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Wartsila’s User Group Forums 50 SG Engine Oil Mist Separator Failures

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  • #2049

    We’ve had two Alfa Laval oil mist separator failures on different units, both at around 800 hours.  In both cases the oil mist separator motor was found overheated and investigation revealed a bent shaft where the disc stack is attached to the motor.   These were found in-service, so we’re not sure if it happens upon startup as they come up to speed, or if they become unbalanced in operation and then bend the shaft.  In both cases the disc stack contacted the inside of the casing causing the rotating assembly to lock up.

    Wartsila is replacing these under warranty, but with 2 failures out of 8 units, we’re concerned about long-term reliability.  Is this a common failure point on these units?

    Thanks in advance for any experiences you can share.

    Dave Mordecai

    City of Tallahassee Hopkins Station


    Follow-up to my previous post:  We’ve now failed 6 of 8 total oil mist separators, and found the root cause to be the controls for the oil mist drain tank pump.  These systems were apparently never commissioned by our startup team and were left such that the pumps will never start.

    We’ve recently heard from another Wartsila tech that these oil mist separators were installed up high near the cooling water expansion tank on previous units, and ours are the first he’s seen installed down on the pipe rack.  The elevation is roughly level with the crankshaft centerline, with a small drain tank underneath and a diaphragm pump that is controlled by a hi level sensor and air solenoid.

    If you arrangement is similar to ours, I’d like to know if you’ve had any issues with the system.  If your oil mist separators are located elsewhere, I’d like to know how they are drained, as our setup appears to be a flawed design and we see room for improvement.

    Thanks in advance for any feedback,

    Dave Mordecai, City of Tallahassee Hopkins Station



    UMERC has the same arrangement with the oil mist seperators installed low at the pipe rack.   We haven’t received the Tech Rep report yet, but  the Wartsila Tech rep recently modified the system including installing a vent to relieve pump pressure.  Prior to the modification UMERC had failed two motors.


    We have 12 Alfa Laval Oil Mist Separators, engines have around 7000 hours and so far the failures we have experience on them are:

    Diaphragm Pump Inlet port Broke. We think this was an overnight issue during installation, after replacing that one no more issues have been found but recently was noticed that they are obsolete and new model is in the market.


    ABB VFD’s: 3 of them showed issues caused by vibrations and they were addressed adding some rubber supports. After that no more issues. All the rest of the VFD’s were found broken due to vibrations as well in the base plate but they are working fine with no issues.

    1 Motor replaced: Thermal protection inside the motor failed. Motor was replaced and we received a different model that is working fine. During this troubleshooting it was found that not all the units were wired the same, some of them, the motor thermal protection was not installed.

    Hope this helps.

    Ruben T.




    Follow up to my last post: We’ve modified our oil mist separator drain tank piping to provide a dedicated vent for the tank so it will fill and drain properly.  The original design had only a single 1″ connection for oil fill and vent. Reply with your email address if you would like to see photos.

    We also found that the level sensor and wiring that controls the air solenoid for the pump will not work as designed and are awaiting Wartsila’s response.   It is a vibrating fork level sensor that requires power at all times and they used the same circuit to switch the air solenoid.  Since it is hot all the time, the air solenoid will remain energized and run the pump continuously.   We expect the fix to be a different model of the level sensor with a set of dry contacts for a separate switched circuit to power the air solenoid.

    Dave Mordecai –  City of Tallahassee Hopkins Station


    Dear Dave,

    I’m interested in the foto’s. We are having the same problems. We have already changed 6 separators.
    We also asked Wartsila, but no reply. We are still awaiting their answer.


    We have 8 each installed on our wartsila/vasa 16v32’s. All of them had been replaced way earlier before the estimated rebuild/replacement periods in the last couple of years. We have the 1st generation (1 left installed) and the latest versions as well. Neither wartsila nor alfa laval have really provided any good support towards mitigating the issues.

    Same issues, shafts getting bend, bearings going out. However our recent fix seem to have decreased failure rates. We double checked how level each unit was and reinforced installation by making sure they were solidly bolted down and used rubber mounts where there were more vibrations on the base installation areas.

    Still kinda early to really tell, but hopefully this works.

    • This reply was modified 4 years, 3 months ago by .

    Hi Dave,

    Would you please send photos to

    Pete Olsen, Coffeyville.


    We have one unit that will not start when the level sensor is dipped in an oil cup. I am suspecting that it is a wiring problem on that one as we took a level sensor from another unit that is working and still could not make it work.



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