How to separate prop shaft from Volvo Penta 2020

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kspirit53

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In preparation for eventually changing the Volvo shaft seal, I am trying to loosen the four flange bolts which connect the prop shaft to the engine, but, unfortunately, I have been unable to prevent the prop shaft from rotating. Any tips for stopping this whilst the boat is in the water? Engaging engine in gear increases resistance, but not by enough.
 
/forums/images/graemlins/shocked.gifyou're not going to change the Volvo shaft seal with the boat in the water are you?

Why are you removing the prop from the engine? You need to release the prop from the coupling so that you can slide it back to replace the seal. In most cases it is not necessary to detach the coupling from the engine - in fact on my boat it would very hard to loosen the prop if the coupling wasn't held in place. OK, if it is jammed in and won't come out then placing a nut in line with the end of the prop and tightening the coupling bolts might press it out (providing all grub screws or roll pins are removed).

If you are on drying mooring then fair does. When I undid the coupling on mine to remove the gearbox I got someone to brace a piece of wood against the prop. If you can't do that then perhaps you need to shock each bolt loose with a sharp whack whilst using another socket/allen key to brace the opposing bolt. This technique worked well as a two man job when reattaching the ring to the flywheel.
 
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It it's one of these then you should be undoing the 6 bolts not the four.

You'll need a punch to remove the pin(s) though. Not shown in the link.

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Sounds like he is trying to remove the coupling not just undoing it to release the prop. Hence my comment.
 
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Sounds like he is trying to remove the coupling not just undoing it to release the prop. Hence my comment.

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You don't know the size of hex key for those bolts do you? Only I've got to separate the coupling this w/e to check the alignment. I've got a socket set hex set with 7,8,10,12,14 and 17. Knowing my luck it will be 9 or 11 mm !

Fortunately I've got a 3' long mole wrench to hold the shaft still. Granddad was a gas engineer.
 
normally on the 20x0 series there are 4 allen screws holding the flange on, you need to get this apart first, i have a tyre lever that I slip between the head of the next allen key and the flange and jam it against the hull, just keep moving around till they are all loose, UNDER NO CIRCUMSTANCES use a stilson or mole grip to hold the shaft, it will ruin the finish and the volvo seal will be damaged on the bits raised by the wrench. (even when you use the protector red tab, it will still damage it)
slide the shaft down the tube and undo the pinch bolt and indent screw on the flange, carefully knock a screwdriver into the split to ease the grip of the flange on the shaft and tap it off, remove the key and then change the seal, use the provided red tabbed doofer to protect the lips as you slide the seal back in to postion, using loads of the blue grease that comes with it, re assmble in revers
Stuposition.
 
Just to intrude; there is a tightening procedure for torquing up the coupling when you come to refix it. You tighten twice; first tightening to 30 newtons, second tightening to 65 newtons. The order of tightening is to start at the flange end, alternating each side before moving backwards. That's for shaft sizes 25mm to 30mm. For 35mm there will be eight screws and you need to do a third tightening to 95 newtons. The instructions don't quote a size for the hex I'm afraid but I agree with MoodySabre. When I did mine it was nothing out of the ordinary.
 
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