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When Nice Boats Go Bad (part 7)

Chuck Buck

Jet Boat Addict
Messages
89
Reaction score
98
Points
97
Location
Lake St Clair
Boat Make
Sugar Sand
Year
2004
Boat Model
Mirage
Boat Length
18
Background - my supervisor, who I send status reports to every week, appreciates me keeping him in the loop regarding my boating adventures. Here’s a collection of my latest reports:

"When Nice Boats Go Bad"
a continuing nonfiction work by Chuck Buck.

Chapter 12: Catching Up.

Since my first season of owning a jet boat, the learning curve flattened out until just recently. I’ll get to that a little later, but just to get caught up, a number of previous improvements and “incidents” have taken place since my last report. My favored home port was just too long, too narrow, and had two tight 90° turns, to comfortably navigate, so I installed Cobra Jet Steering “rudders.” This noticeably improved the low-speed maneuverability, BUT I still put enough scratches in the hull against the dock/seawall/etc. to finally call it quits here. In contrast, I launched my I/O’s here fifteen years and NEVER hit anything! So I decided to go to a DNR facility that directly abuts the lake instead, and this has taken all the drama out of it. I also made some measurements and took the boarding ladder to my local welding shop, where they fixed the step angles in about 10 minutes, and for the mere sum of thirty “doll-hairs.” Hat tip to AvE.

I took the crumb-crunchers skiing and tubing on Pontiac Lake, and that was all fun and games until my grandson, in his first-ever attempt at skiing, held onto the tow rope after falling and played “Superman” underwater. He about filled his lungs and I was scared stiff until he finally stopped coughing. At that time, my son and I both said “hey, let go of the rope when you fall!” Subsequent outings have included more fun and less terror.

I’ve sucked weeds a few times, and been very thankful for the hinged HydroSurge intake grate that allowed me to continue on without going for a swim to clear it. This was particularly important toward the end of my first season when I had to do the “salad-shooter” routine and gas it every 100 yards just to get out/in from the weed-choked harbor (another big reason to change launches). I learned a related lesson next spring when I lost my favorite hat overboard; as I circled around to retrieve it, at the last second a rogue wave took me over the top of it and then it was gone. Well, not completely gone – I saw the bill torn off and floating, then got the sinking feeling the rest was stuck in the impeller. Sure enough, anything much above idle induced a bad vibration. It was early May, so the water was only about 50°. I thought about diving in with mask and snorkel, using my homemade aluminum grate hold-open tool and waterproof floating flashlight to clear the intake, but I was seriously concerned about hypothermia.

Lake-validated in non-emergency conditions. I aughta patent some of my inventions.
Tool.JPG

Only about a half-mile out, I instead limped it in at idle and pulled the rest of the hat out in the driveway, no other harm done. If I ever need to do a similar maneuver again, I’ll know better and cut the engine when I get close enough. Sheesh!

Chapter 13: Nirvana.

Fast-forward to this July 6th when I decided to play hooky. Andrea, the ex-owner of my first boat the Sea Hag and I went to Strawberry Island. It was unbelievably calm and deserted, save a few people lazily floating on tubes and a handful of family boats.

Whoa, dude! Check out this weird wave trough on the panorama setting!
Strawberry.jpg

Taking her advice and staying off the water until after the holiday weekend was THE PERFECT strategy, and we explored cuts of all three channels (North, Middle, and South) never accessible before these record high water levels. We only cleared the bridge at Brown’s on Harsen’s Island with two inches to spare! Little Muskamoot Bay was like bathwater, and no obnoxiously loud go-fast boats either – only family boats. It was pure joy! Even the ride back was smooth – a once in a lifetime ride.

Chapter 14: The Best Laid Plans and All That.

So here it was, two weeks after that trip and I finally get the perfect opportunity to take mom out. For reasons, it’s been six years. She’s never been on this boat, and we’re both really looking forward to it. I ran the engine on the flushing hose just to prime the carbs, but then the alarm sounded. At first, I didn’t know why the alarm would be on after the initial key-on “beep,” then I dawned on me to shut the motor down and investigate further. I called mom and told her the trip was off. She understood, but was bummed just the same. I never heard this alarm come on before except at key-on, so I checked the service manual and it said the low oil/oil pump failure alarm is an intermittent “beep, beep, beep,” but the overheat alarm is a continuous “beep.” OK, news to me, as I never got an owner’s manual.

Chapter 15: Willy Make It? Betty Won’t Redux.

Anyway, I figured I sucked some weeds at the launch on the way in two weeks ago as it was pretty nasty, and did my best to flush the cooling system. I then found a small pile of weeds under the jet and figured that was the issue. I ran it again, and sure enough the alarm came on again. With my hands I could feel the starboard head heating quickly while the port head stayed cool, so I figured right there was the issue. I removed the small hose and fitting at the top of the head, and flushed it with full hose pressure aided by a utility pump.

Hose connection locations.
Vent.JPG

With 100’ of hose and a shut-off valve at the end of it, opening the valve produced a strong “surge” of volume and pressure, so I figured THAT had to flush everything sufficiently. I flushed the port head also and nothing more came out, so I trailered it to the launch and fired it up. Once again, the alarm came on within a few minutes so I shut it down, came home, and covered it for the night.

Chapter 16: NOT the Usual Suspect!

Again, more porcelain library time and shower pondering. Since I couldn’t get any more foreign material to come out, I thought pursuing that angle was a dead-end. The merc manual had little to nothing in the way of cooling system diagnosis; not even a diagram of the cooling flow or the various parts involved. I searched the Jet Boaters forum for tips, but found nothing I thought would be of any help. I was now on my own, and it seemed obvious there was insufficient cooling water to the starboard head. Taking from my automotive experience, I wondered if the exhaust gasses from a blown head gasket were blowing out all the cooling water. I decided to do a compression check on all cylinders, just to rule that out. As I was collecting all the tools and putting them onboard, I noticed the “pee hole” next to the bilge pump outlet looked “funny.” Yes, this boat has a pee hole just like a Yamaha PWC. I’ve never seen water coming out while running on the hose, but I did see it flow once while hanging over the side as I was on plane.

Mystery thru-hull fitting.
Pee hole.JPG

BTW, this part or the function of it isn’t mentioned ANYWHERE in the merc service manual, not even in the installation instructions! Anyway, I found it completely plugged with dried mud! Initially, it puzzled me as to the source of the mud, but then it dawned on me – mud daubers! I’ve seen them around, but didn’t figure they’d take up nest building here. I guess I was wrong! Near as I can figure, this vent has two purposes – it serves as a vacuum break to allow the engine to drain when pulled out of the water, and also bleed air from the engine when put into the water. I took the hose off at the port head and tried to blow through it – nothing! With a pocket screwdriver, I knocked out the mud, then blew compressed air from the engine side to clear the hose completely. AH-HA! I knew I found the culprit, but I wanted to make absolutely sure I did no harm during the repeated [momentary] overheating, so I continued with the compression check. All holes were within spec of 15 psi from each other, so I trailered the boat later that day and found nobody at the launch. I fired it up and let it run a good 10 minutes while feeling both head temps with my hands. I could feel the temp rising, then slightly falling in cycles on both heads evenly, so I was confident I had it licked. I pulled away from the dock slowly, just to be sure I wouldn’t get stuck on the water, then as I cleared the no-wake zone I throttled up and beat it like it owed me money for at least five minutes. No overheat alarm! It was a hairy ride against the wind and foot-plus rollers, so I turned for home, gassed it again just to be sure, then brought it in. I mentioned this incident later to Andrea, and she confirmed the mud dauber activity is peaking right now, so it didn’t surprise her one bit. It certainly taught me a lesson, and later I fabricated a plastic plug for the hole and attached it to the tail of the storage cover strap so I won’t leave it in when I take the boat out. Sure, the mud plug was a very unlikely event, but now I’m prepared just in case the daubers eye this spot again.

One of these days, I’ll finally get mom out. We’ve waited this long, we can wait another few days.

Tl;dr – if your Sport Jet is overheating, check your pee hole!

The End (for now).
 
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