08-10-2012 03:57 PM
Over the last year there has been a change to the fuel injection pump delivery valve. Since then we have had a large problem with failure of the delivery valves and at the start of this year started having failures of the fuel injection pump element cracking. This has became a very large problem with as many as 8 failures per month. Is anyone else having this type of problem? Most of the failures are on material purchaced in the last year.
08-17-2012 05:36 AM
The delivery valve on M43 injection pump was not changed in his characteristic and its basic design. Actually, there is an issue with a small number of delivery valves that might cause seizing pump elements due to broken off parts. Known customers to be affected have been contacted.
The common reason of cracked pump elements is cavitations at the delivery bores. This can happen when the deflector bolts are worn. Please check engine manual for service interval.
I would like recommend contacting your MaK service dealer to have the damages investigated. When contacting your MaK service dealer please provide engine no., history of parts and pictures of the damaged parts. This helps you avoiding additional cracked pump elements by knowing the root cause.
Kind regards, Zement
08-29-2012 05:06 PM
thank you for your input the last pump that failed had 5,465-hours of operation and the deflector bolts showed wear. This is a new problem that started this year and 90% of the failures are on new pumps installed last year and built in 2011. Other than the new style delivery valve the only other change was the removal of the fuel dampers from the system.
11-21-2012 08:51 AM
The injection pumps on MaK engines are plunger pumps controlled by a control helix. Every time when the control helix passes the delivery holes in the barrel the injection pressure will become back to normal fuel pressure. During this pressure change the fluid phases becomes gas phase at certain places around the delivery holes and the control helix. Cavitation effects will take place where the gas bubbles imploding close to surfaces. This physical phenomenon is normal and the plunger and the barrel are protected by the baffel screws. Once the baffel screws are worn, the cavitaion will affect the pump element and finally damages like cracked barrels will occur. The pictures of the pump element of this engine show severe cavitation attacks.
Please check your fuel oil quality for easily gasing components and maintain your baffle screws according to you engine manual (job card A5.5.07.03.02.00; (checking every 3750 hrs for wear; latest exchange at 7500 hrs)).
Pressure waves created by the injection pumps will be limited by throttle screws in the injection pumps. The height of the induced pressure waves into the fuel system does meet the classification society rules. The fuel pressure dampers that have been installed on this engine type have no influence on the cavitaion in the injection pump. Therefore, this measure has nothing to do with cracked barrels.
Kind regards, Zement
02-21-2013 11:26 AM
We have been checking and maintaining the baffle screws now every 3,000-hours and changed out a lot, most with less than 5,000-hours. My next question is there any special tests that I can have performed on the fuel oil?
This remains to be a very bad problem.