A ferry with twin propulsion engine faced high exhaust gas temperatures on both the engines for many years, such as high that the exhaust manifold collapsed two times on both engines. The ship staff were unable to identify the root cause despite overhauling many components and installation of new components.
| Damage | Exhaust manifold collapsed twice. |
| Engine Make | Mitsubishi |
| Engine type | 12V52/55, Make |
| Vessel Type | Ferry/RO-RO |
| Reason | High exhaust temperatures of 480 – 580º C over years when the engine was in service. |
Investigation:
The engine expert was called onboard to find out the root cause of the problem. The engine performance did record high exhaust gas temperatures while rest of the parameters confirmed to the sea trial data. Later, it was recommended to inspect the fuel pump elements (plunger & barrel) along with the fuel injector nozzles.
Upon inspection and investigation, the marking and specifications on fuel pump elements and nozzle caps were wrong and does not confirm to the OEM specifications. The vessel ordered spares from the engine maker and upon complete overhaul of all the unit pump elements, the exhaust gas temperature of all the units in both the engines came down by at least 100 degree Celsius.
The Engineers onboard were happy and celebrated for solving this mystery which puzzled many over the years. It was decided to take the vessel out at sea to perform engine trails and check the operational parameters.
Surprisingly, while on sea trial, the exhaust gas temperatures started increasing and the morale of the engine staffs were crushed as the temperature gauge recorded increase in exhaust gas temperature. As the temperature kept increasing, there was a clear dark color plume at the funnel. But this time, the puzzle was very simple to solve while it did send shivers deep inside everyone. It was found that an additional felt filter wrapped around the silencer of the turbocharger was totally clogged with carbon from exhaust gas leaks from the exhaust manifold. The additional filter was in place to prevent the exhaust gas fouling the compressor side of the turbocharger. The filter was in use for about a month already and upon removal things turned up normal and it was a party time once again!
Lessons Learnt:
- It is recommended to use OEM spare parts always.
- The ship staffs should refer to the operating/spares manual and check for the proper spare specifications.
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About the Author:
Mr. Wolfgang Gensch has over 32 years of service experience with MAN B&W. Over the past 7 ¼ years while employed with MAN B&W, he has attended to more than 440 vessels for different purposes. In the past forty years, Mr. Gensch had attended to over 600 vessels and carried out different work covering all fields on diesel engines and turbochargers, from normal docking, to troubleshooting, to overhaul, repair and rebuilding work on older and newer engines. His area of expertise is quite vast from a simple inspection up to intensive repair work such as repositioning of crankshafts on 2-stroke engines. He is Senior Technical Consultant at DETC – Singapore.
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Nice article. How to consult with Mr. Wolfgang Gansch?