Rusty Bolts & Removal of Old Stern Gland-How to?

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sailingjupiter

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Following my last post about which shaft seal to go for, I have decided to see if I can remove whats there already first. Its an old stern gland. Will this come apart easily?

There is also the coupling that holds the shaft in place with 4 allen key bolts. I assume these have never moved in the 18 years of the boats life and look well rusted. Any tips on how to get these out. I have read about releasing oil and hitting it with a big hammer!! Obviously I don't want to damge anything. Anyone had a similar problem? how did you undo the things?

Assuming I do get it off would the prop shaft just slide forward so I can put on the new shaft seal and then just reconnect up? New bolts will probably be a good idea. What type, stainless, galvanised etc etc. Engine is a Yanmar 1GM10.

Thanks again for the help.
 
The four socket-head cap screws clamping the Yanmar flange to the forward end of the shaft will benefit from a good squirt or two of WD40 or similar and then leaving between squirts for 1/2 hour to soak in. Then with a good quality new allen key tap (hammer) the short end of the key into the hex recess and apply a short length (6 inches) of steel tubing (water pipe, conduit or similar) to the long end of the key and it should undo with a fair amount of force applied. If still seized, arrange a sheet of metal (eg scrap corrugated iron) to protect the nearby hull and carefully apply heat from a propane torch to the flange in the area where the screws are located. Allow to cool, apply more WD 40 and try again.

When the flange is off, you can draw the propshaft out of the sterngland aftwards, provided there is room between the prop and whatever is aft of it. Otherwise, you can dismantle the sterngland and draw it forwards over the end of the shaft
 
I faced a similar problem a few weeks ago - also a 1GM10, also rusted allen headed bolts.

The forward two came away surprisingly easily given their appearance but the back two had no intention of moving - may have had something to do with being dreached in brine.

The problem is really that one your allen key or socket bit slips the socket in the bolt becomes rounded and you have really lost the game. I ended up cutting the bolts and then trying to drill out the bolts - bad move - they are VERY hard and its all but impossible to drill straight and then clean up the threads.

Result - I bought a new coupling from ASAP - with the external bolts and nuts this time.

(Trying to do all this standing on your head, upside down in the quarter berth just adds to the thrill of boat owning /forums/images/graemlins/confused.gif)
 
I doubt you will be able to slide the shaft forward unless the engine is out of the way. You may have to slide the shaft backward if you can get it past the rudder, this might mean removing the prop or dropping the rudder. You will need to get the shaft out of the hub, If you manage to seperate the flange from the hub which holds the shaft you may find there is a large nut on the end of the shaft inside the hub. Also there may be a set screw held with a locking nut through the hub onto the shaft.
Shafts are notoriously difficult to remove from the hubs. If you find it stuck there are various methods for removing it. If you do get it out you should be able to slide it back, undo the fixings from the stern gland to the stern gland tube on the hull then the whole assembly should be able to be slid forward along and off the shaft if you have enough room.
Good luck
 
I bought some allen key sockets for my socket set. Mine were a similar age but came undone with a bit of effort and no hammer.

You will find it easier to partially undo the bolts that hold the shaft in first so that you can apply some pressure which you can't if you undo the coupling from the gear box first.

The coupling may well have either an allen key grub screw into a hole in the shaft or some have roll pins that need driving out (long driving pin/punch set cheap from Machine Mart). If roll pins then don't drive the right out as they are a b---------- to get back in. You can see my allen key grub here
shaftseal.jpg


If you have a P-bracket then before you move the shaft back make sure that you have cleaned the bit outside the boat or you will damage the cutless bearing.

One the coupling is off and the shaft out the rest is easy. You shouldn't need new bolts as they are SS.

Good luck
 
If you get problems with rounded off heads these grip like nothing else - left hand coarse thread inside that will grip good and knackered heads.

If you need to know the outside sizes of the sockets for clearance drop me a PM and I'll pop down to the workshop and measure my set.
 
The trick with elderly Allen bolts is to make sure that the key goes right to the bottom of the socket. Scrape out any debris, rust, etc. with a sharp tool before offering the key up.

Be careful with hammering - all the impact is being resisted by the gearbox bearing, which will not be improved by this action.

As others have said, a long lever is the answer provided that the key stays in the socket. If these are black bolts they will be hardened and should not round off. Ensure that the Allen keys are good quality ones - plenty are sold these days that are painted black to look like heat-treated ones. Test yours by trying to cut them with a hacksaw, if they cut they are no good.

The technique I use is to set up two allen keys, one each side of the flange, one resisting the leverage of the other. One can rest against the hull or something else, giving the option of two hands on the long lever. Otherwise, use a bar wedged between the bolt heads, other end on the hull. Protect the hull with a piece of wood.
 
Don't despair if you can't get the coupling off. Getting a new shaft machined is cheaper than you might think.

I'm probably going down this route after much skinned knuckles and bad language as I try to get the green Swedish monster out of it's lair beneath the companionway.
 
I'll chuck in my two penn'orth!

Hex keys [Allen keys] come in metric and imperial sizes. Make sure you use whichever fits perfectly. Don't economise on them; cheapies off a market stall will fit badly and round off when used. Apply PlusGas a few times [obtainable from car accessory shops etc] to the bolts and let it have time to soak in.
 
A second vote for the "Irwin extractors". Just pick the correct size and tap it on with a hammer and away you go.

All this talk of using a hammer and no one has mentioned the need to have a heavy weight on the opposite side of what you are hammering. Just hammering the coupling will do SFA but hold a heavy weight on the oposite side of the coupling then hit the couplng will reduce the risk of damage and help "shock" the siezed stud or shaft free.

PlusGas vs WD40? I've found PlusGas to be more effective.

Tom
 
Hello Springjupiter

May I be as bold as to throw my hat into this ring. I would tend to tackle the problem from a slightly different angle, with good reason.

I agree with all that has been said about WD40, penetrating oil and heat. All are good points.

Thoroughly cleaning out the Allen socket is also very good and I also agree with that point.

Where I differ is, whereas everyone seems to suggest going with Allen Keys with or without a lever extension bar (tube). As the area is so confined and you stated you are upside down in a ¼-berth this is asking a lot and remaining safe. Allen Keys are high tensile steel and in the past, I have used a steel tube to increase torque and the Allen Key has shattered.

What usually happens when they shatter is that your hand whistles round and you leave knuckle skin on sharp items that get in the way and it is VERY painful.

I would like to suggest an new method. Use an Allen 'Hex' socket (metric or Imperial to fit) and use a 10 inch ½"-drive 'T'-bar to apply torque.

http://www.screwfix.com/prods/18011/Hand...t-7Pc-3-8-Drive

http://www.screwfix.com/prods/13154/Hand...t-Set-5Pc-Drive

To make sure the Allen socket remains inside the recalcitrant bolt you need to hold it in place gently. To accomplish this you use a 4" 'G'-clamp which you nip up only to hold the socket and 'T'-bar in place. You now have no worry of the socket jumping out of the bolt as you apply pressure.

Like tapping a new thread in fresh metal, you work the 'T'-bar backwards and forwards about 20º to 30º at a time and keep adding lubricating oil and in a few moments the bolt should free and you will be able to remove it successfully.

The 'G'-clamp is only to make sure the socket does not climb out of the bolt, I usually use a 4" Record clamp. If the problem was very small bolt, I have used very large Mole Grips and a ¼-'drive socket set.

Good luck. /forums/images/graemlins/smile.gif
 
Lenseman that is exactly the technique I use. So far, on incredibly stubborn flywheel bolts and other instances, it has been completely successful. It also has the big additional advantage that, when replacing the bolts, you can use a torque wrench to apply the correct loading.

Your idea of using a small cramp/mole-grips to hold the the socket in place is excellent and would certainly have the benefits you descibe. /forums/images/graemlins/smile.gif
 
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