ZF Marine IRM280PL gear rattle / chatter

[Mark Kiehl]

I have a ZE Marine model IRM280PL transmission coupled to a Cummins 6BTA5.9M3 330 hp engine in my 1999 Nordic Tug 37 with currently just over 3000 hours on them. Ever since I purchased the boat at 2010 hours, I heard the gear rattle/chatter when at idle speed and the transmission in gear (only at that time). A slight increase in engine speed would eliminate the rattle/chatter (similar result to what was posted on your website). Last year I checked all transmission pressures and confirmed they were within specification, and then added a pressure sender / gauge so I had some means to monitor it. Last Nov 2017 we started a trip down the Atlantic inter-coastal waterway (ICW) at 2744 hours. Now at just over 3000 hours, the rattle/chatter occurs at between 900 and 1200 rpm while in gear. We operated the boat at that rpm range a lot while traveling down the ICW. Should I be concerned? Ignore it?

Topic

[Tony Athens]

If you are getting gear rattle or clatter above an idle, and especially above 1000 RPM, your torsional coupling is most likely ready to fail, or has completely lost its “damping qualities”, or both..

Yes, I would be concerned..

Only solution, slide back the gear or lift it out and replace it.. There are not less that 3- styles for this engine / gear arrangement, and long term fied experience has shown some are better than others..

If you an open the attached “zip” file” and download the pics, you’ll get a better idea of what is going on..

Tony

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