Spark Plug Maintenance

[TurboDan]

The last time my car was in for a repair, the mechanic said that he changed the spark plugs because they were very dirty and crusty with whatever spark plugs get dirty and crusty with.   

Anyway, my boat has been out of the water for the past week, waiting for me to do the unglamorous task of scraping off barnacles.  After I applied the barnacle-disintegrating chemicals which nearly killed me, I got the barnies off and decided to perform a little maintenance on the engine.  Changed the anticorrosion solenoid and a couple other little things and refitted the hood so it won't vibrate anymore!  Then, I decided to take a look at the spark plugs.  They've been in there for about four years, never having been changed and cleaned probably only once.  This is a carbureted outboard engine (meaning that you fill the tank with a pre-mix 50:1 gas-oil) so things can get sloppy if you put a little too much oil in.  The engine has been performing very well, but I noticed that the plugs were pretty much black.  I took out a wirebrush and got alot of the black off, though they are still stained and the "inside" portion of the plug that I can see looks pretty messy.  Is it OK just to go over plugs with a wire brush, or would you suggest just buying new ones?  Like I said, the engine runs OK, but the plugs didn't look exceptional.

What's the proper way to get gunk off of your spark plugs, anyway? 

Also, I have absolutely no clue what the gap is on these things.  If I brought the old ones into a parts store, would they be able to get the gap width and gap the new ones the same?  If not, I'll have to go digging through my stuff for the engine manual.

Thanks!

[280Z Turbo]

I guess that would work. The gap should still be correct.

You just need a feeler gauge to gap them. It's really easy.

Spark plugs are usually super cheap. Just replace them. I used to change them every couple of weeks before I overhauled the engine management system on the Z.

I'm sure the plugs are quite black. That happens when you burn oil!

[SaltyDog]

I've never heard of cleaning spark plugs because they are so cheap. 

I use a marine spark plug(maybe that's similar to what you would need) for my lawnmower and it only costs a few bucks.  Maybe that's similar to what your boat takes, but I know squat about boat engines.

[280Z Turbo]

Cleaning spark plugs usually doesn't do any good, in my experience.

[S204STi]

I know Nissan recommends just replacing them, apparently it isn't worth the bother on our cars to try cleaning them.

[SaltyDog]

New plugs is of the easiest/cheapest ways for better fuel mileage too.

[MX793]

We had a device for cleaning spark plugs at the shop I used to work at.  It was basically a small sand blaster that you plugged the plug into and it would blast the crap off the electrode.  Hardly got used because plugs are so cheap that you might as well buy new ones.

[Danish]

We had a device for cleaning spark plugs at the shop I used to work at.  It was basically a small sand blaster that you plugged the plug into and it would blast the crap off the electrode.  Hardly got used because plugs are so cheap that you might as well buy new ones.

I think I used one of things in HS auto shop....

[TurboDan]

Looks like I'll be going plug shopping tomorrow.  I really have no clue what the gap is, though.  If I brought my current plugs in, would they be able to match them up at the auto parts place?

[Rupert]

I think so. It doesn't say in the manual or somewhere online, eh? They might have it somewhere on their computers in the car shop, but in my experience, those computers aren't always full of reliable information.

[MX793]

I think so. It doesn't say in the manual or somewhere online, eh? They might have it somewhere on their computers in the car shop, but in my experience, those computers aren't always full of reliable information.

But these are sparkplugs for a boat motor, not a car.

[TurboDan]

I think so. It doesn't say in the manual or somewhere online, eh? They might have it somewhere on their computers in the car shop, but in my experience, those computers aren't always full of reliable information.

If I could find the manual, I'm sure it'd be in there. 

I doubt the computer at an AutoZone would have boat engines in there.  I could ways go to a marine store and check it out.  Then laugh when they tell me it'll be $30 for a spark plug. 

[MX793]

If I could find the manual, I'm sure it'd be in there. 

I doubt the computer at an AutoZone would have boat engines in there.  I could ways go to a marine store and check it out.  Then laugh when they tell me it'll be $30 for a spark plug. 

Do you know the make and model of the motor?

[giant_mtb]

Here's a trick I learned to make spark plugs work like new...

Use a blow torch.  Light up the torch and scorch the plug until it's literally red hot...and there ya go.  All those deposits and gunk are gone.

[sparkplug]

I think you will be able to find them at Autozone or especially at NAPA. You'll need the year, make, hp, and model # of your boat engine. Tell us if it fixes the problem.

[Rupert]

Oh, yeah, I forgot it was a boat engine we were talking about...

[TurboDan]

Stopping NAPA in the morning.  I'll let everyone know how it turned out.

[TurboDan]

Got the plugs, bought a gapper, all is right with the world.

[J86]

Just ouf of curiosity, what is your boat powered by?

[TurboDan]

Just ouf of curiosity, what is your boat powered by?

90HP Johnson

[The Bartender]

As already noted, there is mini sand blaster tool that can clean plugs.  The shop I used to work for had one, but we just used in once in a while to clean flooded plugs.  (This was in 1986, so flodding was still a problem.)  You wouldn't throw out brand new plugs because they were flooded.

But other than that, yeah, it's so chep to replace plugs, you might as well.  Plus, over time, the insulators break down.  You can sometimes see hairline cracks in older spark plug insulators if you look real close with a magnifying glass.  The cracks create another path for the spark to follow, causing misfires.  S go ahead and replace them.  I would think that the gap data should be available froma marine engine store, or you could check to library for repair manuals on your motor.

[J86]

More motor!!!