Hours from irreversible damageimage

Hours from irreversible damage

Engine Maintenance


We currently have a Cat 3406 in for an overhaul.

The overhaul was arranged due to engine failure, even though the engine was only overhauled 8,000 hrs ago by a different vendor.

Whilst the engine appeared in reasonable condition for the hours of running, when we tried to turn the engine to TDC we encountered what was to be the first of many issues!

Our engineers were unable to bar the engine over and noticed that two push-rods on number 5 Cylinder were bent, we also found damaged camshaft followers and a bent follower tang.

As they continued with this stripdown and inspection phase, they also found the following:

  • Ring gear damage
  • Crankshaft assembly would not turn in the case*
  • Damage to number 5 cam lobe due to the cam follower damage
  • All engine bearings were worn and scored, with some having uneven wear
  • Main bearing shells had been mixed, the shells fitted were half genuine and half non-genuine
  • Spun big end shell on No. 5 crank pin. (The bearing shell had been found crushed between the bearing cap and rod)

*The crank was mounted on the bench and found to have a bend of 2.95mm.

Fuel dilution in the oil was the culprit here – a fuel pump element had come loose leading to a high-pressure face to face seal becoming fretted against the pump body allowing fuel to pass into the engine oil.

We cannot tell which issue happened first and lead to such damage, but we can recommend the following to help prevent this from happening to you:

  • Ensure all replacement components fitted are the same spec as original
  • Use reliable, experienced service engineers for all work scopes
  • Source parts from reputable suppliers with certification where required
  • Seek expert advice at the first sign of any issues
  • Instigate regular oil sampling

This engine has been removed from an offshore support vessel and after the overhaul, will be used as a harbourside generator when the vessel is in port.

If you are unsure of your engine’s health or when it was last overhauled and would benefit from a comprehensive survey or overhaul, get in touch we would be happy to assist.

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