1978 6hp Johnson Seahorse

Not So Big Johnson

As luck would have it, SV Belle came with an outboard motor. A little undersize to my liking given the 15hp rating on the boat, Not So Big Johnson is a 6hp 1978 Johnson Seahorse long-shaft.

Since Belle had not been registered in some 27 years, we assumed Not So Big Johnson (N.B.J.) had not run in that long either. After the disappointing outing with Grumpy Von Crankenstein, I set to giving N.B.J. a much-needed tuneup.

Since water pump impellers are an annual maintenance item, I ordered a water pump repair kit sight-unseen as well as a carburetor tune-up kit and new sparkplugs. The water pump proved to be a hassle. There are four screws that hold the pump housing down, and also keep seawater out of the lower unit by clamping a gasketed cover under the water pump (bad design IMHO). Three of these flat head screws came out with much tapping of an impact driver. The last snapped off. I had to drill out the #10 screw from the casting and tap a new 1/4-20 screw thread as well as drill out clearance in the plates and housing.

The impeller was surprisingly supple but I replaced it just the same as well as the oil seal that the drive shaft passes through into the lower unit (again, keeping seawater out is a good thing). I reassembled the motor and decided to giver’ a go before tearing down the carburetor.

We took the engine to the family lake house and once again used the old johnboat as the test vehicle. This time, we were power limited as the plywood transom reinforcement has since rotted out badly. A slight twist of the throttle produced a significant twist in the transom. We seemed to be in luck and the engine started right up. Puttering around the cove, it soon overheated. No significant water was peeing out the “indicator” either. My brother and I pulled the pump apart a few times and proved it worked by spinning the shaft while holding the lower unit in the lake. Water would squirt out the pump if I spun the shaft fast enough. So, we set to trying to un-plug the engine block. We pushed some wire up the drop tube and blew air from a tiny compressor unto the indicator and exhaust to no avail.

Finally, with Not So Big Johnson on the johnboat, I put it in neutral and gave it a good twist of the throttle. Whatever was in the engine must have broken free and water started peeing out from the indicator. Success!

Follow the adventures of Belle and Not So Big Johnson!