Re: [omc-boats] Last run of the season

That's an interesting failure mode experience, Ethan. I used to have a
poster that showed various spark plug failures and reasons, but darned if I
know what happened to it. I did find a nice link at Champion (see below),
but there's nothing that looks related to what you experienced. (Some of
the other brands might have more; I only checked Champion.) You are
probably right that it had some minor damage early on and the stress cracks
built up over time until it finally popped. You're especially lucky nothing
fell into the cylinder and tore it up.

Are you using dry suits to wakeboard in 40F water? If so, how well do they
work? I've tried skiing and sailing (wet sailing) in wet suits, but found
the dry/wet/dry/wet cycles rendered them less effective (vs. just staying
wet) as I was constantly needing to warm fresh water each cycle. I've never
been able to try a dry suit and haven't been willing to put out the pile of
cash they cost for fear they won't work much better or will be too much
hassle to put on. Would be interested to hear your experiences with them,
if you have any. Regardless, I give you much credit for braving that kind
of weather!

http://www.championsparkplugs.com/sparkplug411.asp

Andy Perakes
1967 Reveler 155

----- Original Message -----
From: "Ethan Brodsky" <brodskye@...>
To: <omc-boats@...>
Sent: Thursday, November 30, 2006 11:44 PM
Subject: [omc-boats] Last run of the season

> I haven't posted for a while, but I thought this was something you'd all
> enjoy. I tried posting this yesterday, but for some reason it didn't seem
> to go through (or at least I didn't get a copy back). I apologize if
> anyone sees it twice.
>
> This has been an unusually good year for my boat, a 1970 Evinrude Explorer
> 16' with the 155 hp Buick 225 V-6. Unlike previous years, in which I was
> fixing something on the boat or trailer every other month, the only
service
> I've done this year was to replace the tilt motor at the start of the
> season.
>
> We've had unseasonably warm weather in Wisconsin these last few weeks,
> though I've unfortunately been too busy to enjoy much of it. As air temps
> neared 60 this afternoon (normally it'd be near freezing this time of
> year), I blew off work early and took the boat out with some friends in
> hopes of getting in some late-season wakeboarding.
>
> We were enjoying having the lake entirely to ourselves and were changing
> into our wetsuits as we cruised at half-throttle cruise to a good ski
area.
> We'd made it about halfway when I heard a loud bang from the back. My
> buddy who was driving immediately cut the throttle and shut off the
engine.
> I lifted the engine cover and could see a red-hot spark plug sitting on
top
> of the engine. The spark plug had fractured, with the outer metal section
> remaining threaded into the head and the center ceramic core blowing out.
>
> I had some spare spark plugs in the glove box, but I'd unfortunately put
my
> tools into the car before setting off (though now that I think of it, I'm
> fairly sure there is a rusty old spark-plug wrench that's lived in the
boat
> since I bought it and fell into a gap between the side locker and the hull
> earlier this year).
>
> As we were the only people on the lake, it was nearing dark (we'd only
> planned on wakeboarding for 45 minutes), and all my friends have already
> put their boats away for the season, our only options were to call the
> sheriff or attempt to make it the 2.5 miles back home ourselves.
>
> We tried starting the engine. Aside from the sound of air rushing in and
> out through the empty spark plug hole, there were no other bad sounds and
> it idled smoothly. It seemed possible that running it on five cylinders
> this way might not cause any additional damage to the engine, though I was
> concerned about excess fuel in the dead cylinder washing oil off the
> cylinder walls and wrecking the rings. I also probably should've been
> worried about chunks of the plug damaging the valves, but didn't think of
> it at the time. I called a couple mechanic friends on my cell phone and
> they told me running like that shouldn't cause any additional damage.
>
> It took about an hour to get back across the lake at idle. The popping
> sound from the engine made it sound like a steam engine, and I could see
> gasoline mist jetting out of the hole with every pop. With the hood open
> it didn't seem to accumulate too much, but I stood by with the fire
> extinguisher in case it did. We thought about heading in another
direction
> to a nearer pier (about 1.5 miles away), but it seemed to be running ok
> so we went back to the spot we launched.
>
> [added later] I pulled the remnants of the plug a couple days later. It
> came out fairly easily and the outer electrode was fortunately intact. I
> didn't have the tools to look inside the cylinder to inspect for damage
> to the valves or piston top.
>
> I put up a photo of the inner and outer part of the broken plug here:
> http://homepages.cae.wisc.edu/~brodskye/boat/blown_sparkplug.jpg
> (alongside a rusty one I took from my glove box)
>
> Any ideas why this might have happened? Water temp was about 40 F, air
> temp was about 60 F. Obviously there's more potential for thermal shock
> with such cold water, but we'd run it it already without trouble (though
> only for a few minutes). I'd run once since topping off the tank with new
> fuel a few weeks ago, but dumped stabil in a few days before this run. The
> plugs are 2-3 years old (installed by the previous owner). It was the
> middle cylinder in the starboard bank. If you look carefully at the break
> surface, it appears to be half black and half clean, which says to me that
> the failure took some time. I'd say the plug must've been mechanically
> damaged or stressed in the past, but it's pretty well protected between
the
> valve cover and exhaust manifold. Perhaps I might've hit the wire while
> installing the battery and side-loaded it, but I doubt that. The engine
> was running fine for about 10-15 minutes before it blew, though I did hear
> a some unusual pops (maybe 5-10 total) during that time. I did notice the
> exahsut manifolds felt unusually hot right after it blew, but not
> excessively so (I could still put my hand on them). I verified that there
> was still water going through the engine and it ran cool at idle on the
way
> home. So I'm very puzzled as to the reason. My best guess is that it was
> dropped prior to installation. Needless to say I will be replacing all
the
> other plugs as well.
>
> I've got a few other projects planned for this winter. I'm going to '
> replace the crank on the trailer winch (it's rounded off and slips),
> probably with some kind of hex-head or square-drive contraption that I can
> use a wrench on if necessary. I'm also hope to get the fenders put back
on
> the trailer and repair/replace the lights so it's legal again.
>
> On the boat, I want to repair or replace the oil/overtemp light in the
dash
> (wires fell off the bulb housing). I also want to mount my bottom-finder
> transducer in the bottom of the bilge, since it broke off its old mount on
> the transom. I have a new automatical bilge pump that I'll probably put
in
> in place of my old manual one. I need to replace both back seats and I'd
> like to also do the front seats, as they're all rotting out. I'd also
like
> to move the electric fuel pump, pressure regulator, and filter above the
> top of the tank so that I'm legal. Finally, I want to repair the panels
> under the back seat that seal off the engine compartment.
>
> I'm not sure how much of this will get done, but those are my goals. A
lot
> of it depends on the weather, as I have to work on it outside.
>
> Anyway, it's supposed to get down to 15 degF by Thursday, so I'm probably
> not going to get another chance to go wakeboarding this season. To anyone
> in a warmer locale, please take a run for me!
>
> Best wishes,
>
> Ethan Brodsky
>
>
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Received on Friday, 1 December 2006