Beta 20 gearbox to prop problem

[destroyer28a]

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Hi i have just bought a boat and have some trouble with the gearbox apparently not selecting gear, but what it actually is seems to be a coupler that goes from the gearbox and the holds the prop shaft, this seems to be spinning about, occasionally it will lock and i can select fwd and get drive, but as soon as i go astern it seems to pop out, and a lot of noises happens and i lose all drive both ahead and astern. Trouble is i dont know what this "spinning" component is called so cant price it up and dont know if the job is doable or do i need a marine specialist to remove the engine?

so my question is what is the bit i need to fix called?

thanks in advance.

 

[Tranona]

That sounds like the half coupling on the shaft. It is probably clamped to the shaft with two allen screws that have come loose allowing the shaft to slip. May respond to tightening, but may also have worn the shaft. Try tightening them first.

 

[webcraft]

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Might be a flexible coupling. I doubt if you need a new part - just take a photograph and/or do an exploratory partial disassembley and get back to us.

- W

 

[destroyer28a]

Thanks for the replys, i do remember seeing some bolts on a coupler, i will look tonight and take some pictures.

 

[destroyer28a]

Hi again, i have been to the boat and examined the part in question, I have posted a picture as well. If i look at part B in the picture it is spinning on the shaft, i take it the 4 bolts can be tightened to cure this, if it doesnt then i guess its a new shaft? Also part A in the picture, is this the Stern gland and the 2 screws either side, do they tighten to pack more grease in? and to repack it with grease does the boat need to be out of the water? I had someone look at this and they have quoted £600 i wonder why they have said this if its only the 4 bolts, also they told me the shaft could fall out of the boat and it will sink is this right? And last question should i be able to spin the shaft by hand? oh and will it be ok to undo the 4 bolts on part B to examine the end of the shaft. Thanks again.

 

[30boat]

The coupling besides being too rusty(showing neglect) may be loose.You can try and tighten the bolts and see if then you get grip.I would replace the bolts with new ones.If the shaft slides out of the boat you can indeed sink but the incoming flow of water can be easily(ish) stemmed by stuffing the hole with rags or tapping in a conical softwood bung.You can buy these in chandlers and it is wise to keep several in different sizes onboard.The shaft may have worn beyond repair if it's been doing this for a long time.You can undo the bolts and slide it out of the coupling for checking.Tie a rope to the prop and give it only a few cm slack .This way you won't loose it .You can spin the shaft in neutral but not independently of the coupling .If they do the coupling is obviously loose.
You have a conventional stuffing box by the looks of it.It is tightned only until you get a drip every few minutes or so.No more .If you have a separate greaser give it a turn or two every few hours of running.If I were you I'd replace the stuffing box with a Volvo seal,providing the shaft bearing surface is in top nick http://www.volvopenta.com/SiteColle...Parts brochures/Rubber Stuffing Box (Eng).pdf and replace the coupling as well,they're quite affordable.http://www.asap-supplies.com/marine/boat-propeller-shaft-couplings

 

[Tranona]

Wow! Whoever did that installation wants a severe wrist slap! As 30 Boat says, the shaft is probably worn so clamping tighter may not cure. However, the main problem is lack of clearance between the coupling and the stuffing box.

As you will probably need a new half coupling as well, suggest you throw that whole lot away aft of the engine coupler and replace with a Centaflex flexible coupling (which is also the coupling on the shaft) and a Volvo shaft seal. This will be not only a better coupling, but will mean a short length of shaft showing between the coupling and the seal to allow the engine to move backwards and forwards on its mounts. You will have to unbolt the engine and move it forward as there is no way you can do anything with that coupling as there is no room to undo the connecting bolts.

 

[Bilgediver]

Wow! Whoever did that installation wants a severe wrist slap! As 30 Boat says, the shaft is probably worn so clamping tighter may not cure. However, the main problem is lack of clearance between the coupling and the stuffing box.

As you will probably need a new half coupling as well, suggest you throw that whole lot away aft of the engine coupler and replace with a Centaflex flexible coupling (which is also the coupling on the shaft) and a Volvo shaft seal. This will be not only a better coupling, but will mean a short length of shaft showing between the coupling and the seal to allow the engine to move backwards and forwards on its mounts. You will have to unbolt the engine and move it forward as there is no way you can do anything with that coupling as there is no room to undo the connecting bolts.

Yep....


Someone needs to be shot as above. That set up is a liability due to the inability of repacking the shaft gland without removing the half coupling to give access.

The engineer may have spotted thsi and in this case maybe his charge included for drying out as well .

As Tranona has said the coupling clamp bolts look in poor condidtion and your success depends on the state of the shaft. You can determine this by removing the four clamping bolts and the clamp half of the coupling which will let you se the shaft. If it is not too bad then either just clean up the nuts and bolts so the nuts run free or get four new bolts.

The gland may be able to wait till you are ashore if not leaking and then you will need to remove at least the shaft half coupling.