propeller shaft support strut

[jibseaman]

My strut is loose and leaking seawater. while clearing the prop of crab pots I discovered that the support strut could be moved more than an inch from side to side. I have vibrations and am leaking sea water. I am hauling the boat in two days and would like any info that will help me know how and what to do to correct this. The transmission is also making a high pitched noise in fwd gear, is this normal? I suspect it could be a thrust bearing going bad. The boat is new to me but the previous owner said "it always sounds that way, don't worry". so I do.
Thanks for any help

 

[Don S/V ILLusion]

As you should (worry). It is amazing what someone will say just to sell a boat without regard to the new owner's safety.

It is possible the vibration and misalignment caused by the loose strut could create sufficient stress on the transmission as the shaft cannot turn freely and result in the whining you described. Transmissions in boats are not designed like those in cars and don't like loads.

It sounds like you will be replacing the strut and it's bearing so make sure the shaft is properly aligned AFTER she is back in the water before testing.

You might also send the PO a note telling him how proud his parents would be with his concern for your safety.

 

[jibseaman]

the transmission does not make this high pitched sound when in reverse. I know I will learn more when she is out of the water and I wonder if I need transmission work or replacement?

 

[Claude L.-Auger]

As Dan said the whining may be caused by the loose strut and obvious misalignment. You might not need to replace the strut itself once you find out why it is loose. Find the cause, fix the problem, re-install the strut if not bent and replace the cutless bearing. It will be easier to install the new cutlass bearing on a press when the strut is removed.

Since you mention leakage, you might want to replace the packing gland as it has probably suffered from the misalignment and vibration of the shaft. Easier and less worry when doing with boat out of the water.

After strut and shaft are reinstalled and bolted on the tranny, with engine in neutral make sure the shaft is turning freely. Once in the water, check engine/shaft alignment. Chances are with the problem you're describing you will need to re-align.

Don't know if it's the same on your boat, but on mine I can take tranny out without touching the engine. If it's the case, I would try the boat and see if tranny is operating correctly without that whining noise. PO being careless enough to tolerate such a problem, I would change the oil in the tranny before using the boat, or at least check the level.

You don't specify the make of engine or model of tranny, but if you need to, there is an excellent shop in the Fort Lauderdale area. I believe it's called Marine Transmission Service.

Good Luck

 

[jibseaman]

Thanks for that. here's a little more info.
yanmar 15 hp that came with boat trany unknown. The leak is coming from the strut through bolts (there are two of them) They were loose so I tightened them and slowed down the leak. I changed the oil in engine and trany, PO used 40wt motor oil in trany. I read my engine manual and it says to use ATF so I did is this correct?

 

[Claude L.-Auger]

Yanmar has 2 types of tranny, one that uses same oil as engine and other uses ATF. Be absolutely sure of which is which before running the engine/tranny. Take a look at picture and see if you can locate the markings on your tranny. It should be located at the 12 o'clock position on the tranny when looking at it from the shaft side. Once you indentify which one you have, then the Yanmar book will let you know which oil to use. If you got the wrong oil in it then you'll need to syphon it off and replace with the proper one.

As for the strut bolts, when the boat is out of the water, loosen them and rebed the strut after inspecting the strut (if straight) and changing the cutlass bearing. If bent, then replace with new one. Working on the strut is a 2-men job as one has to be under the boat to keep a large screwdriver on the head of the machine screw and the other one is inside tightening. Do it in sequence so the struts sits properly.

Good luck

 

[jtm]

strut

Hi Claude-

you might find that 2 or more of the 4 strut bolts have been eaten away with crevice corrosion- I pulled mine about 4 years ago after seeing some spotting around the shaft. 2 or 3 of the bolt shafts- were half eaten away- find good quality replacements and a little 3M 4200 to rebed the strut/bolts- I suspect that with the amount of strut play you have, you may also need a new cutlass bearing. alignment issues may cause the noise you hear and might go away with a properly seated strut- thing is,.... you can know for sure about the alignment until the hull is back in the water for a week or two and takes its "natural" set in the water... rather than the stresses on the cradle or pads.

 

[jibseaman]

so heres what i found.

here it is, the strut bolt were loose and came off by hand. The area under the strut had been filled before with a hard filler that cracked and fell apart. The stainless shaft looked good and strait so I will replace the cutless bearing and re-mount the shaft. I plan to build up the area with something (need some help here) then slide the strut on the shaft and put it lightly in place. I will use wax paper between the strut and boat also teflon tape on the bolts. hopefully when it hardens i can remove it and then fasten it in with another sealant (what kind)?

Thanks for your thoughts

jibseamon

 

[SamLust]

Your strut/shaft/stern tube/engine assembly MUST all be installed and lined up properly together. Not hard but MUST be done. Expect to have to raise the engine about 3/4 inch to get it right. I have posten on this numerous times. Check the archives and see if you can fine the post. If not PM me and I'll re-post. I may even have pictures.

 

[jibseaman]

thanks Sam, turns out the engine mounts are also shot. I am having trouble pulling the shaft out, any suggestions?

 

[SamLust]

If it's the coupling you use the coupling itself as a press by placing a socket or spacer inside against the shaft and bolting down. If the rudder is the problem it has to come out. Mine required a hole about a foot deep. It was in my own yard so the only complaint I got was from the Admiral. Pulling the rudder will give you an opportunity to replace the rudder tube packing nut which if it is original is almost rusted away.