The Gear Box - the story so far ........ 24 May 2015

Tashi Delek
Mike & Carol Kefford
Sun 24 May 2015 06:09

24:45.626S  152:23.138E 

 

Twenty four hours later we left under grey skies and with a strong swell coming in the mouth of the Burnett River.  Unfortunately, as we left the dock we both noticed an unpleasant whine coming from somewhere in the region of the engine, or perhaps the gear box or maybe the shaft driving the propeller.  As we headed down the channel we tried several engine and gear moves to try to ease the noise or identify what might be the problem.  After a couple of miles we had no answers so turned around and anchored in the relative shelter of the river while we went below to investigate.  Each likely source was checked then tried in gear and out of gear and all the oil levels checked.  Nothing.  We did identify that the problem did not exist when in reverse only in low revs going forward.  Clearly something we could not proceed with, so sadly we made our way back to the marina berth we had just left.  Although it was Sunday I telephoned the Yanmar engineer, Gary Dann, and left a message asking him to call me on Monday morning.  To his utmost credit he rang me back almost immediately and said he would come and see us at 0700 on Monday.  On the dot he was there and listening to the noise thought it was the alignment of the engine and shaft causing the whine but in order to check and correct this we needed to remove the flexible coupling and the rope cutter in front of the propeller.  The boatyard were brilliant and lifted us out immediately and we had an hour with Tashi Delek sitting in the slings on the lift while we remove the flexible coupling and the rope cutter to re-set the prop shaft and then re-assembled the rope cutter.

 

The flexible coupling

The damper disc comes out

 

Back in the water, the alignment was checked and the engine run in gear.  The whine was less, but not gone, while the back of the engine and gear box were vibrating as badly as before.  So the shaft and gear box were disconnected again and the Damper disc removed (this is the bit between the gear box and the engine which takes up the pressure when the yacht is put in gear).  It was rusty and worn and the springs were loose, but this was reasonable wear and tear really while nothing was obviously broken or wrong.  Anyway we ordered a new Damper disc which was delivered and fitted in 24 hours.  When the engine was run in gear the whine and rattle were gone but the gear box was vibrating as badly as ever.

 

 

The old Damper Disc – rusty with rattling springs

The new one goes in…….

 

Gary sought a second opinion from an expert on shafts and propellers who was satisfied that it was nothing to do with the propeller, the shaft or any of the seals along the way to the gear box.  The engine was running extremely well and the new damper plate was now taking the strain perfectly.  There was nothing for it but to remove the whole gear box and look inside.  This was a grave concern because these gear boxes are very well designed and manufactured and supposed to be indestructible.

 

 

The gear box now in the workshop

Are these the offending parts?

 

Sadly nothing is obvious and the only thing Gary could find were two worn discs which press on the flat springs which push the main cone into the gears.

 

Note the deep groove – it is supposed to be flat.

Or is the bronze cone the offending part?

 

New rings and springs were delivered in 24 hours, the gear box re-assembled and fitted back in the boat.  When the engine was run in low revs forward the vibration was as bad as before and no amount of adjusting the gear lever or the couplings made any difference.  By now it was Thursday evening and Gary was deeply concerned at not solving the issue and finding himself with a problem he had never experienced before and which had no clearly identifiable cause.

 

On Friday morning we discussed our only two options with Gary.  A new bronze cone which might solve the vibration would cost A$1000, have to be ordered from Singapore and would take 7 to 10 days to get to Bundaberg, while a complete new gear box was available in Melbourne for A$3000 and was only 4 days away.  Bearing in mind his doubts over the cause of our problem, that we have a long way to go to Singapore, with no support once we leave Australia or through Indonesia, we reluctantly ordered the new gear box, which it was promised would be in Bundaberg by Tuesday.  To be continued ……………..