what exactly does a coil do? AND are mine bad?

[chrysler1977]

First, what does a coil do?

Second, are mine bad? My two coils alternate between each other in getting very hot as I turn the key (note, the boat doesnt start yet... I think i need a new solenoid because it doesnt work unless I bypass it by using two screwdrivers to make the connection)...ive discovered while I am turning the key just to "see what happens," one of the coils will get super hot. And then the next day, the other coil may be the one getting hot while I do this. a picture of similar coils can be found at: http://www.chrysleroutboards.com/chrysler_outboard_parts_and_serv.htm look at the one about half way down that says Size comparison of 12V coils F380475 & F2A91475.

do you know if these coils are supposed to get hot/stay cold/alternate? and also, I am not sure what exactly the coils do?

45hp chrysler 1978 model 457H8J if that helps....

thanks!

 

[NMShooter]

Re: what exactly does a coil do? AND are mine bad?

A coil is an inductor / transformer that allows you to take 12V and create a small pulse of electricity at a much higher voltage. 40,000 volts or more is not uncommon.

You probably have three contacts on the coil. A ground, a primary contact and a secondary contact which goes to the spark plug. Take an Ohmmeter, and compare the readings on the coils. Primary to ground should probably be less than one Ohm. Make sure to zero out your wire resistance before you measure. Your secondary to ground should be on the order of (I'm guessing, check a manual) 800 to 1100 Ohms. The important thing is for the coils to measure the same amount.

Since one unit and then the other is getting hot, I'm betting it is not the coils, but it is your control unit. Have you done a spark test on your plugs?

 

[Frank Acampora]

Re: what exactly does a coil do? AND are mine bad?

Since you say you have two coils, that means you have a two cylinder engine with two sets of points. The cam only has one lobe, so depending upon which set of points are closed, that coil will get the current, Now, passing current through the coil without the engine running leaves the coil energised for a much longer time than when the engine is running. Therefore it will get hot. With the engine running, both coils will get equally warm.