I think I have a bad ignition coil on my lt30 onan

[Jeff]

My Sawmill won't start. Cranks but won't fire.  Its an Onan P224     I have 12 volts on the positive side of the coil, and when putting the test light on the negative, then cranking the engine over, I get intermittent voltage pulses like I should. but using a test plug, I see I have zero spark on either cylinder.

I have another replacement coil here for it,, but it has a problem. One of the studs is broken off.  Do you guys think I could solder a wire to it?

[Tom]

My gut feeling is that heat would damage the coil and a butt joint wouldn't hold, even with silver solder.

If there is room, I would flatten another bolt and lay it at a 90 and super glue it, then have my attachment over to the side.  That might tell whether the coil is OK. use just  spot of glue so that raw metal touches raw metal.

If there are enough threads showing, a nut might be put on there and then another bolt run down into the top of the nut and butt the two threaded bolts/studs together.

You might be able to stay away from too much heat by soldering a wire to the broken bolt and run it to another fastener.  Heat's gonna be a problem

[Bro. Noble]

Or you might be able to drill a hole into the broken bolt and tap it.  You could then screw a wire onto it.  My experience with super glue is that it holds well for a while and then lets loose.

[pineywoods]

Bro Noble got it right. Any heat applied to that broken off stud will melt plastic and probably un-solder the internal wire. Glue won't work, it's a pretty good insulator. Just drill a small hole and tap threads in it.

[Gary_C]

Tom is right. It's going to be difficult and maybe impossible to get the top of that stud hot enough to get the solder to flow without burning up the surrounding material and ruining the coil.

Another possibility would be to drill a smaller hole, not too far, right down thru that broken stud, tapping the hole and screwing a smaller screw in to hold a wire. Just file the top of that broken stud flat, center punch it to keep the hole in the center of the brass material and drill a hole for a tap. There should be enough material below the surface to get a few threads to hold a screw. You will probably have to get a bottoming tap that is not tapered or grind the end off of a tapered tap.

Or you could just get another coil.   

[Jeff]

I talked to Rick Lauman, and from the tests I ran, its definitely the coil.
New coil is over $130 :-\

My friend Harold is stopping by in a bit. Maybe he has a tap set.  I dont.

[Bro. Noble]

DanG Gary,  you must be a genius,  where did you go to school anyway? :D :D :D

[Jeff]

Another thought.  Jb weld is not conductive, but it is machinable after it hardens.  What if I put jb weld over it, then drilled and tapped down through that and just into the top of the stud.  I would then have something a bit more substantial to hold a screw without the fear of drilling the stud out to far?

[Bro. Noble]

Saw the stud off of the bad coil and then drill it out for practice to see how much material you have to work with.  Maybe you don't have to mess with the JB weld.

I just found out that Gary C aand I attended the same institute of higher education 8) 8) 8)  But so did Beenthere,  so that blows the genius theory :D :D :D

[Tom]

The last time I was in Radio Shack, there was still a remnant of Archer Electronics in there and I remember seeing something called "cold solder".   Don't know anything about it, but it might be worth researching.

[Gary_C]

DanG Gary,  you must be a genius,  where did you go to school anyway? :D :D :D

Where all smart guys go, how about you?  :D :D Just saw your latest post. Must be just those forestry guys.  :D :D

Most hardware stores have individual taps in those small sizes. They are usually not very expensive. Brass is easy to tap cause it's so soft. But you can easily dull that tap if you hit that hard plastic on the coil as it's rather abrasive.

If the tap method fails, you could also take a hammer and chisel and break away the plastic around the stud and hopefully connect directly to the wire. At that point, what have you got to lose.

[bandmiller2]

I'am going to swim agenst the tide here,those coils use a bakalite material and are quite heat resistant.A pistol grip soldering gun hot with a drop of solder on the tip touched quickly to the post ,clean and fluxed, and your all set I've done it before.Frank C.

[Gary_C]

Yes, soldering could work, but that brass is also good at transfering heat as well as electricity and by the time you get the top side hot, you may be damaging something on the inside. And those pencil type of soldering irons will likely not be hot enough and like you said, you will probably need a gun type of iron.

[customdave]

Ouch , 130$ for a coil, just thinkin outlound  here but is their a chance to out source a jobber coil for way less money, I would think a jobber one would be 30$ instead of 130$ ??


                                    Dave

[ladylake]

I'm with Frank , give solder a try.   Steve

[beenthere]

Some on eBay, a bit cheaper.

[metalspinner]

If there is a thread or two sticking up there, a brass nut threaded on that then a new post screwed into the nut will give you a new post.  Chasing just a bit of solder into the assembly or on the outside of the assembly will hold it tight.  Just don't get crazy with the heat.

[Jeff]

The photo makes it appear like there is more then thee is.  There ia about a half a thread there.  Not enough to do anything with.

Wrong Part numbers I bet. Supposedly not just any coil will work. Harold and I are going to try and drill it tonight.  We were mulling over the idea of just making a twin coil setup.  Why could we not use two regular auto coils mounted together, wired parallel.  The onan fires both cylinders at the same time, so there should not be a timing issue.  It might not be pretty, but we might be able to make something work with parts on hand

[ladylake]

The 2 coil plan sounds good to me if the repair doesn't work.    Steve

[Slabs]

First: I'm nixing the two-coil fix.  The triggering mechanism probably won't carry it.

Ultimately: I'm going with the solder guys.  Yes the coil is intended to be located in a hot environment.  I've done a lot of repairs like that with great success with most except a couple of lawn mower headlight connector tabs(but we won't go there).

Clean the brass base as well as possible.  Use a good cleaner/flux even if it's acid like the Stay-Brite liquid.  Tin the wire first and form it into a loop to fit around the remainding stud.  Have the iron/gun good and hot, cleaned and tinned before you place it onto the work.  Assure the wire is placed firmly on the stud and can be held there while the solder hardens(a buddy with a pair of needle-nose might be handy).  Apply the heat and solder almost simultaneously and be generous with the solder.  As soon as the solder appears to have tinned onto the lug, remove the heat quickly and assure the joint remains still until the solder hardens.  Stay-Brite silver bearing solder can be applied in this manner with little more heat than 60/40 tin lead and will tin much quicker.

As soon as the joint has cooled somewhat clean off the residual flux with water and something like an old tooth brush to avoid the possibility of corrosion.

Good luck

[Jeff]

I went with the drill tap and put in a stud method.   Never drilled past solid brass, so I'm thinking things should be Okay. Tightened in the screw, then used loctite on the jam nut.  I'll give her a try tomorrow.

[customdave]

Looks like a new one, sawdust should fly. Nice job by the way!

              Dave

[Gary_C]

Looks great. Nice job.

Does the old one show signs of overheating?

[Jeff]

The old one just simply looks weathered. The black plastic is starting to look a bit gray.

[bandmiller2]

You done good Jeff,those two teat coils are made up special for onan and theirs little you can do to avoid using them.If I recall a friend had a bad one and tried to cobble up a replacement,ended up buying one.Frank C.