15/09/2025
This vehicle was recovered due to a non-start condition after it had cut out while being driven. Upon initial inspection, we confirmed that the engine was completely seized. We attempted to manually rotate the crankshaft with a spanner but found there was no movement at all.
When draining the engine oil, we discovered that it was contaminated with coolant. Based on this finding, we suspected that the engine would require replacement. However, it was critical to identify the root cause of the failure to prevent recurrence with the replacement engine.
Our diagnostic approach was to gain access to the crankshaft and remove the connecting rod caps sequentially, checking at each stage to see if the crankshaft could be rotated. After removing the lower oil sump, we determined that the upper sump could not be removed without first taking out the gearbox. However, gearbox removal requires rotating the engine to unbolt the torque converter from the flywheel — which was not possible due to the seized condition.
At this stage, we had to deviate from the workshop manual and carefully break through the upper sump to gain access to the crankshaft. This process was time-consuming, as the issue was ultimately traced to cylinder 4 — the last connecting rod to be unbolted.
Once access was gained, we confirmed that the big-end bearings on cylinder 4 were severely scored and had seized onto the crankshaft, which was preventing rotation. After disconnecting the connecting rod on cylinder 4, we were able to rotate the crankshaft and proceed with gearbox removal.
Further engine disassembly confirmed that the root cause of the failure was a failed oil cooler, which had allowed coolant to mix with the engine oil. This contamination led to lubrication failure and significant damage to the big-end bearings.
A replacement engine (supplied with a new oil cooler) was installed. All necessary calibrations and adaptations were carried out, and post-repair testing confirmed that all systems were operating as expected.