ZF301A loud whine then no forward or reverse

[Mike]

Running the boat at 2160 RPM’s and port gear started making a whining noise and if the RPM’s changed so did the intensity of the whine. the whine stopped all of a sudden and so did any movement of the port shaft. Oil in gear box is good and is not burnt, no metal or debris in filter. Had a burnt rubber smell in engine room for about 2-3 minutes then it went away – heard no other noise other than the whine, and now there is no oil pressure at all. Tried to finish the trip on the stbd engine at 11-1200 RPM’s and within 2 hours it too started making the same whine, lowered it down to 900 RPM’s and made it to a marina about 5 hours later.
Engines are 6CTA 8.3 420 Hp with 2470 hours on each.
question is – would a failed coupling create that kind of whine that would be deafening in the aft stateroom while under way? Could the chances of having the same part fail on both gears be due to the stbd engine trying to pick up the slack for the entire boat the rest of the trip?
Just trying t figure out which part to tackle first – oil pump to see if that’s bad or go ahead and slide the Gear back to take a look at the coupling.
Any help would be appreciated.

Topic

[Tony Athens]

Torsional Coupling failed

Look at the pics.. You have Bonded Rubber torsional coupling that has failed completely, and the other is 1/2 thru the complete failure (a few more minutes at medium power should do it) .. That’s what these coupling do..Whine, slip, burn rubber, and finally let go completely.. Welcome to the world of “modern Monkey Motion” torsional couplings

You need to pull the gears to “see” what you have.. More that one type for your gear.

Tony

[Author]

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