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-   -   tail shaft - how much wiggle? (https://www.moyermarineforum.com/forums/showthread.php?t=10732)

Peter 06-02-2018 06:12 AM

tail shaft - how much wiggle?
 
Hello all,

I had a leak at the rear of my reversing gear and am tackling the repair this year. So far I have lifted my engine forward into the "salon" and removed the output coupling and thrust bearing.

The spring was broken in the oil seal so I am hoping that was the root of the problem.

while i am in there i decided to replace the thrust bearing as well.

My questions.

1) Should there be any side-to-side play in the tail shaft with the output coupling removed? Mine has a fair bit of wiggle - maybe 1/4" or 3/8"?

2) Would this suggest a bum pilot bearing?

3) If so, can i remove the reversing gear with the thrust bearing plate removed?

4) Is this all covered in the reversing gear video?

Looking forward to your wise council.

Best,

Peter

Al Schober 06-02-2018 09:02 PM

The output coupling rides inside the rear bearing. With the coupling removed, the tailshaft will have some motion - can't really say whether 1/4" is too much. Check again with the coupling in place - should be fine.
Replacing the seal should stop the leak. First overhaul I did consisted of new rings and a new output seal. Engine is still in the boat to this day, and just completed a run from CT to Rockland, ME - including about 30 hr of continuous running (at reduced throttle, burning 10 gal of fuel). Only issue was an exhaust system failure, repaired class A in 9 hours at Burr Bros in Marion, MA.(yes, this is a plug - they're good and fast).

Peter 06-07-2018 07:09 AM

To close the loop on this, I examined the tail shaft on a blown engine I have kept for miscellaneous parts and trying out repair procedures on.

The tail shaft on that engine wiggled about the same as the one in the boat.

I concluded that is the normal amount of wiggle. I suppose they both could be bad too...

I finished the repair and cannot recommend the MMI Tech Video on rear seal replacement highly enough.

Transmission seems to work fine now - no leaks and much quieter with the new thrust bearing.

Regards,

Peter


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