CASE SI Magneto Issue

Anonymous-0 · Jun 11, 2009

I have totaly restored a 1948 Case SI. Now that its time for the final coat of paint I wanted to make sure of no leaks or problems. To my surprise no spark. Cleaned points and connections on the mag. Some spark but not enough. I have taken this mag to my local airport mechanic and he got it working. Here is the best part.....It will start great and run like a dream, but after 30 min or so and going to shut off and restart has an extremely hard time restarting. Trouble shot for awhile and found that there was not spark during crank. Took it back and forth to this guy 4 times and he finly put parts in it from a SLICK brand mag. Tried it again and it is doing the same thing.....warm up.....hard start...barley a spark. Now the guy is getting mad at me thinking its another engine problem. Does anyone have an ideal. Its not the typicl 4jm mag that most SC cases have as those have a black top that also comes off. This one only has the cap in the back and the eagle casted on the right side. Thanks ahead for any information.

Zach

John T · Jun 11, 2009

Sorry, I dont know beans about that particualr mag, all I can say is in some cases where the spark goes bad ONLY AFTER she warms up, it may be EITHER a bad coil (insulation breaks down once shes warm n expands) or possibly a condensor problem. A low voltage ohms continuity check can only show if a colil is bad (open or shorted winding) but NOT if its good i.e. she may break down under high voltage conditions once warmed up but test okay at low voltage (ohm meter or continuity tester) when cool. For no more then they cost, may as well try a new condensor first if he hasnt already and check n clean n gap the points

John T

teddy52food · Jun 11, 2009

I am not real sure on the mag you have, but some of the Case mag coils can be replaced with a Fairbanks Morse coil. Sounds like a coil or condenser problem.

John B. · Jun 11, 2009

There is such a thing as a condenser tester it's not an ohm meter. This tester will build up the condenser and measure it's rate of discharge. It'll show if they discharge slow or fast. My uncle has one and that's the only one I've seen.

greygoat · Jun 12, 2009

Good spark when cold, but poor when hot, and
trouble starting, when hot, can sometimes be
traced to a failing coil.
I've never worked on a SLICK brand magneto but
understood that they are an aircraft magneto
company, still in business today, who bought the
rights to Case magnetos.

KF · Jun 12, 2009

Sounds like what our magneto on the F-12 would do. We traced it to the coil. If it is the original coil in the magneto, then I would bet on the coil being bad. The insulation has broken down and it won't fire until it cools down then it is okay again.

Anonymous-0 · Jun 13, 2009

Ok. Thanks for all the help and information guys. I really appreciate it. I will further have to talk to the gentleman at the airport of what is being replaced. Again thank you.

CASE SI Magneto Issue

Anonymous-0

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John T

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teddy52food

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John B.

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greygoat

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KF

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Anonymous-0

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