Visible Sparks at Coil

[jimsnyder1]

1997 Bayliner Ciera 2355, 5.7 Mercruiser left me set and had to be towed in. Looked at coil and saw visible sparking while cranking but wouldnt start. This boat had been running just great. Assumed it was coil or wire so replaced both and now still have sparking and wont start. Any Help would be appreciated.

 

[HT32BSX115]

Re: Visible Sparks at Coil

That should be a Thunderbird V ignition system.

If you have sparking at the coil it could be a high resistance connection at the dist.

Sometimes high energy ignition systems will "find" a path to ground if they cannot "spark" thru a sparkplug..... Have you had a look under the cap?

Also have a close look at where the (new) coil wire goes into the cap. If it was poorly or not connected to the distributor cap you might get arcing at the coil. either internally or externally.

Also, if you handled the coil with wet hands (sweat , salt or brackish water) you may be providing a path for current to flow.


Cheers,


Rick

 

[jimsnyder1]

Re: Visible Sparks at Coil

Thanks Rick, will try each one of these and will give feedback. I did have a incident last week where the sparkplug separated and blew out of the hole, thought maybe this had something to do with it.

Jim

 

[bruceb58]

Re: Visible Sparks at Coil

Check all your spark plug gaps. If they are too wide, this will also cause this. Are all your wires in good condition? Cap? Check your coil and look for any cracks.

Basically, the spark has to go somewhere. If the path to the sparkplug and and across the gap isn't a good one, you will get arcing....somewhere.

 

[fossill]

Re: Visible Sparks at Coil

You should never have spark arcing at the coil or anywhere for that matter, unless you have a defective coil and or wire assembly. Make sure that wire is fully seated in the coil. Also make sure you got clean hands when you assemble. You get the connection end dirty with carbon you get yourself a path for spark to arc on. Also, coat both ends with silicon dielectric grease, along with the plug wires on both ends.
I'd also replace the plug wires along with cap and rotor if everything is original. Plugs while I'm at it too. Every 5 years/60,000km was the rule of thumb when I worked in the auto repair industry regardless of mileage.

 

[gadget73]

Re: Visible Sparks at Coil

oh no. You actually had a plug insulator blow out of the plug socket? The only time I have ever seen that happen was on a boat with a popped head gasket from being severely overheated. The plug was replaced, and the engine sucked a load of water, causing a hydrolock at 3500 rpm, destroying the engine. Be really really sure why that plug came apart or you might be looking at extremely extensive repairs.