Are these Coils still good?

[rpaldrich]

1987 Mercruiser 260 Thunderbolt IV ignition system, Alpha One drives. Wellcraft II Spyder

I just bought this boat and am working on getting it ready for the season. The boat sat unused and covered for the past 3 years. The STBD coil had some electrical tape covering the connections, with some black marks. The coil spark wire feels like it is making a good connection, the rubber boot around the coil spark wire is not the tightest around the coil. Could this cause arcing? Do I need coil wire or new coil?

The PORT coil spark wire was broken, and caused some arcing inside the coil's female side, the coil also has some cracking. I need a new wire, but how about the coil? Is it still ok?

Also, this looks like a vacuum advance port on the distributor?-but neither engine has it going to anything. Is it just a drain?

 

[Don S]

Re: Are these Coils still good?

Cracked coil towers, jumping spark, corroded terminals, all indicate a bad coil. Usually because the distributor cap, spark plug wires or spark plugs failed.
If the cap, wires, or plugs don't fire, that 25-50K volts supplied from the coil to the spark plugs to fire the engine looks for a place to go. Over time, it overloads the insulation cover of the coil and damages the coil.

 

[mjdh_80]

Re: Are these Coils still good?

Is it necessary to replace the coil with a marine one, or will an automotive coil be ok?

 

[rpaldrich]

Re: Are these Coils still good?

Cracked coil towers, jumping spark, corroded terminals, all indicate a bad coil. Usually because the distributor cap, spark plug wires or spark plugs failed.
If the cap, wires, or plugs don't fire, that 25-50K volts supplied from the coil to the spark plugs to fire the engine looks for a place to go. Over time, it overloads the insulation cover of the coil and damages the coil.

Thanks Don, if I understand you correctly, the coils are bad, need replacing, and failed bc the plug wires, plugs or distributor is bad. Will the thunderbolt ignition flow diagram referenced on this site show me what's wrong once I replace the coil? Or is it an intermittent problem?

 

[rpaldrich]

Re: Are these Coils still good?

I found the answer to my distributor question... it is a vent:

Still wondering---other than coils, do I need to start replacing wires, distributor parts and plugs?

 

[FishHog]

Re: Are these Coils still good?

well those are all good tuneup/maintenance items so I would. Whether you "need" to can only be determined by you and testing each item. Not that expensive to just replace and know they are good.