Case of the Month: Engine Failure

Aug 1, 2018 by

An automotive repair shop serviced a 2006 Ford F450 turbo diesel engine.  Roughly 100 miles later the engine failed.  GEI was assigned to determine why the engine failed and if the work performed had anything to do with the engine failure.

The repairs that were recorded on the invoices included replacement of the head gaskets, valve cover gaskets, and O-rings.  The truck had a little over 202K miles on it.

Our expert inspected the vehicle at a local Ford dealer.  The vehicle’s engine was partially disassembled before he arrived.

Engine after removal

The upper part of the right cylinder head, which houses the camshaft, was removed before he arrived.  The cylinder head was removed from the block at the beginning of his inspection, which revealed the internal damage and the cause.

Cylinder head with broken valve

The damage to the engine included a broken exhaust valve in the # 7 cylinder, which is the rear cylinder on the right, or passenger, side of the engine.  The top of the piston was damaged, as was the rocker arm for the #7 valve.

Top of damaged piston on the left

Combustion chamber for # 7 cylinder

The truck was equipped with a 6.0-liter turbo diesel engine.  This particular model possessed four valves per cylinder, two exhausts and two intakes.  As an internal combustion engine is operating, the temperature reaches 650 degrees C. at the exhaust valves.  Over time and mileage with the engine operating and then turned off repeatedly, the change in temperature can cause the exhaust valves to become brittle and, on occasion, break at the valve stem, just below the head of the valve.

That is what happened on this vehicle.  When the head of the valve broke from the stem, the head then fell into the combustion chamber, and became a loose foreign object.  The loose valve head made multiple contacts with the piston that was traveling up and down in the cylinder, damaging both the piston and the cylinder head. Some of the smaller broken parts transferred to other cylinders.  Minor damage was found on the # 3 and # 5 pistons.

The cause of the engine damage/failure was a direct result of long-term wear-and-tear.  The exhaust valve in the #7 cylinder broke from long-term wear and mileage on the vehicle, which in turn, caused the damage to the pistons on the right bank and to the rocker arms.

Invoices for earlier repairs detailing gasket replacements

The repairs to cure oil leaks that were performed 100 miles earlier by the shop did not include any work on the valves.

Our expert determined that the earlier shop repairs did neither cause nor contribute to the engine failure. 

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