Magnets/1 cylinder Spark 1986 Mercury 25 XD

[rotor_av8]

I picked up a rib/inflatable boat in a trade that has a 1986 Mercury 25 XD 2 stroke. Ran like crap so I’ve done the following troubleshooting. Cleaned carb well. 130+ psi compression both cylinders. Discovered spark on one cylinder only, plugs both good. Ohm’d out coils (good). Swapped coils, they are good. New CDI, didn’t work same issue.

I discovered looking up and into the flywheel that one magnet slides around and is apparently detached. Do I have to buy a new flywheel? Should I epoxy the magnet back in place? Does JB weld work as well as the other stuff? I haven’t removed the flywheel yet but if both magnets are moved how would I locate them properly? I’ll try to attach screenshots from a video I took. Notice the magnets are together and one can be moved around. Flywheel part number is mercury 258-859232T15 not a cheap part so I’d like to try epoxy, any good luck with this?

 

[flyingscott]

Where are you located? A used flywheel is much cheaper.

 

[racerone]

Epoxy can be used to put it back in place.

 

[rotor_av8]

Where are you located? A used flywheel is much cheaper.

I am in Northeast Washington State

 

[rotor_av8]

Epoxy can be used to put it back in place.

Have you done the epoxy before? Has anyone had good success with JB weld or should I get the magnet epoxy in a tiny package?

 

[racerone]

BRP ( Johnson / EVINRUDE ) markets a kit to re-install magnets in flywheels up to a V-6 .----Comes with instructions of course.----You may have to observe polarity when doing this procedure.

 

[rotor_av8]

BRP ( Johnson / EVINRUDE ) markets a kit to re-install magnets in flywheels up to a V-6 .----Comes with instructions of course.----You may have to observe polarity when doing this procedure.

Ok, I’ll double check the polarity. Are there markings on the flywheel? Online it looks like many use the regular JB Weld. I haven’t tried to get the flywheel off yet but maybe I should soak it with some break free for a while. From what I gather don’t use a hammer. Hopefully a flywheel puller will work.

 

[rotor_av8]

Also I only have two magnets since I’m a 2 banger.

 

[racerone]

Sorry----If it is confusing then search for a used flywheel.-----There are LOTS of them around.-----Do not understand why the flywheel might need soaking with any ---" mechanic in a can " ---to get it off.----Use the proper puller I say.

 

[rotor_av8]

Sorry----If it is confusing then search for a used flywheel.-----There are LOTS of them around.-----Do not understand why the flywheel might need soaking with any ---" mechanic in a can " ---to get it off.----Use the proper puller I say.

So, you mean buy a special puller for this engine specifically? I’ve heard they are a specialty item. Is that correct?

 

[flyingscott]

No a harmonic balancer puller works. Take the bolt out of the flywheel and take the washer off. Then put the bolt back into snug. The bolts to thread into the flywheel are metric.

 

[rotor_av8]

No a harmonic balancer puller works. Take the bolt out of the flywheel and take the washer off. Then put the bolt back into snug. The bolts to thread into the flywheel are metric.

Yeah I’m having a hard time figuring out what they are too. I have a balancer puller and the bolts don’t fit. I tried a set from the hardware store but they were wrong so have to keep trying. Does anyone know the size?

 

[rotor_av8]

Ok I’m ending this topic with one last update. My magnets were loose and broken. For anyone having this issue and following this thread...With the cover off look under the flywheel on the left, port, side. Slowly rotate the flywheel and you can see the magnets on the inside where they pass the pickup coil toward the left front. There are two magnets and they should be on opposite sides of the flywheel from each other. They are epoxied on and it’s common for them to come loose. One of mine was loose. I broke the second magnet removing the flywheel. I am ordering a replacement flywheel so won’t need the extra loose magnet. If you end up needing one I could sell you mine. I couldn’t find them anywhere for Mercury. If you end up pulling the flywheel a harmonic balancer puller from O’reilly or an auto parts store works and they end up being free to rent. The bolts in the puller kit won’t work but the two bolt holes on the flywheel take 3/8” -16 thread bolts 2.5 inches long. An impact driver and no hammering on the flywheel. I hit mine what I thought was lightly with a ball peen hammer and cracked the other magnet. It could have already been broken too though. Hope this isn’t too much info but if a magnet has moved it will screw the timing or make your engine run on one cylinder or less than it is supposed to and it’s easy to check for without removing anything but the engine cover.

 

[flyingscott]

Those holes are metric in the flywheel. Obviously your flywheel had been removed prior and probably removed improperly before. Probably why the magnet fell out on it.