Coil failure. What causes them to fail?

[Dan_IN_MN]

I've been thinking about why coils fail. Anyone out there in the "know" about coils?

 

[Jacob J.]

I've seen them fail from excess heat, vibration, or even just having the flywheel rub the laminates for a long period of time.

 

[Cstratton]

Majority of failures I have seen I can chalk up to vibration. 2nd would be heat.

 

[little possum]

Subscribing.

I just fixed a lil Poulan for a friend that the coil suddenly went bad on. Good possibility that it was overheated like JJ said though. This guy keeps his truck and boat spotless but the saws are FILTHY!

 

[lawnmowertech37]

having dirt clogged inside the area of the coil can cause heat and therefore failure of the coil

 

[ken morgan]

heat is the biggest problem at least for automotive coils, it can cause the coating on the wire to become thin and cause a spark to jump internally once it does that one time its toast as it will continue to internally short.

 

[Boomer 87]

Moisture. Some coils are more susceptible than others homelite super xl comes to mind I've gotten by with the baking trick a time or two

 

[ken morgan]

is that due to shorting across the exterior of the case? i have noticed that certain coil packs are more prone t that then other in car

 

[nitehawk55]

High voltage (15-20K) breaks thru the insulation of the fine wire windings inside the coil causing a short , that is usually the cause or there is an open (break in a wire) inside the coil and heat can cause it to open or close due to expansion .
Some have had luck baking them , this sometimes reseals the insulation causing the short .
A failure can happen any time , old or new .

 

[Boomer 87]

The baking isn't a permanent thing either I wouldn't do that to one I was going to sell but on my own it's worth a shot.