quick question on 1965 merc 65 hp

mars bar

Petty Officer 1st Class
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Had the motor out several times and it ran wonderful. The last time out I had it at full throttle and then it quit cold turkey. Back at the dock, I removed the 1st and 2nd spark plugs and found no spark, had just replaced the battery with a 1000 cranking amp but I can't see that having any effect. I'm thinking stator? someone stated, that maybe my rectifier went and it sent an overload (amp) to the stator. Or it's just to old. Geez I love this old motor.Thank for reading Mars
 

racerone

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?????----------You mis-understand.--------The spark on that motor comes from the magneto.----------Battery / stator / rectifier have nothing to do with making the spark.---------------Take the bottom of the magneto off ( 4 small bolts ) and inspect it.-------May just need the points cleaned and re-adjusted.
 

emckelvy

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Before you pull the magneto, pull the kill wire off the side of the unit. It's not the uninsulated braided ground wire that's also attached to the mag body, but the insulated wire that has a nutted connection to a screw in an insulator, that sticks directly out the side of the mag, looking right at you.

If the key switch failed, it could be grounding-out the mag. If that proves to not be the problem, there's something that failed catastrophically to cause the no-spark. Ign points don't normally fail while the engine is running.

Not uncommon for the rotor to short out internally, so be sure to check for spark right off the coil, to the mag body, when you get it apart.

A relatively safe way of doing that is to lay the mag on the workbench, ground the shaft of a medium-to-large screwdriver against the alum. mag body, and hold the tip approx 3/8" away from the copper strip coming off the top of the mag coil.

Give the magneto shaft a sharp turn clockwise, and a strong spark should jump the gap. If it's orang-ish or won't jump, inspect points etc for problems. If the spark will jump off the copper strip, but doesn't get thru the rotor/cap, strongly suspect problem with the rotor. Clean the cap while the mag is apart; carb cleaner will flush out any crud/deposits.

2 other things I've seen that cause instantaneous ign failure are cracks/shifting of the insulator in the side of the mag case, where the kill wire connects. Also a "blown" coil; look for cracks and/or arc marks on the exterior of the coil. You may have to pull the coil from the magneto housing for a full inspection. Cut the safety-wire on the coil's lock-screws, loosen screws then remove coil.

Points are gapped to nominal .008". The mag driveshaft has a flat machined into it, and will only fit into the mag drive one-way. You'll find that there's a very small slot machined into the bottom circumference of the mag drive and this gives you a visual cue for orientation of the flat.

HTH, let us know what you find..........ed
 

mars bar

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I bought a manual on line and on inspection of my motor I noticed 2 wires going to that screw One comes from I guess is a mercury switch mounted on the side of the block made of plastic. The other wire is I think brown or a dirty yellow.
 

racerone

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???--Are you going to remove the bottom half of the magneto to do an inspection ???--Clean and sey the points ?-----If it has not been done for a while it is due !!
 
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emckelvy

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I bought a manual on line and on inspection of my motor I noticed 2 wires going to that screw One comes from I guess is a mercury switch mounted on the side of the block made of plastic. The other wire is I think brown or a dirty yellow.

Yeah, that is a switch full of mercury and it will kill the ignition when the motor tilts up after striking a submerged object. Be sure to disconnect that wire as well when checking for spark. Not a common failure but you never know!
 

mars bar

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Thanks Guys,Racerone I'm going to wait till I get the manual I've had only small Merc 1972 4.5 hp. i'm not to use to this bigger magneto stuff and I don't know exactly where to start but I'm going to follow both of your Ideas starting with removal of the wires.I'm assuming that I have to turn the key after that? What I did see was a lot of powdery material in the vacuum hoses and fittings from the distributor cap and one of the hoses was off it's fitting. Thanks It's a learn as I go process with your helps.
 

mars bar

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Wow, Took the Mag apart after removing wires no change. Took off the blue distributor cap, looks worn and little connection on electrodes. Took the mag cover off and I know I'm not supposed to have all those metal filings and metal flakes sticking up like the needles on a porcupine all over the points and stuff as well as a blob of grease. Tested the mag with the screwdriver ,no spark. The shaft is extremely hard to turn, then wouldnn't turn at all. I think I know where this is going. Mars
 

GA_Boater

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You probably need the two magneto bearings. 30-24998 Upper, 30-24997 or 30-49090 Lower. I got them on Ebay, there are other sources.

How did you test with a screwdriver if it's locked?
 
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mars bar

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I could only turn it a bit by hand with some force, then I couldn't turn it at all even with pliers. Wait just tried it with fingers and it's moving hard to turn though. I have hands like visegrips. How do you get at the bearings is the top a press fit after removing the 3 crews.
 

GA_Boater

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It's been a while.

Remove everything under the cap, #38 - Points, condenser. cover #32. You can leave the coil in place. One more word of caution - All these pieces are expensive and almost impossible to find.

After taking out the screws holding #7, press the shaft in the direction of the red arrow 1. then press the shaft out of #7 in the direction of red arrow 2. Be careful - The shaft is relatively soft and deforms easily.

Since you had a metal shards, one or both of the bearings disintegrated. The inner race(s) will be stuck on the shaft. Be careful, Yep, #5 is expensive..


mag.PNG

mag1.PNG
 

mars bar

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Wow, Thank you very much, You don't know what this means to me. Having my 2 nd motor breakdown on my vacation 2 years in a row. leaving the kids and I sitting on the dock. got me so upset I lost 5 months of sobriety that I had fought hard for.I'm ok now ,back to my meetings. Thank you again my friend. Mars
 

GA_Boater

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Don't let this get you down, Mars. It isn't important like life itself. If you hit a roadblock, just step back, take a deep breathe and drop a note here. Stay sober, buddy.
 

mars bar

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Thanks GA Boater I just need to remember what I was like before and The Serenity Prayer. .Calm waters to you. thanks again
 

mars bar

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It's been awhile but here's an update. The upper bearing was gone but that wasn't the real problem. The fact that the carbon electrode in the distributor cap as worn off. It's supposed to be spring loaded but some how was stuck. Bought a complete magneto in perfect shape for $250.00 US with shipping and exchange $400+ but boy does she go now. Thanks for all you help Guys. Oh the reason I bought another mag was because when my buddy was pressing the bearings in he broke the aluminium plate.
 

GA_Boater

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Yikes, Mars. I was really careful pressing the bearings because an unknown used magneto cost so much. My carbon button worn down too and it was sticking also. Sounds like we pretty much had the same experience. Except for the broken plate.

Glad you got it all working and thanks for the follow-up. :thumb: Sail on! :D
 

mars bar

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If you need a set of bearings let me know. They had lots at work LOL. So you don't want to pay me for coming in a half hour early hey. OK
 

merc850

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Here's the reassembly procedure kiekhaefer-magnetosm.jpg
make sure that when you put the red magneto cap on that it is centered to the shaft.
 
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