Tweet
I got the gearshift fixed on my DF25 and a test run on the river showed all to be well. With the new TinyTach installed, the 10x14 prop gave me 25.7 mph at 4600 rpm. The somewhat beat up 10x13 gave me 25.4 mph at 4900 rpm and an easy cruise of 22 mph @ 4200.
Biiig problem now - I took it for a run in the ocean a week ago and ran 9 miles in a big loop to an area I wanted to fish. It ran beautifully. Finished up and started home and at about ~7 miles (16 total miles) the motor suddenly slowed. Ran for a bit and it slowed more, then noticed that the red light on the motor (tiller motor) was on. That's a tiny light and hard to see in daylight and no buzzer.
Long story shorter, I rowed for a while, then another boat towed me the rest of the way to the launch ramp. Nice of him.
When I got home, I put the muff on it and tried to start it. After a long while, with starter really straining to turn it, it finally started and was missing badly. With housing off, I could see jets of mist spurting out of left cylinder head. Left power pack is melted down into intake manifold.
0cyl.jpg
I pulled the cylinder head and found this. The liner is OK and motor turns without binding but the cylinder wall casting is melted away - not broken. It would appear that a very localized hotspot occurred, but I'm not sure why.
When I pulled the valve cover, milky oil poured out - about 1/2 cup. No surprise.
I pulled the lower unit to check the impeller and 2 of the 6 vanes were missing about 1/8" off the tips. A 3rd tip is hanging on by a thread. The motor has Not been started without water and the impeller only has a very few hours on it. I thought maybe the pieces had gotten into the motor and caused a localized restriction/hotspot, so I pulled the thermostat cover. There was no t'stat in there.
From what I can see, the water passages seem very small and the 90º turn the water makes at the top of the tube to get to t'stat makes it seem like it's unlikely the impeller pieces made it that far. Not sure how I'll go about it yet, but I'd tend to think they're still in the water pump outlet tube, upstream of the t'stat. There are some deposits inside the motor's water jacketing, but I doubt they're heavy enuf to cause much restriction. In any case, when (if) back together, it'll get an acid wash.
A local welding shop says he can weld it up nicely, then just have to have it machined true for the head gasket. OK, it'll cost a few $100, but my big concern is future prevention. Is this common with these motors ?? How do I avoid future occurrences ?? The thing ran beautifully for ~16 miles, then blew.
The motor is very stiff to turn over and the starter strains with a fully charged battery. With the lower unit off, the driveshaft is very difficult to turn by hand. 2 other motors I have that I put new impellers in turn quite easily. When I loosen the impeller housing cover, the shaft turns much more easily - about what I'd expect with the seals on the shaft.
I don't think I was lugging the motor - it felt and sounded fine at 4000 - 4200 rpm. I dunno.....grabbing at straws. Any thoughts ??
I'm a very unhappy boater at this point.
Biiig problem now - I took it for a run in the ocean a week ago and ran 9 miles in a big loop to an area I wanted to fish. It ran beautifully. Finished up and started home and at about ~7 miles (16 total miles) the motor suddenly slowed. Ran for a bit and it slowed more, then noticed that the red light on the motor (tiller motor) was on. That's a tiny light and hard to see in daylight and no buzzer.
Long story shorter, I rowed for a while, then another boat towed me the rest of the way to the launch ramp. Nice of him.
When I got home, I put the muff on it and tried to start it. After a long while, with starter really straining to turn it, it finally started and was missing badly. With housing off, I could see jets of mist spurting out of left cylinder head. Left power pack is melted down into intake manifold.
0cyl.jpg
I pulled the cylinder head and found this. The liner is OK and motor turns without binding but the cylinder wall casting is melted away - not broken. It would appear that a very localized hotspot occurred, but I'm not sure why.
When I pulled the valve cover, milky oil poured out - about 1/2 cup. No surprise.
I pulled the lower unit to check the impeller and 2 of the 6 vanes were missing about 1/8" off the tips. A 3rd tip is hanging on by a thread. The motor has Not been started without water and the impeller only has a very few hours on it. I thought maybe the pieces had gotten into the motor and caused a localized restriction/hotspot, so I pulled the thermostat cover. There was no t'stat in there.
From what I can see, the water passages seem very small and the 90º turn the water makes at the top of the tube to get to t'stat makes it seem like it's unlikely the impeller pieces made it that far. Not sure how I'll go about it yet, but I'd tend to think they're still in the water pump outlet tube, upstream of the t'stat. There are some deposits inside the motor's water jacketing, but I doubt they're heavy enuf to cause much restriction. In any case, when (if) back together, it'll get an acid wash.
A local welding shop says he can weld it up nicely, then just have to have it machined true for the head gasket. OK, it'll cost a few $100, but my big concern is future prevention. Is this common with these motors ?? How do I avoid future occurrences ?? The thing ran beautifully for ~16 miles, then blew.
The motor is very stiff to turn over and the starter strains with a fully charged battery. With the lower unit off, the driveshaft is very difficult to turn by hand. 2 other motors I have that I put new impellers in turn quite easily. When I loosen the impeller housing cover, the shaft turns much more easily - about what I'd expect with the seals on the shaft.
I don't think I was lugging the motor - it felt and sounded fine at 4000 - 4200 rpm. I dunno.....grabbing at straws. Any thoughts ??
I'm a very unhappy boater at this point.