Re: Reviving a LT-39

[kevinf]

Hi Karl

I have a few Johnson’s with that type lower units (LT, LS ans HS) but I’m no expert by any stretch. As David pointed out there’s no impeller – it’s a small piston pump riding on an eccentric. Check for wear through in the contact areas. I heard on these forums that a common fix was to solder a penny over the face. Make sure that the small ball bearings in the check valve are in place and free to move.
There is a coil spring in the drive train between the gear set and the prop. It serves as a shock absorber. Check the point where the spring mounts. I have a couple where that has broken/worn through.

At the other end of the motor the ignition is a bit special. It’s got a single coil like an opposed twin and a single contact point. There are grounding brushes on the coil and an insulator under the flywheel that are used to make the coil fire alternate cylinders. Check the resistance across the plug wires rather than plug wire to ground and make sure everything is clean. Make sure as well that the ground points in the insulator under the flywheel are clean and grounding.

There’s nothing tricky in those motors and they run well they’re just a wee bit different.

Other members feel free to jump in and correct me if I’m wrong 🙂

Kev