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Discussion Starter · #1 ·
Hello!

The boat in question is a 2007 Hunter 38, equipped with a Yanmar 3JH4E engine and Kanzaki KM35P gearbox. The boat has been on the hard for two years , almost 3 now due to covid travel restrictions. I replaced the unknown age PSS shaft seal that was on it (it looked old and started spraying some water on our last season).

While doing the replacement, another shaft coupling was required (used R&D split coupling) machined to my shaft size, and it was faced at a local machine shop.

Everything was going fine, alot of learning and time lost, but i was going somewhere! hehe.

Upon installing, I noticed the propeller shaft is sitting low in the stern tube, it was probably this way before, but it is causing the PSS carbon rotor to rub on the shaft once compressed. Does not look safe.. I tried various bellow angle but no luck. I compared the new kit vs the old, and the ID of the new carbon is slightly smaller (about .05", maybe enough to cause an issue. The only solution I am coming with, is to raise the engine in order to allow the shaft to be more centered in the stern tube.

The mounts look like the original ones, I tried prying them and they do not look unglued/broken/damaged. I know it would be good practice to replace them, but budjet is getting tight. Can the engine be raised, about 1/8" to 1/4" without issues with shaft&coupling alignment? I took the time to mock up a setup with the shaft in a raised position, and at the cutless bearing clearances suggest it would not bind or be in too much of an angle.


Quick sketch
Handwriting Signature Rectangle Font Writing


View of stern tube, shaft being low, it's centered left to right, dont worry!

Automotive tire Hood Automotive exterior Bumper Composite material


Engine mount current position (port side are slightly higher than starbord)

Nickel Gas Household hardware Engineering Gear


View of starboard/stern mount (access is the easiest, gives an little idea of the condition)

Motor vehicle Automotive tire Rim Gas Automotive wheel system


Am I being foolish?

Thanks for your time!!
 

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Yes, engine needs to be raised. Look up the procedure for aligning an engine as it's very precise and uses feeler gauges between coupling and transmission flange. You will have to recheck / redo the alignment once the boat has been in the water a week or 2, but doing it on the hard should get you in the ball park and make it easy to ensure the shaft is centered.
 

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I would use something like small wooden wedges, at least three of them, and get the shaft centered in the shaft log leave the bellow and seal collars fwd until you get everything lined up, bellow is not designed or made to hold the shaft in the center that is held in the center by the proper alignment which you still have to do as mentioned

good luck I had on Oday 30
 
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I have been through something like this with my Hunter 36 when I had the stuffing box replaced. But I had the boatyard workers doing it not me. After a few different things that didn't work, they did move the engine - I can't remember whether it was up or down - and then re-aligned it. They do insist that 2-3 days in the water is needed before doing the final alignment.
 

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Discussion Starter · #6 ·
I feel it is unlikely the alignment changed much except for flex while on the stands. I think you should wait to see what happens when you are back in the water.
It was my first tought, but in it's normal position, I can move the carbon rotor left, right, downward, but never upwards, which suggest it's rubbing against the propeller shaft. It's not designed to be used this way, it may score the shaft, but worst, could overheat and cause catastrophic failure.

Thanks everyone for your imput, it's always gladly appreciated!

I managed to found the min/max height mount settings in a yanmar installation guide, too bad i'm home and cant confirm if I am in the safe zone.. Knowing how old the mounts are, but still look in decent shape, would you replace them?
 

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Hello!

The boat in question is a 2007 Hunter 38, equipped with a Yanmar 3JH4E engine and Kanzaki KM35P gearbox. The boat has been on the hard for two years , almost 3 now due to covid travel restrictions. I replaced the unknown age PSS shaft seal that was on it (it looked old and started spraying some water on our last season).
I just replaced my shaft, coupler, and seal, and had the same experience.... The old setup seemed to be perfectly in line, but with the new parts, I had to raise all 4 corners to get it lined up again... Doesn't seem logical, but it happened...
 

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Discussion Starter · #8 ·
I just replaced my shaft, coupler, and seal, and had the same experience.... The old setup seemed to be perfectly in line, but with the new parts, I had to raise all 4 corners to get it lined up again... Doesn't seem logical, but it happened...
It reassures me that i'm not crazy hehe
have you had issues with the mount studs being in a higher position? (more stress)
 
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