How to remove rusted strut bolts ('81 33)

[Rabe]

I was looking at the propeller shaft strut bolts underneath the cockpit and they are extremely rusty.

An angle grinder won't fit in the area.

Anyone have any ideas how I can remove these?

Best regards,

Rick

 

[Tally Ho]

Be careful…re-aligning a strut is reportedly a tough job ( I haven’t done it).


Greg

 

[sandpiper10471]

I remember those. Mine weren't too bad, but then she was only about 10 years old when I bought her. Possibility - drill the heads out from the outside and remove the strut, then punch the remaining bolts up inside or with an extension, turn them until free and removed.

 

[kloudie1]

Nut splitter? (ouch)
Amazon.com: Cal-Hawk Tools Nut Splitter Tools - 2-Pc. Set : Tools & Home Improvement

 

[Ralph Johnstone]

My first try would be to remove the nuts and grab the bolts from the inside with a vice grip and try working them out of the holes down through the strut.

If they're bolts with protruding hex heads, you may be able to worry them to death with a Dremel grinder (they're small but low powered). If they're flat head machine screws (like mine) time to kiss the strut goodbye.

Looking further into this, is there really any advantage at all in removing the bolt heads ? If you can't force them downwards it's doubtful you'll get them going upwards either. Mind you, desperate times call for desperate measures.

Pay particular attention to @Tally Ho 's comment in post #2. If it were me, I'd be looking at removing the strut to reseal the area under the strut once the bolts were out. Too much chance of leakage if the sealant under the strut breaks. If you destroy the original strut, re-alignment with a new strut will be difficult requiring new holes.

Lots of thought and planning ahead. Best of luck and let us know how it goes.

 

[Rabe]

Be careful…re-aligning a strut is reportedly a tough job ( I haven’t done it).

Absolutely is a tedious job. But entirely doable with shims and several attempts.

Possibility - drill the heads out from the outside and remove the strut, then punch the remaining bolts up inside or with an extension, turn them until free and removed.

Will look into this idea. Might be that the drill can't align straight on the heads. We'll see.

Nut splitter? (ouch)

Maybe.... I'll have to look closer and see if it'll do the job or make things worse... Everything is so rusty inside...

My first try would be to remove the nuts and grab the bolts from the inside with a vice grip and try working them out of the holes down through the strut.

If I can remove the nut and/or cut off the bolt inside Working the strut down and off the boat should pull the remaining bolt length through the holes. At least that's what I think should happen.

If they're bolts with protruding hex heads, you may be able to worry them to death with a Dremel grinder (they're small but low powered). If they're flat head machine screws (like mine) time to kiss the strut goodbye.

I believe they are hex bolts sunk into the strut. But I don't follow.. Why would I have to kiss the strut goodbye if they're flat head?

Looking further into this, is there really any advantage at all in removing the bolt heads ? If you can't force them downwards it's doubtful you'll get them going upwards either. Mind you, desperate times call for desperate measures.

I'm thinking that the removal job will be a cake walk if either the nut is removed, bolt & nut is cut off inside, or if the bolt head is drilled out or removed.

Lots of thought and planning ahead. Best of luck and let us know how it goes.

Definitely in the thinking stage. Having the yard do all this is on the table as well.

 

[Ralph Johnstone]

I believe they are hex bolts sunk into the strut. But I don't follow.. Why would I have to kiss the strut goodbye if they're flat head?

If they are flathead machine screws, I can see the grinding doing damage within the countersink.. I can just see part of the strut base going with it unless you're super careful, and very religious.

If I can remove the nut and/or cut off the bolt inside Working the strut down and off the boat should pull the remaining bolt length through the holes. At least that's what I think should happen.

I suspect there's sealant under the base which will not be pleasant. That'll require a whole new vocabulary to remove the strut, unless the sealant is deteriorated to the point where it'll let go easily.

Having the yard do all this is on the table as well.

You seem pretty comfortable with this type of work so I would not approach the yard until absolutely everything else has failed. I have seen too many of these guys bulldozing through a job in an honest and sincere attempt to avoid spending endless hours ($ $ $ $) doing what should have been a simple job. You may be looking at some really time consuming crap with this but in the end, it'll give you the results you want.

 

[heritage]

I removed and replaced the prop strut on my 84" H27 which probably has the same strut and bolts as yours. The bolts are 1/4" flat phillips head. After removing the nuts, I was able to drop the strut by sinking an old chisel between the strut and hull. After cleaning up old caulking off the strut and fairing out the strut seating area on the boat, I laid in a thick bed of thickened epoxy to re-seat the strut in. The wet epoxy bed allowed me to align the strut with the prop, then secure the assembly with a couple of boards from the ground to keep it aligned until the epoxy set. It was a two man job to put the bolts back in.

You might try putting vice grips on one of your rusted nuts and turning the bolt from below with a large screw driver or impact driver.

 

[Rabe]

You seem pretty comfortable with this type of work so I would not approach the yard until absolutely everything else has failed.

Exactly

 

[RoyS]

The two nuts should be accessible inside. If you completely remove the strut you may have considerable difficulty realigning and sealing underneath it. If you go that route (and I do not advise that) you must keep the prop shaft centered in the stern tube and turning freely in the cutlas bearing. Leave the trans in neutral and you can tell if the shaft is binding in the bearing by turning the shaft by hand while observing the shaft alignment (centered) in the stern tube. Are you sure you need to do this? New flathead screws can be found at McMaster Carr.

 

[Rabe]

The two nuts should be accessible inside. If you completely remove the strut you may have considerable difficulty realigning and sealing underneath it. If you go that route (and I do not advise that) you must keep the prop shaft centered in the stern tube and turning freely in the cutlas bearing. Leave the trans in neutral and you can tell if the shaft is binding in the bearing by turning the shaft by hand while observing the shaft alignment (centered) in the stern tube. Are you sure you need to do this? New flathead screws can be found at McMaster Carr.

Am I sure I need to remove the rusty bolts - absolutely. Unless this shouldn't be a concern???

Am I sure I need to rebed the strut? Not really but probably.

I had the survey for insurance and one of the items is that the prop might be misaligned. On the back side of the shaft, you can see a small gap while on the front side there is no gap. The size on the back side? I don't know really, but if I had to guess - about a 10th to a quarter of a mm.

The real deal for me is to replace the bolts. They are really bad off.

 

[Ralph Johnstone]

Am I sure I need to remove the rusty bolts - absolutely. Unless this shouldn't be a concern???

Not a problem ........................... until they start to fail and all hell breaks loose in the most inconvenient location imaginable ! ! ! !

From what you've described with the state of corrosion, they sound as if they may be steel ? ? ?

Didn't you mention that you may have a bit of an alignment problem before you even get started. I can see it's going to be a looooooooong winter ! Best of luck.

 

[DianaOfBurlington]

Be careful… re-aligning a strut is reportedly a tough job ( I haven’t done it).

Greg

Be careful… re-aligning a strut IS a tough job ( I HAVE done it!).

 

[RoyS]

You might try applying a magnet to the screws to determine if they are stainless or plain steel. Assuming they are stainless you may be able to leave them alone. Only you can see them and determine that. Then tackle your alignment problem by adjusting your motor mounts as needed. Long winter no matter how you look at it.

 

[Rabe]

Then tackle your alignment problem by adjusting your motor mounts as needed. Long winter no matter how you look at it.

It appears that when the cutlass bearing was replaced the PO dropped the strut instead of the rudder.

I believe when they put it back they didn't bother looking at the alignment of the strut.

Don't you think shimming the strut will the most direct method of correcting the alignment?

 

[Ralph Johnstone]

Don't you think shimming the strut will the most direct method of correcting the alignment?

As long as you can get a good load of sealant in there.

 

[tmjb]

I have an ‘81 H36 on which I replaced the bolts (flathead machine screws) realigned and reset the strut because it was loose when I got it.

My strut was bronze and the screws attaching it to the hull were bronze also. If your strut is also bronze but the bolts/screws are steel or stainless steel I would replace them because of the corrosion that will have taken place due to the sacrificial loss of the steel/stainless steel due to electrolysis.

I found the realignment of the strut tricky but not impossible with some care. There is a thread that I found on the forum about it that was helpful. If I can find it I will send a link to it.

Good luck.

 

[RoyS]

The single unmovable component in this alignment is the stern tube. Everything else must align with the stern tube. The prop shaft should be checked for straightness before beginning. There are different ways to proceed, here is one: If the strut is definitely is out of place then remove it. I would initially adjust the motor mounts with the shaft connected to result in the shaft passing through the stern tube centered, checking inside and outside. You can do this by eye. Tighten the motor mounts. With the transmission in neutral so that you can rotate the shaft by hand from outside, apply your preferred sealant (an important subject needing further discussion) and insert the fasteners. Have someone else turn the nuts down from inside the hull. While you are outside holding the screws from turning, rotate the shaft to ensure there is no binding in the strut bearing and that the shaft remains centered in the stern tube. This is not the time to significantly tighten the nuts. When the shaft is freely rotating, the sealant is completely filling the contact surfaces, and the nuts are equally supporting the strut, stop. Wait for the sealant to completely set. Then tighten the strut nuts snugly while holding the screws from turning. If all went well the shaft should freely turn in the strut and the shaft should still be centered in the stern tube. The selection of sealant is no small matter and I leave that open for further discussion.

 

[Rabe]

Took some pictures this weekend while I was working on the boat this weekend. I didn't notice, but the front of the strut image isn't all that great. It should show a smaller gap under the shaft and an larger gap above.

 

[Jim Legere]

I removed and rebedded the strut on my H37C years ago. I think you might have success getting the nuts off the machine screws (bolts) that hold your strut on. Clean out the area as best you can - shop vac, wire brush, etc. - and then hit the nuts with PB Blaster (or similar) a couple of times and let it soak in for a couple of hours. Then get a 6-point deep socket to fit the nuts (9/16"?) with a suitable extension and ratchet. Have a friend hold a large Phillips screw driver on the screw heads below while you apply torque. With a bit of luck you'll have the strut out within half an hour. Heating the strut with a heat gun or judiciously with a torch can help break the bond of the bedding material (sealant). Its something like 3M 4200 or 5200.