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marinediesels.co.uk
Horror Stories
ZA40 Mishaps
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Mishap Number 1:
Pump Drive Dropped Off
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The ZA40 can be fitted
with engine driven pumps.
In this first
breakdown The pump drivewheel fitted on the front end of
the engine became detached whist the engine was running,
damaging the engine casing. The engine was relatively
new and and had only run a few thousand hours. The first
the watchkeepers knew about it was when the engine shut
down on Low LO pressure. As can be seen from the photos,
the bolts holding the wheel in place had become
unscrewed and had become badly bent. Leads to suspicion
of incorrectly torqued bolts and locking wire of
incorrect specification, incorrectly fitted.
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End Cover and Drive Gear Removed from
Engine |
End of Engine Showing Vibration Damper
and Fixing Flange for
Drive Gear |
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Fixing Bolts and Pieces of Locking
Wire Retrieved from Engine Casing |
Gear Drive on Pump Showing Damage to
Teeth |
Mishap Number 2:
Cracked Inlet Valves
The next sequence of
photographs show the damage caused when an inlet valve cracked
and broke. Pieces of the valve hammered around in the combustion
space damaging head, liner and piston crown before wrecking the
turbocharger.
The Final photograph
shows how repeat of the failure was avoided during maintenance:
As part of the maintenance routine introduced, the valves were
crack detected during unit overhaul. This example was found to
be cracked and given a sharp tap with a hammer.
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Damaged Head and Valves
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Close Up of Damaged Valve
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Damaged Piston Crown
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Damaged Turbocharger Blading
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Inlet
Valve Broken Across Crack
Mishap Number 3:
Failed Bottom Ends
Overloading due to
incorrectly timed fuel injection led to failure of two bottom
ends. Some of the white metal from the bearing found its way to
the spherical top end bearing and damaged that. A major repair
involving crankshaft machining and regrind was required.
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One of the Damaged Crankpins
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Wiped Bearing Shells |
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Back of Bearing Shells Showing
Overheating
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White Metal Debris
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Damage at Piston Top End |
Re-Machining Crankpin |
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