We currently have a Caterpillar 3412 engine in for overhaul for a marine operator, and we’ve found numerous issues.
I figured it might be useful to share exactly what we’ve found, as it’ll help you work out what you should be looking out for, and some of the reasons behind the problems.
During the initial visual inspection, we found:
- All of the bolts were severely overtightened (a sign that the engine has clearly been apart before)
- Several fittings were jammed in a non-threaded hole (where there should’ve been a core plug)
- One of the injector retainers was loose
- Heavy rust had set in on most assemblies
- Signs of previous rust on the liners so the engine may have been stored in a damp environment for a while
- The oil cooler was in very poor condition and full of copper shards in the water side
- The front main seal had clearly been leaking for a while
Once the engine was fully stripped down to bare crankcase, several fairly serious issues were found:
- The bearing shells had cavitation/erosion – likely caused by water in the oil
- The liners were severely pitted on the outside – this is caused by cavitation due to the design of the crankcase
Thankfully this was discovered now, as if this had gone through the liner it could have caused the engine to hydraulically lock, which would cause severe internal damage.
The new liners will be painted with a corrosion-resistant primer before install to help prevent this from occurring again in the future. The use of the correct genuine Cat coolant will also help prevent recurrence.
- The conrod small end bearings looked worn, however, have not yet been measured
- Cylinder heads have been stripped and visually inspected – all valves have steps and will need replacement
- Behind the plugs was a heavy build-up of carbon/oil/sludge
- Crankshaft scoring found
- The conrods have been measured without shells, however, the shank of the bolts are worn and allow movement
As you’d expect, we will be rectifying these findings in the most reliable, cost-effective manner, but we just wanted to point out the importance of getting the issues resolved before they turn into a bigger problem.
