The Seagull Part II: Taking it Apart

A few months after last year’s final 4-H fair I got to work on restoring the Seagull. I began at the beginning: taking it apart. There was a lot of rust, dirt, and the gearbox behind the propeller was full of an ominous looking sludge. I looked like a drop of seawater had gotten in at some point, it’s a good thing there was oil in there or the corrosive salt water would have rusted the gears.

Above: The gear box after I drained most of the sludge.

After dismantling the gearbox, I removed the flywheel. The flywheel was stuck tight and it took a lot of hammering (and patience!) to get it out. I spend a five hours hammering, tapping, prying and levering on it, and eventually it gave way. Why the hammer? On small motors the flywheel is bolted onto the crankshaft, which is usually tapered. Hammering gently on the flywheel while a helper pulls up will loosen it from the tapered end.

Above: A hammer is a useful for removing flywheels. Don’t get rough!

Above: One end of the crankshaft. Note the taper.

Many of the bolts were stuck and rusted which made it difficult to take them out. When this problem comes up, be very careful. The last thing you want to do is break a bolt. On British Seagulls the bolts are all Whitworth sizes – somewhere in between metric and imperial – but not quite a perfect fit on either of these sizes. Whitworth wrenches aren’t something you can find at your local Canadian Tire store and buying replacement bolts is difficult too; regular hardware stores don’t carry anything that fits. It’s best to go to a specialist.

Now I had an awkward combination of problems: jammed bolts and tools the wrong size. Eventually, by combing through my grandfather’s tool room I found a bit which fit quite well onto the desired bolt. I carefully loosened the bolt by slowly pushing the rachet back and forth. This can break the corrosion holding a bolt in. I levered the ratchet back and forth, gently, loosening all the rust and dirt around the head of the bolt. Whether it takes one minute or one hour, take your time with this process. You don’t want to break anything!

British Seagulls are water cooled: Water from the ocean is drawn in and forced up a pipe by an impeller to the block, where it fills a chamber that encircles the piston. On my Seagull this water chamber was heavily clogged with rust and it was obvious no water was going anywhere. In the photo below the engine head is removed to reveal the four inlets from which you can access the water chamber. This is handy because through these inlets you can see and clean inside the water chamber. The rusty material blocking these inlets is the rust.

Above: The block, note the water chamber inlets. There are four inlets, one on each side.

Above: The inlets to the water chamber – much more visible after sandblasting.

Above: The crankcase. It splits in half, making it easier to take the cams and piston out.

Next, I’ll talk about the fun part: Sandblasting!

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