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coupler keeps breakin.......getting expensive

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Patt

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I have a 4.3 mercrusier and the coupler keeps burning out. I had it replaced and it did the exact same thing. The transom is solid and the machanic assures me the alignment is perfect. He is telling me now that my prop is my cause and I dont belive this to be correct. I've talked directly with stigray boats and they tell me the prop I have is the write one. Does any one have any suggestions:confused::confused::confused:
 
post a picture of the damage ... boat size ? prop size ? what type drive ? model year ? exactly what got " BURNED UP" ? THIS CATCH ON FIRE ?
 
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check the oil in the outdrive - have a look at the upper gears and bearings. The drive maybe seizing up.

if nothing of concern found there, watch the engine while someone else drives, see if the mounts are moving or the hull is flexing.
 
The boat is a 20'3" stingray 4.3 liter with a alpa one drive. The coupler goes after running the boat for an hour or so, then, in each case I was trying to plane out pulling a tube and at about 3500 rpm it spins out and the smell of burnt rubber and smoke coming from the engine compartment. the boat has a quicksilver 21 prop. The first time we replaced the coupler we looked at the gears and bearings and also changed all the fluids in the motor and lower unit. Every thing looks fine here, but we wont have the motor out untell tomorrow for a second go round
 
3500 rpm is about where a 4.3 makes maximum torque.....

did you personally see the fluid coming out of the drive? I'd be looking closely at it.

does the boat seem to be labouring more than normal just an instant before it fails?

hours on this boat? has it been doing it since new?
 
so this is the second coupler. with a rapid failure. I would suspect improper alignment or drive problems/gimbal bearing..

post the results and picture if possible...also how did the damage look this time compared to the last time ?


21inch pitch prop is a little on the high side , but not that much to do this damage or any damage.
 
I feel ur pain. In the 3 years I have owned my boat 99 Fisher avenger sport 19 4.3 liter Alpha 1 gen 2 running a 4 blade 21 pitch prop. I have had 2 coupler failures, 1 soon to fail coupler, And when I bought the boat the coupler was just replaced. Shop where I bought the boat has been good about warranty work. Cause unknown to them. They found a bad motor mount on last failure so I`m hoping that`s the cure. Makes it hard to run very far from the dock especially on big water.
 
Thank you guys for all your input. I did not see the fluids come out myself. The rubber in the coupler burned up the first time and melted it and it acually fused itself back. The motor is coming back out today and Im goan be there this time, my machanic is a neighbor. I was thinkin maby I have a bad motor mount. The boat has about 450 hrs on it and yes it seems to labour some just befor it goes. I talked with the original owner wich Im the second and said he never had any mecanical issues with the boat and he put the quicksilver 21 prop on 9 years ago. The boat is a 94 stingray 609zpx(cuddy)
 
Just a thought, My trim switch needs replaced and the the trim limt switch is probaly bad as well, if I was under way and trimmed it to high by the trailor switch could this cause something like this to happen??
 
if the trim was up too high normally you would get noise from the rear of the boat with this position. this puts stress on the gimbal beaing and the u joints ..its best to have the indicator repaired. since the engine is coming out do it..

with your engine and boat load the drive should be 95% down ..
 
On most boats, the prop would be ventilating long before the drive was tilted up enough to cause damage. I suppose on takeoff, if you had it right up, but I think you'd be hearing world war 3 in the gimbal housing.
 
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thank all of you for your sugestions, were pullin the motor now and I'm applying all the sugestions I've recived. Once we get it out and tested I will let you all know the verdict. Thank you again!!!

Patt
 
hi patt had a boat that had the same problem,buddy put one in the first time burned up about 30 mins damn gotta do it again,this time took it to a merc dealer they had to align the motor with a couple washers, that is what the align tool needed to slide in out with ease! the mechanic also told me u have to break it in low speed and do not pull anything for the i think he said 1-2 hour, i think thats right been a long time ago, when u take it back ask about the break in period. hope this helps good luck!!
 
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