testing a front coil

[cdv]

is there a way to test a front mount coil on my 9n do not know if its good or not thanks cdv

 

[JMOR]

(quoted from post at 22:42:18 12/01/10) is there a way to test a front mount coil on my 9n do not know if its good or not thanks cdv

he only real test the owner can usually make is to see if it runs over time & temperature. A partial is by measuring primary & secondary resistance to establish opens, but if that is OK, the insulation may be broken down at temperature and/or under high voltage.

 

[Bruce (VA)]

Coil problems are difficult to diagnose. For starters, round coils are pretty robust & square coils aren’t (because of the difference in insulation used), but neither one will hold up to a poorly done 12v conversion that allows too much current to the coil or leaving the key on (see tip # 38). Too much current creates heat which melts the insulation. Insufficient resistance in a 12v conversion will do the same thing. Rarely do coils just “go bad.”



There are a few ways to see if a coil is bad, but it’s not possible to determine if a coil is good w/o some expensive testing equipment. If you detect a dead short or high resistance in the coil w/ an ohm meter, it’s bad. If it’s cracked, it’s bad. If a sidemount coil w/ battery voltage to the primary will not jump a ¼” gap from the secondary wire to the block, it’s bad. But, here is the hard part: even if you do not detect a short, even if it will produce a spark, even if it’s not cracked, that doesn’t mean the coil will work when it’s hot & under a load. So, it’s a process of elimination. If the tractor starts & runs fine for 30 minutes or an hour then cuts off & refuses to re-start, and you checked for spark at the plugs & it had no spark at all, AND you have the correct voltage at the coil that’s a good sign that you have a bad coil. Let it cool off, restart it & if you have a good spark, odds are it’s a bad coil. But, even then, you might end up w/ a spare coil on the shelf!



Bottom line.......coils do go bad, but I'll venture a guess that 75% of new N coils sold today are sold to folks who do not understand how to diagnose a poor spark problem or how a coil works. So, for those who don’t know any better, in a no spark situation the first suspect is usually the coil……and, more often than not, it isn’t the problem.

Why not tell us what problems you are having that caused you to suspect that the coil might be bad?
50 Tips

 

[36 Coupe]

You can test a coil on the bench.You need a spark gap,spark plug works.a 6 volt lantern battery for power.Dont try to use a battery charger,the inductive kick will eat the diodes.You need a condenser in the circuit.When you disconnect the battery a spark should happen.You could use a n old distributor with a hand crank on it to make a tester.You do have to be sharp enough to under stand how an ignition works to run the test.

 

[souNdguy]

you already have a big cast iron coil tester there in front of you.

ccrank her over and see if it makes spark.

if it does.. run her untill warm and see if it makes spark.

soundguy