How do I replace the cutless bearing on a Sun Odyssey 36i?
I've got a 2008 Sun Odyssey 36i with the standard Yanmar 3YM30. There's a lot of play in the prop shaft when I wobble it on the hard, so the cutless bearing is shot. How do I actually get the old one out of the P-bracket and fit a new one without damaging the hull?
Answer
To replace the cutless bearing on your Sun Odyssey 36i, you must remove the propeller, extract the P-bracket grub screws, and press the old bearing out using a threaded rod tool. The standard replacement for the factory 25mm shaft is a 25mm inner diameter by 40mm outer diameter brass-shelled bearing, which costs around £45.
Preparing Shaft and P-Bracket
Most Jeanneau Sun Odyssey 36i models from this era feature a Yanmar 3YM30 engine and a 25mm stainless steel prop shaft. Put a pair of calipers on your shaft just forward of the P-bracket to confirm the 25mm measurement before ordering parts. Some owners retrofitted 1-inch shafts. You need a standard brass-shelled or phenolic resin cutless bearing measuring 25mm inside diameter, 40mm outside diameter and 100mm in length. Vetus or Exalto supply reliable replacements.
Block the shaft inside the boat near the gearbox coupling. This stops it sliding aft and straining the shaft seal while you work outside. You must remove the propeller first. Take out the split pin, undo the locking nut and use a heavy-duty three-leg puller to pop the prop off the taper. Leave the main nut loosely threaded on the shaft end. The propeller will not fly off and hit you when the taper breaks free.
Removing the Grub Screws
An interference fit and two stainless steel grub screws hold the cutless bearing inside the bronze P-bracket. These set screws sit on the sides of the P-bracket at the 3 o'clock and 9 o'clock positions. Years of antifouling paint and primer usually bury them.
- Scrape the sides of the P-bracket bare with a chisel until you expose the flush heads of the grub screws.
- Clean the hex sockets out completely using a sharp pick. Rounding off an Allen key in a fouled screw head means you must drill it out.
- Use a tight-fitting Allen key to back them out. If they seize, apply a butane blowtorch directly to the P-bracket around the screw for sixty seconds to melt the old threadlocker.
Pressing Out Old Bearings
Never hammer the old bearing out of the P-bracket. Hammering shocks the bronze casting and fractures the fibreglass matrix where the strut enters the hull. This leads to massive structural repairs.
You can hire a commercial tool like a Strut-Pro. Making a puller is cheaper and highly effective. Buy a length of M12 high-tensile threaded rod, heavy-duty nuts and thick washers. You also need a pusher. An impact socket with an outer diameter of exactly 39mm fits inside the P-bracket. Find a receiver tube larger than 40mm for the old bearing to slide into.