Mercruiser Engine Coupler Failure -- How long do they last question

[Maclin]

I am getting the engine ready to remove and found a clue that may point to the reason the coupler failed. When I looked closer at the top mounting nut on the forward mounts as I began to remove the lags it did not look right. I grabbed it and it was finger tight on the left side and was just above the lock washer on the right side. I am so disappointed that I did not at least touch all that when I was looking it over pre-purchase. This boat has tall freeboard and the caverns back there are too deep for me to reach anything unless I take the seatback out first, but I had it out to do the filter and could have discovered this before it failed, grrrrr.

Who knows who or what got interrupted that led to the top nuts not being tightened into the lock washer, sigh.

So, with the engine being able to move up some each time the boat grabbed air and came down hard was affecting the coupler. Probably.

I will start a new thread if I run into any problems with the alignment.

Later....

 

[nola mike]

I'm on 31 years so far. Checking alignment is great, but really it shouldn't ever be off unless something else is going on

 

[Maclin]

Yeah, I am a little concerned about the previous attempt at alignment that seems to have been interrupted, or otherwise not completed. Lags were in solid, no structure is compressed or compromised it appears. As the Zen master would say, "We'll see".

 

[Scottyd2002]

I wonder if running too low rpm due to incorrect prop size would cause coupler failure?
the 4.3 V6 is only maxed out at 2200 RPMs seems way too low?