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Bad coil?

Your old Chris-Craft electrical system can be a challenge. If it runs on "juice" pose your questions and offer your advice here.

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tparsons56
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Joined: Tue Jan 25, 2011 8:02 am

Bad coil?

Post by tparsons56 » Wed Jul 03, 2019 5:00 pm

Having just been towed back home for the second time this year was not how I wanted to start my vacation. My 1941 Custom with M engine starts and runs great when cruising but then dies when the engine is warm and idling. It will cough a couple of times before dying but once it dies it will not start until the engine is cold again.
I once had a 1940 Ford 9N tractor that had a coil that went bad and it did the same thing so I am thinking coil - anyone else have this happen?

tparsons56
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Re: Bad coil?

Post by tparsons56 » Wed Jul 03, 2019 5:14 pm

I probably just answered my own question. I just went to check the engine and while the engine temp. Is now less than 100f the coil is scorching hot. The engine has been converted to 12v so what replacement coil should I be looking for?

jfrprops
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Location: Powhatan Courthouse Virginia

Re: Bad coil?

Post by jfrprops » Thu Jul 04, 2019 7:11 am

I can't specify a coil...but if that thing is converted as you mention...maybe you need a coil resistor if using an old style 12v coil....some coils have that built in...but others require the seperate ceramic and wire resistor...not having that working right causes wierd problems usually noticable at throttle up though???

John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

tparsons56
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Re: Bad coil?

Post by tparsons56 » Thu Jul 04, 2019 7:25 am

After it sat for a couple of hours it fired right back up. Since I have had this boat (three years) it has run flawlessly and nothing was changed over the winter which makes it confusing. I will pull the coil today to see what it is.

jim g
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Re: Bad coil?

Post by jim g » Thu Jul 04, 2019 7:27 am

Do you have a Pertronix ignition in your distributor?

tparsons56
Posts: 44
Joined: Tue Jan 25, 2011 8:02 am

Re: Bad coil?

Post by tparsons56 » Thu Jul 04, 2019 7:53 am

No. After the first time the engine died I replaced the cap, rotor, points and condenser that I got from Jim Staib and it ran great at the dock. It only died when idling after running at half throttle for about 20 minutes.

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drrot
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Re: Bad coil?

Post by drrot » Thu Jul 04, 2019 8:11 am

Sure points to a coil.
Jim Staib
www.finewoodboats.com


1947 Penn Yan 12' Cartopper WXH474611
1950 Chris-Craft 22' Sportsman U-22-1532
1957 Chris-Craft 26' Sea Skiff SK-26-515
1968 Century 17' Resorter FG-68-174

jim g
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Re: Bad coil?

Post by jim g » Thu Jul 04, 2019 9:16 am

Since you still have points. Go to NAPA and get a 12 volt internal resister coil. Buy the top of the line.

All the other auto parts stores sell coils that are junk.

jim g
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Re: Bad coil?

Post by jim g » Thu Jul 04, 2019 4:19 pm

You want NAPA number IC14

tparsons56
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Joined: Tue Jan 25, 2011 8:02 am

Re: Bad coil?

Post by tparsons56 » Fri Jul 05, 2019 11:20 am

I just put a new Napa IC14 coil on and it fired right up but the real test will come with the test drive. I will need to wait until I get a buddy with a chase boat to follow me.

jfrprops
Posts: 2056
Joined: Thu Dec 29, 2005 10:41 pm
Location: Powhatan Courthouse Virginia

Re: Bad coil?

Post by jfrprops » Sun Jul 07, 2019 12:10 pm

I am telling you guys...those resistors in or around the coil can, when failed, seem like any number of seemingly unrelated problems. Their whole purpose is to keep from overloading the points at max electrical delivery at while cranking....or at least that is the theory...??????.real gremlins...and coupled with bad and phony repro parts... = real nightmare.
John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

jim g
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Joined: Wed Dec 14, 2011 10:55 pm

Re: Bad coil?

Post by jim g » Sun Jul 07, 2019 12:51 pm

The IC 14 is an internally resister coil.

So no external resister needed.

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Bilge Rat
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Re: Bad coil?

Post by Bilge Rat » Mon Jul 08, 2019 7:53 am

Whether the coil comes with the resistor internally or you use an external ballast resistor, the resistor will get hot in use. When it's in the coil, the coil will be too hot to touch after running a while. An external ballast resistor is encased in a ceramic housing for a very good reason, it will normally get hot in use. Either style can intermittently fail and magically start working again when cooled down. I always carry 2 spare coils on board to save the day and MAYBE prevent the tow of shame back to the dock.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

tparsons56
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Re: Bad coil?

Post by tparsons56 » Mon Jul 08, 2019 9:17 am

I just got back from our sea trial and everything ran great so thanks to everyone for their input. I do agree that carrying a backup set of ignition parts and coil will be part of my protocol now.

tparsons56
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Joined: Tue Jan 25, 2011 8:02 am

Re: Bad coil?

Post by tparsons56 » Mon Jul 08, 2019 9:21 am

Also I noticed that while the new coil was quite warm to the touch it was far cooler than the old coil. That leads me to believe the old coil was “fried”.

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Bilge Rat
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Re: Bad coil?

Post by Bilge Rat » Mon Jul 08, 2019 9:24 am

Glad to hear the problem appears to be solved. The fix is also quite reasonably cheap and easy to change out the bad one too.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

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tkhersom
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Location: Edgecomb, Maine

Re: Bad coil?

Post by tkhersom » Fri Jul 12, 2019 6:32 am

Glad to hear the problem is solved!

FYI: I was always taught that the reason for a coil failing when hot, but working again when cooled is because it is just what it says it is. A coil of wire inside. If the wire has an open in it the flow of electrons will jump the gap when cold and close together (maybe even touching), but as the coil heats up the whole thing (inside) expands and the gap in the broken wire gets larger until the electrons can no longer jump that gap thus "No Spark". Once the coil cools down and the gap becomes small enough the electrons will flow again and vwolah "Spark". Just like magic.
Troy in ANE - Former President CCABC

1957 CC 21' Continental "Yorktown" (Mom's boat)
https://www.chris-craft.org/boats/22625/
1958 CC 38' Connie "American Beauty"
https://www.chris-craft.org/boats/22607/
1985 Formula 242LS "Gottago"
1991 Formula 36PC "Band Aids"

Life Is Too Short To Own An Ugly Boat

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Bilge Rat
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Re: Bad coil?

Post by Bilge Rat » Fri Jul 12, 2019 6:57 am

I think Troy's on to the magic, but I think its more like witchcraft.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

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mbigpops
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Location: Eastern Massachusetts

Re: Bad coil?

Post by mbigpops » Fri Jul 12, 2019 10:41 am

"vwolah". Interesting spelling of viola. What kind of Frenchman are you ? Did you graduate the Matt Smith spelling academy ?

Mark
1953 CC Rocket Runabout "Rocket Man"

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tkhersom
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Joined: Wed Feb 27, 2013 6:56 pm
Location: Edgecomb, Maine

Re: Bad coil?

Post by tkhersom » Fri Jul 12, 2019 8:53 pm

Precisely!

Matt and I spell finetically. Speaking of which why is that word spelled with a ph? Isn't that against the whole concept? :lol:
Troy in ANE - Former President CCABC

1957 CC 21' Continental "Yorktown" (Mom's boat)
https://www.chris-craft.org/boats/22625/
1958 CC 38' Connie "American Beauty"
https://www.chris-craft.org/boats/22607/
1985 Formula 242LS "Gottago"
1991 Formula 36PC "Band Aids"

Life Is Too Short To Own An Ugly Boat

davidvn
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Joined: Thu Sep 06, 2007 9:23 pm

Re: Bad coil?

Post by davidvn » Sun Jul 28, 2019 12:23 am

A spark coil Ceases to work properly when it gets warm because of something known as the Curie effect.
A spark coil is a transformer basically. It has a primary side which is a coil of wire and a secondary side which is also a coil of wire. The secondary side has many more turns of wire than the primary so the voltage can be stepped up from battery voltage to approximately 25,000 V. The primary and secondary are coupled together buy an iron core. When current passes through the primary it magnetize the core.
When the current ceases in the primary The magnetic field in the iron induces A current in the secondary causing your spark. So you have a change of form of energy in the coil. It goes from electrical to magnetic and back to electrical. Without the magnetic field you would lose an extreme amount of efficiency of coupling the primary to the secondary. If a coil gets hot for whatever reason and there are numerous the iron becomes hot. Simply put the Curie effect makes it harder or impossible to magnetize iron at higher temperatures. So as the temperature of the coil goes up what we’re really concerned about is the temperature of the iron core. If you can’t easily magnetize the iron core you can’t transform the current in the primary to induce a current in the secondary. :idea:

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