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Discussion Starter #1
There is a sort of slight “metallic shhhh noise”, you hear it if the engine is running and blade is disengaged. The faster the engine runs the louder it gets.
The second you engage the blade it goes away completely, at all speeds.
I therefore suspected it was one or both, of the Rotostop bearings. Mower is 2007 so 14 carefully maintained, years.

I removed the blade, all looked pretty clean, a light wash down and imo looks in excellent condition For 14 years see photos
Oddly Turning the blade by hand sounded fine no grating Or metallic shhh like noise.
Q1. Would you be able to hear a knackered blade brake bearing when turning by hand?
I then ran the mower without a blade (my logic was the weight of the blade might load these bearings i.e. explaining no noise with the blade off) . Sadly the noise was there when run with no blade.

To go further, one needs to take the central 14mm Bolt out of the end of the bottom of the crankshaft. Think Honda call it the Blade Holder Screw.
My Problem is holding the crank whilst unlocking and re tightening the bolt to 55Nm.
The shop manual says “Blade Holder Screw - Disassembly and Re-assembly. Loosen or tighten the Screw ‘with holding’ the Blade brake lever”.
I think this is rubbish, or my machine is broken. What does ‘with holding’ mean. I assume it means “by holding”.
In any event, with the blade brake lever free, the blade holder screw just turns the engine, and the only resistance is the engine compression! Depressing the Blade brake lever, does activate the clutch, so one can hold the blade with a wooden block, but the clutch slips way before one could get even close to 20Nm let alone 55Nm.
Am I misunderstanding these instructions? Or are they actually wrong?

Looking at this issue, many on UTube use an impact gun to undo this bolt, guess the bolt spins loose Before the crank has a chance to rotate?
But I don't like the idea of screwing up this bolt (designed for max torque of 55Nm) with an impact gun of max torque 270 Nm. Also how would you know it was tightening to overcome the big spring or really finally tightening into the treaded shaft?

My thoughts were to tighten it I need to hold the flywheel, not keen on that as a strap wrench means taking off the cowling and then the magneto and resetting the latter etc. A total pain.

I then noticed a big nut holding down the Flywheel (where the starter puller is) - it says its a 14mm “Special” Nut 75Nm. Does that mean its a left handed threaded nut?
Q2. Can I use a spanner on this Special Nut to “hold“ the crankshaft whilst doing up the lower Blade Holder Screw - bolt?
My logic being this Special Nut should tightened to 75Nm. And the Brake holder screw only needs 55Nm. And I will be using a manual Torque wrench on the bottom, slowly tightening it, effectively against the Nut on the other, top end of the crankshaft, which should be at 75Nm. Plus the top nut has not been snapped free, and has been there 14 years, so normally would need more than 75Nm to break free?
Admittedly if the top flywheel special 14mm Nut is a left handed thread??, then it should want to actually tighten the top nut? ( unlikely as it should be @ 75Nm and I am only doing the bottom nut to 55Nm.)
From the 1/3 of a thread visible, coming through this Special Nut, it looks like a regular RH thread?, so undoing the bottom nut would tend to effectively undo this special nut. I think they call it Special because it is such a big Flange Nut?
Or do I risk undoing the top special nut by accident?
Other issue:-
Looking at the lower exposed bearing it says its an NTN 6204 LU.
OK NTN is not great at explaining its suffixes, but it seems to be a single sided seal of Nitrile. That seems odd? OK the seal is toward the blade, but with wet grass, mud and dust semi trapped by the Blade Holder, surely this should be a double sided seal?
Q 3. Can I replace it by a double shielded, i.e. NTN 6204 LLU bearing?
Any help much appreciated.

Note: I am looking for a “decent” risk free solution to remove the Blade Holder screw, so I can use the method for a really good annual clean off and re-lubricate home service.
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for a
 

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Yes, that is the flywheel nut (m14) you can use it to hold the crank to loosen that bottom bolt. you'll need a torque wrench to properly tighten it to 55NM.
 

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Discussion Starter #3
Yes, that is the flywheel nut (m14) you can use it to hold the crank to loosen that bottom bolt. you'll need a torque wrench to properly tighten it to 55NM.
Thanks, I did see a post where someone said he tried this, but the M14 Flywheel bolt came undone first!
For that reason I was going to undo the bottom crank bolt with an impact gun. Not holding the top nut.
But use this Nut to hold the crank, just for tightening it with my manual torque wrench, very slowly.

Does that plan sound sensible?
 

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Can I use a spanner on this Special Nut to “hold“ the crankshaft whilst doing up the lower Blade Holder Screw - bolt?
The Rope Trick helps keep the valves closed while you're working and keeps them from falling into the cylinder and can also be used when tightening/loosening the crank bolts/nuts.

Fill Some of the Space Above the Piston
With the piston low in the cylinder, use rope made of something that won't shed any fibers. Feed the rope into the cylinder through the sparkplug hole. Continue to feed the rope into the cylinder, loosely filling as much of the cylinder as possible.

Rotate the Engine
Rotate the engine by hand until you feel resistance (the rope pressed between the piston and valves). If you have a broken valve spring and the valve does not close completely keep some upward pressure on the valve so the rope does not get caught between the valve and seat.

The Valves Will Be Held in Place by the Rope
Use a valve spring compressor (if necessary) to compress the valve spring, remove the keepers (a small magnetic pickup will help) and the spring. Complete whatever repairs are needed.

Removing the Rope
Rotate the engine in the opposite direction, relieving the pressure between the rope and valves, remove the rope, and you are done.
 

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Discussion Starter #7
The Rope Trick helps keep the valves closed while you're working and keeps them from falling into the cylinder and can also be used when tightening/loosening the crank bolts/nuts.

Fill Some of the Space Above the Piston
With the piston low in the cylinder, use rope made of something that won't shed any fibers. Feed the rope into the cylinder through the sparkplug hole. Continue to feed the rope into the cylinder, loosely filling as much of the cylinder as possible.

Rotate the Engine
Rotate the engine by hand until you feel resistance (the rope pressed between the piston and valves). If you have a broken valve spring and the valve does not close completely keep some upward pressure on the valve so the rope does not get caught between the valve and seat.

The Valves Will Be Held in Place by the Rope
Use a valve spring compressor (if necessary) to compress the valve spring, remove the keepers (a small magnetic pickup will help) and the spring. Complete whatever repairs are needed.

Removing the Rope
Rotate the engine in the opposite direction, relieving the pressure between the rope and valves, remove the rope, and you are done.
Thanks for the lovely detailed reply - much appreciated.
I guess its a pretty neat trick, as long as you make sure its on the compression stroke, so the valves are shut. Otherwise the piston could be pushing up on the compressed rope with one of the valves down ... and that wouldn’t be something I would be comfortable with.

What I find weird is Honda’s shop manual saying you can use the Rotostop Lever to hold the engine!
( imo that does not work) . Disconcerting as I have not found any major gaffs in Honda’s technical documentation before .... so suspected I was being dumb.
61783

thanks Peter
 
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