A word about changing spark plugs in your outboard....

[fishinwrench]

Nearly every outboard that comes in to my shop has brand new spark plugs, mostly because that's what many folks do when their motor starts acting up. 

Truth be told: The spark plugs are the last thing subject to be causing running problems.....but folks know how to change spark plugs (or at least they THINK they do) so that's where outboard diagnostics always tends to start at home. 🙄

Issues arise when people go to the Auto parts store, walk up to the counter and say "I need spark plugs for a John/Rude 150" and the person behind the counter pulls up their page of info containing everything they think they need to know about spark plugs.....and then cross-references it to WHATEVER THEY HAVE IN STOCK.   

This is the result of running NGK crossovers in an Evinrude 150 Intruder.  

The correct plug is a Champion QL77V for a reason. 

The NGK crossover does not have the proper heat range.....So the kid behind the counter at O'Reilly's, or whoever trained him, should have to buy this powerhead !    

[aarchdale@coresleep.com]

Glen, quit giving people logic let, them F up and fix it for them.   I always bite the bullet every year and buy the expensive plugs for mine. I mix my oil so i figure $65 a year is worth it 

[fishinwrench]

Yet again......It appears to be an ongoing epidemic.

Catastrophic detonation/pre-ignition. Uncommon on a lower cylinder (the coolest running cylinder of them all).....but nevertheless.

[tjm]

Can you rebuild that, or is gone?

[MrGiggles]

On 7/19/2023 at 6:47 PM, fishinwrench said:

Nearly every outboard that comes in to my shop has brand new spark plugs, mostly because that's what many folks do when their motor starts acting up. 

Truth be told: The spark plugs are the last thing subject to be causing running problems.....but folks know how to change spark plugs (or at least they THINK they do) so that's where outboard diagnostics always tends to start at home. 🙄

Issues arise when people go to the Auto parts store, walk up to the counter and say "I need spark plugs for a John/Rude 150" and the person behind the counter pulls up their page of info containing everything they think they need to know about spark plugs.....and then cross-references it to WHATEVER THEY HAVE IN STOCK.   

This is the result of running NGK crossovers in an Evinrude 150 Intruder.  

The correct plug is a Champion QL77V for a reason. 

The NGK crossover does not have the proper heat range.....So the kid behind the counter at O'Reilly's, or whoever trained him, should have to buy this powerhead !    

Sounds more like NGK should be footing the bill if they are listing their plugs as compatible.

What plugs did you take out of them?

[fishinwrench]

13 hours ago, tjm said:

Can you rebuild that, or is gone?

It can be rebuilt as long as it doesn't throw a connecting rod through the block.   

Either the damaged cylinder(s) will cleanup at .030 or they will be sleeved.   

[fishinwrench]

4 minutes ago, MrGiggles said:

Sounds more like NGK should be footing the bill if they are listing their plugs as compatible. I know the heat ranges are backwards (bigger number is cooler on NGK, opposite for Champion) but I always thought the numbers in the middle (7/8) were comparable.

They will just lay the blame on the EPA. 

Back in the day when it was ok for outboards to smoke a little bit, a hotter plug reduced fouling...... but now that engines are designed to run as lean as possible, in order to reduce emissions, a plug that runs hotter than it needs to is a bad thing.   

They'll recognize and rectify the issue eventually, but more powerheads will be sacrificed along the way.   My heads-up here was intended to keep YOURS from being one of them. 👍 (cuz I'm a cool guy like that) 😁

[tjm]

That's what I thought, on the rebuild, but I have zero experience or knowledge of boat engines.  Don't people ever look at and test the old plugs before just tossing them?

[MrGiggles]

6 hours ago, fishinwrench said:

They will just lay the blame on the EPA. 

Back in the day when it was ok for outboards to smoke a little bit, a hotter plug reduced fouling...... but now that engines are designed to run as lean as possible, in order to reduce emissions, a plug that runs hotter than it needs to is a bad thing.   

They'll recognize and rectify the issue eventually, but more powerheads will be sacrificed along the way.   My heads-up here was intended to keep YOURS from being one of them. 👍 (cuz I'm a cool guy like that) 😁

My powerhead will blow again before I every need to worry about spark plugs. 

[fishinwrench]

5 hours ago, MrGiggles said:

My powerhead will blow again before I every need to worry about spark plugs. 

Ahh, running a Mercury are ya?    

Then yep, you're probably right. 😅    Most Mercs don't outlast their original set of spark plugs