2004 115hp EFI - Flywheel nut loose

Kronos

Seaman Apprentice
Joined
Nov 20, 2017
Messages
35
I'm helping out with a 115hp EFI 2004 Mercury which the flywheel nut has come loose on... There is some damage on the last few threads on the bolt coming from the flywheel and also on the threads of the bolt - it can be threaded back without any problems...

But, how should I put this back? I checked spares on link below and it seems there is no replacement nut avaibable? Is that really so?
https://www.marineengine.com/parts/...i-4stroke/0t801000-thru-1b226999-usa/flywheel

If so... how to re-use the old bolt? In order to torque it properly I need to fix the flywhell right? Can I use some loctite to make sure it sticks - even if the threads are i bit damaged?
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
The bolt you're talking about isn't a bolt. It's the crankshaft. The threads should be carefully chased with the proper die.

The nut is a 36MM metric nut, a Nylock I think.

Probably nothing wrong with the flywheel if the magnets didn't get knocked off if it spun up the shaft.
 

Kronos

Seaman Apprentice
Joined
Nov 20, 2017
Messages
35
Thanks. Will check the old bolt if it is nyloc or not - but will not be able to insepct now. Next weekend project.
 

Kronos

Seaman Apprentice
Joined
Nov 20, 2017
Messages
35
But regardless, does anyone know how to reassemble? How to apply enough torque without the crankshaft turning?

Can I and should I use some type of loctite to be sure it holds?
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Use a strap wrench to hold the flywheel.

If you fix the damage and use the proper nut, no Loctite is needed. If you jam it together, no amount of Loctite will keep the flywheel secure.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,780
I use an air operated impact wrench on any shaft that would otherwise require a means to hold.....to prevent turning. Impact performance just hits and skips fast enough that inertia can't build up in the shaft causing it to turn, both removing and installing nuts requiring up through 1 1/16" socket for a number.

150 ft-lbs on the torque for my 90-125 hp 2 stroke Mercs; serv. man. number. How do I get that? With 100 PSI of air pressure and a good ½" drive impact tool (Harbor Freight 450 ft-lbs, for roughly 75 bucks give or take),

While energizing the tool, I watch the socket run down on the flywheel and watch the socket turn against the wheel. When it stops turning I let the tool whack an additional half a dozen hits and quit. Simple solution.

Ebay has a lot of parts that you can't find otherwise from different types of suppliers, especially on parts no longer available. I just bought a couple of Merc. OEM fuel system parts for my 2002 115 that I couldn't find otherwise. I use them frequently for all kind of parts and haven't had a problem. Well managed site and very customer satisfaction friendly.
 
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