Re: Magneto is dead on 1961 Johnson Seahorse 75hp
Where do I get me one of those spark testers? Do They sell 'em on iboats.com?
If it doesn't jump like lightning then what? Bad coil? Coils run a $100 that's why I want to make sure... Thanks
Spark testers are nice, and almost a necessity for serious working on outboards. But for what you are doing at the moment, you don't need one. You can check for spark off the coil simply by laying a screwdriver against the housing and 1/4" away from the terminal. Or if you don't have 3 hands, rig up a piece of wire from one of the screw holes and bend it so it pokes 1/4" from the trminal.
Now back to the problem at hand. You either have a coil problem or you have a breaker problem which could include a shorted condenser.
You insist the coil looks good and has no arcing. So, let's assume it is good for now. That leaves the breakers assembly. The first thing you need to do is be sure the breakers contacts are absolutely clean, shiny, and gapped correctly. I always take them apart and polish each contact individually. Even oil from your fingers can foul them. Gap them to be open .020" at their widest opening or use the timing marks (better).
OK, you have done that now, so let's check them electrically. Do you have an ohmmeter capable of reading very low resistances? One that can tell the difference between one ohm and half an ohm? Not all can. If you don't have such a meter move on to the next step. But if you do have such a meter, disconnect the breaker plate wire from the magneto stud and connect your meter between the wire terminal and breaker plate ground. Slip the belt pulley on the shaft and rotate it slowly while observing your meter. It should read zero ohms when either set of points is closed and infinity when both are open. By zero, I mean zero--not .4 or .6, ---zero. You probably won't get true infinity, the difference represents condenser leakage. They all leak some. If you suspect that it leaks too much, they are cheap and easy to just replace. The change between zero and infinity should occur just as the timing marks align. If they are off a bit, that's due to error in points gap.
Moving on, once you have done all that, you can assume the breaker assembly is good to go. Now it has to be connected to the coil in order to do anything. That connection is through the stud on the side of the case. Remember how you had to polish the points shiny bright? All the parts of the stud connection have to be the same way. Sand or wire brush the screw, under the screw head, threads, nuts, wire terminals. When you put it together, you want to be sure electriciy can get through the connection without being blocked by non-conductive corrosion. ALSO, you do NOT want the electricity to be able to get to the housing. That means make sure the insulating washers are in good shape and installed correctly.
If you have done all that and not taken short cuts or assumptions, you should have a strong spark off the coil.
If you still do not have spark, either the coil is bad or there is a problem with installation. There is not much you can do wrong with installation, but make sure the laminations are in direct contact with the laminations in the housing. Make sure the ground wire is secure.
Determing whether a coil is good or bad without a tester is mostly a process of elimination. Eliminate the oher possibilities as I just described, and if you still don't have spark, it's gotta be the coil. I'm assuming you aren't ignoring something stupid like bad bearings allowing the armature to drag on the magnets or full of rust or other stupid obvious things.
Whew! You just got your diploma from Magnetos 101.
