Freak fluke all 8 spark plugs burn out at same time !!!?

[DarrinT]

Marina mechanic looks at me with blank look when I tell him all 8 of my plugs burned out at same time!

Did I get hit by lightning?

How could this be possible on a 1980 marinized Chev 350 ?

Yup it ain’t a Mercruiser but a Chris craft 350 in a twin engine Catalina 35 footer but I trust this forum mostly cause for longest time followed advice here for my 71 mercruiser 140 I owned for 10 years changing out the engine , doing own tunes etc.

Total mystery

 

[dubs283]

This sounds more like a no spark situation rather than a spark plug issue

It would be incredibly rare for every spark plug to fail simultaneously

What type of ignition system is currently in place?

 

[Scott Danforth]

My guess is the points need service

 

[Bondo]

Marina mechanic looks at me with blank look when I tell him all 8 of my plugs burned out at same time!

Did I get hit by lightning?

How could this be possible on a 1980 marinized Chev 350 ?

Yup it ain’t a Mercruiser but a Chris craft 350 in a twin engine Catalina 35 footer but I trust this forum mostly cause for longest time followed advice here for my 71 mercruiser 140 I owned for 10 years changing out the engine , doing own tunes etc.

Total mystery

Ayuh,..... Whatda mean, Burnt out,..??

If you're sayin' the electrodes are all burnt off, I'd guess detonation, from bad timing, and/ or a lean condition,.....

If there're just not firin', the ignition system is down,....

 

[stresspoint]

I'm in for a look to see where this goes !.

nothing to add at this point.

 

[DarrinT]

Ayuh,..... Whatda mean, Burnt out,..??

If you're sayin' the electrodes are all burnt off, I'd guess detonation, from bad timing, and/ or a lean condition,.....

If there're just not firin', the ignition system is down,....

Full story
Could not get starboard engine to fire , not even a cough , after running fine 2-3 weeks before
Checked fuel , checked water separating fuel filter , checked spark it’s there but after diddling around for an hour getting mighty frustrated realized the spark plug I’m holding against block is only sparking from the body of the plug at male socket not across the gap
WTF?
Pull a plug from port good engine which is firing up running smooth and stick it in starboard bad engine boom coughs
All of the plugs are bad all at once? Not possible!
Zoom off to automotive store with a plug to match , get a set , run back , install them , Zoom Kaboom fires right up!

In my amateur wisdom I’m thinking that something somehow ruined whatever runs down the Center of every plug!

I am thoroughly befuddled on this one

Sorry boat is winterized in Marina shed on Georgian Bay 2.5 hrs from where I live so no specifics on plug make - this happened last Sept.
Only thinking about it now cause I might sell her this spring

 

[racerone]

There are some very good shops on Georgian Bay.------Anywhere near Parry Sound?

 

[dubs283]

Full story........I am thoroughly befuddled on this one

Still not the full story but getting there

You haven't mentioned what type of ignition system

Your test for spark is rudimentary at best. A spark gap tester is the best as it shows the health of the spark from the system as a whole

I believe your issue hasn't been fully resolved with a new set of plugs and lies within the ignition system prior to the plugs. Spark plugs having good spark being the end result of a sound ignition system it seems you have weak spark.

If you post the style/make/model of the ignition system it will help determine the best course of action to prevent premature failure. The only recommendation I can provide is to perform a full tune up

 

[DarrinT]

Thanks guys
When I’m putting her in the water , likely May 24 long weekend or thereabouts I’ll get hold of a spark tester and get specifics on ignition system and repost then.

 

[DarrinT]

There are some very good shops on Georgian Bay.------Anywhere near Parry Sound?

Just South of Parry Sound on Twelve Mile Bay at Moose Deer Point Marina

 

[stresspoint]

the reason i said i was sitting back on this is, i had a similar situation many many years ago on a ford Cosworth motor ,the same thing happening , IE: sat overnight and would not fire the next day
i still to this day not know what happened to those plugs.
speculation was by some older guys that i spoke to was somehow a voltage spike broke/killed the resistors in all the plugs,? cold and sudden heat maybe
how this could happen still has me bewildered and this is the first time since i have heard of it.

as Op has posted sticking new plugs solved my issue as well.

i never had the issue again and i owned that car for many years afterward

 

[Chris1956]

Is there any foreign substance on the white porcelain of the spark plug? Maybe some kind of oil or saltwater? It sounds like the spark is travelling down the porcelain to the shell and then to the block. Wipe 'em off with some solvent and then fresh water and retry.

 

[dingbat]

Had this scenario happen in a truck one time.

Installed new plugs and "snugged" them up as I had hundreds of times before. Truck wouldn't start.

Called a friend who is a GM Master Tech who told me to get new plugs and use a torque wrench this time.

Finger tight, then snug 1/4 turn to seat. Anymore and you risk damaging the insulator