel causing a hydrolock. Or coolant or water got in somehow.

 

Bingo! I have seen this before and the common denominator is the vehicle with the V-10 sat for a long period of time.

Try this scenario. When the motor home was parked "a few months ago" I bet noting was prepped for long term storage. The fuel left in the fuel rails and fuel injectors varnished, which caused the injector to stick open when you fired the engine up.

Since the injector was momentarily stuck open, the combustion chamber filled with fuel, the cylinder hydrolocked and the rod broke when the rest of the engine tried to compress the one cylinder.

Next time use Stabil before you park it.

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